| 00:03 | All right, y'all, let's go and get started. Um For those |
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| 00:06 | you who registered uh after the first , uh this is kind of the |
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| 00:10 | information you guys um you missed out a lot of fun on Tuesday. |
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| 00:16 | know, you know how long that incident lasted. It was including me |
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| 00:21 | back down was about six minutes, less, maybe about five minutes, |
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| 00:26 | is crazy because it felt like 30 to me anyway. So uh uh |
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| 00:32 | far as orientation is concerned, uh a link directly on the front page |
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| 00:36 | Black or not Black, excuse me campus, you can click that. |
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| 00:38 | take you to all our recorded You can go and watch that for |
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| 00:41 | orientation. I edited out the bad um today. If you saw it |
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| 00:47 | then. Yeah. Um There's an uh assessment that you should do that |
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| 00:53 | be done uh by Friday uh September by midnight. It's really quick. |
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| 00:58 | just basically summarize everything we discussed uh Tuesday. Uh We have reading assignments |
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| 01:04 | day. What do you guys think the first one? Was it hell |
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| 01:06 | was it. Ok. It was right there. Like I said, |
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| 01:11 | gonna be like, one or two are really, really dense. They're |
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| 01:13 | be coming up here real soon. we get past that, the stuff |
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| 01:16 | gets pretty interesting. But like I , also, this is like, |
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| 01:21 | to the gym for the very first . It's like, you've never worked |
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| 01:24 | like this and so it's gonna be little painful to start off. Every |
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| 01:28 | is like, this sucks. You about midway through. It's like, |
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| 01:30 | , no, there's no big So, um anyway, so there |
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| 01:34 | reading assignments. So we call this two. So lecture three is on |
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| 01:39 | . So make sure you start doing . I call them quizzes here from |
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| 01:43 | old slide, but they're just Did you read this stuff? They're |
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| 01:46 | straightforward. What do you think was assessment hard at all? Yeah. |
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| 01:51 | . And in the grand scheme of , uh, if something is |
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| 01:54 | like if you know, if if you miss a question, it |
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| 01:58 | isn't gonna cause you a lot of . It's if you miss many, |
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| 02:02 | quizzes where it actually starts affecting your . So if you have questions, |
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| 02:06 | can email me. Um I've discovered if you try to email me through |
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| 02:11 | , it, it gets, I the email but I can't email you |
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| 02:14 | for some strange reason. I I get, it gets bounced |
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| 02:18 | So just to give you a heads . So email me directly is probably |
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| 02:21 | easiest way to do so c way U dot edu. All right. |
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| 02:26 | we're actually doing today, we're finally start talking some physiology. Why you're |
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| 02:31 | here? All right. So I to kind of distinguish something here up |
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| 02:35 | the front end, what physiology is what it is not. So, |
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| 02:39 | by definition is the scientific study of functioning, living things. It's how |
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| 02:46 | things work, the systems and the in the bodies, which is structure |
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| 02:51 | really anatomy. But the physiology is do these things actually work to make |
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| 02:57 | organism or the organ or the tissue the things that it does. All |
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| 03:02 | . It's a sub discipline of meaning it covers many, many different |
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| 03:07 | and we're and not often at this , but you'll see that we're gonna |
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| 03:11 | drawing on other disciplines very often. right. Um And so don't be |
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| 03:17 | when there's stuff like, wait a , I've seen this stuff before in |
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| 03:19 | class because everything is kind of integrated you're dealing with this subject matter. |
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| 03:25 | central theme of physiology and what we're talk about first is this question of |
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| 03:31 | , what is homeostasis? You've learned simple definition in biology, one, |
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| 03:35 | you remember this homeostasis is simply maintaining consistent internal environment despite the fact that |
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| 03:42 | change, constantly going on and So when we're looking at these |
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| 03:47 | we're kind of asking the question how does it do this? How |
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| 03:51 | the heart maintain a heartbeat? How the lung determine how much air goes |
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| 03:55 | and out? What is the proper balance of all these different things? |
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| 04:00 | talk about things that sometimes we find uninteresting like osmosis. You guys remember |
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| 04:09 | , right? In fact, we're be talking a lot about that today |
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| 04:12 | over the next couple of days, ? So homeostasis is kind of uh |
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| 04:17 | grounding point of where we kind of that leap off from physiology or for |
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| 04:23 | . Now, who can tell me pathology is just blurt out an |
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| 04:30 | study of disease. So many of are taking this class because that's what |
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| 04:36 | interests you is why do these bad happen, right? And very often |
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| 04:41 | go into a textbook, you especially those that are geared towards undergrads |
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| 04:44 | they know what will make them Are these case studies? Right? |
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| 04:49 | , we're gonna learn about diabetes. gonna learn about cancer, right? |
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| 04:55 | it's like, uh well, you what cancer doesn't mean anything if you |
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| 04:59 | know how the body actually works. so what we do here in this |
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| 05:03 | is we don't do the case studies I apologize for that partially because I've |
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| 05:08 | to do like case studies where I'm to explain something and they're like, |
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| 05:11 | , I don't understand how this is going on. So we have to |
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| 05:14 | kind of ground ourselves first in that before we can make that leap into |
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| 05:19 | pathology, which I know is more . I mean, it's what got |
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| 05:22 | excited about the field in the first too. Right. So you'll notice |
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| 05:27 | I kind of steer away from that . Secondly, I'm not a |
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| 05:31 | And so when, when we start out into the case study stuff, |
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| 05:35 | actually wading out deep into areas I'm comfortable in, right where you start |
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| 05:40 | questions because many of you are doing or have spent time in the hospital |
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| 05:43 | doing stuff like that. And you're , oh, oh, I've seen |
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| 05:46 | . Can you tell me how this ? And I'm like, no, |
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| 05:49 | don't even know what those initials So, you know, it's a |
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| 05:54 | of me not being introduced to the . Now, we can usually kind |
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| 05:57 | critically think our way through some of stuff, but I can't tell you |
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| 06:00 | any sort of certainty how certain disease actually work because I've never looked at |
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| 06:06 | , right? So that's why I of avoid them. But our |
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| 06:10 | like I said is gonna be Now, most of you already know |
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| 06:15 | physiology, most of you know, lot of physiology, just not the |
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| 06:19 | details, details that we're gonna be into. And I want to kind |
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| 06:22 | prove that to you. So I this slide, I've been doing this |
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| 06:25 | a little while. So these are different systems that we're gonna be |
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| 06:29 | Um It's not actually shown up which is good. So the immune |
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| 06:33 | is one that we don't cover in class because it's so grossly complex and |
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| 06:37 | uh time consuming that most texts just we're not even gonna bother. We're |
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| 06:41 | gonna leave that for a completely different and if it interests you, I |
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| 06:45 | encourage an immunology course for you. But it is dense. So here |
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| 06:51 | go. These are the uh different . I wanna just again blurt out |
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| 06:55 | the integument that your skin. What you think it does protects your |
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| 07:00 | That is a good answer. That the textbook answer. But it also |
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| 07:03 | highly, highly metabolic. It plays major role in immune defense. It |
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| 07:08 | all sorts of little tiny things that don't really consider. But protection is |
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| 07:12 | you do, right. I'm gonna another one out here. Uh |
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| 07:15 | What does that do? Breathing? . Yeah. Good. So then |
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| 07:19 | first thing we have to do well, what is breathing? So |
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| 07:21 | moving air in and out, What is air? Is it |
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| 07:30 | Right? It's a, it's a of gasses is what we're looking |
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| 07:34 | right? And that's, that's, right. Your nitrogen is oxygen is |
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| 07:37 | dioxide. Those are the three big . And carbon dioxide of that group |
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| 07:40 | like 0.2%. It is next to . In fact, if you look |
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| 07:45 | most uh air things, it's like , oxygen, other stuff, |
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| 07:50 | But respiration is the process of getting near ourselves, right? So that |
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| 07:57 | can draw the oxygen to our ignoring all the other stuff and then |
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| 08:03 | us to exhale and remove the carbon from our body. So it plays |
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| 08:07 | major role in the process of providing nutrients or the fuel for our bodies |
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| 08:13 | well as getting rid of the waste our bodies. But that's not all |
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| 08:17 | . As an example, it has highly or an incredible metabolic role, |
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| 08:22 | ? Plays a role, immune It's on the surface. So every |
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| 08:26 | you breathe in and all those horrible that enter in your body with every |
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| 08:31 | , guys don't think about this too . Do you? There's all sorts |
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| 08:34 | horrible things out in the air plays role, immune defense. So |
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| 08:42 | there's the big picture and then there's stuff as well. All right. |
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| 08:45 | renal system, kidneys. What does do? Gets rid of waste? |
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| 08:51 | that what she said? I couldn't . Yeah. Yeah. Ok. |
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| 08:54 | system. Yeah. It purifies the . Right? Great. Well, |
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| 08:58 | the key thing. It purifies blood just get rid of waste. It |
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| 09:02 | the blood. It serves as a to take the blood and whatever is |
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| 09:05 | in it and then it parses through in some really cool ways to we're |
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| 09:10 | get to explore. And it says are the things the body wants, |
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| 09:13 | are the things the body doesn't gets rid of the things that the |
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| 09:15 | doesn't want. But it also is for your blood pressure. Well, |
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| 09:21 | , that's one of its major right? Making sure that your |
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| 09:24 | So balances are correct also that a endocrine organ plays a role in regulating |
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| 09:30 | whole bunch of different things, including many red blood cells you produce, |
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| 09:35 | ? So there are things that you know. And so we're gonna look |
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| 09:40 | all the things you know, and those function, but we're also gonna |
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| 09:44 | deeper into the things that you don't , which is kind of cool. |
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| 09:47 | when you start looking at it as whole, it's like, oh, |
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| 09:50 | share a whole lot of things in . And so one of the ways |
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| 09:54 | you approach physiology is you need to of it, not in terms of |
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| 09:58 | are the things I need to But what are the themes that I |
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| 10:01 | seeing? What are the patterns that showing up over and over and over |
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| 10:06 | . And that's kind of what this unit is about is like, we're |
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| 10:09 | to demonstrate a couple of themes that guys should be aware of. So |
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| 10:14 | when we jump from system to You're like, oh, ok. |
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| 10:17 | saw this over here. I'm kind seeing the same thing over here. |
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| 10:20 | just maybe a different molecule that's doing , but it's kind of doing it |
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| 10:24 | the same sort of way. Which makes things easier to learn because |
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| 10:30 | you're dealing with concepts, you just that mold and you just move it |
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| 10:34 | where you need to be. But you spend all your time trying to |
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| 10:37 | stuff, you end up with a vast uh amount of knowledge that may |
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| 10:41 | not be usable ever again, So kind of watch for themes as |
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| 10:46 | going along. And that's like I , first unit is gonna feel like |
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| 10:50 | . It's like when are we gonna to the, the physiology? Trust |
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| 10:53 | , we're gonna be running through some pretty quick. All right. |
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| 10:56 | our starting point has to do with you guys learned in chemistry, always |
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| 11:02 | the chemistry chemists, stick their fingers noses in everyone's business. All |
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| 11:08 | you guys heard of that term law mass balance? All right. Maybe |
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| 11:12 | . Maybe you've heard of the law Mass action. No, you |
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| 11:18 | you just forgot it because it was . All right. And basically what |
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| 11:22 | says is that if you have a , whatever goes in what is, |
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| 11:25 | equal, whatever you put into the has to be the same as what |
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| 11:29 | out or vice versa. Whatever ever out has to be equivalent to what |
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| 11:32 | put into a system, given a or given an open system. All |
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| 11:36 | . And so, for example, say you are, have a plate |
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| 11:40 | front of you and it always has have four cookies on it. Let's |
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| 11:42 | them what? Oreos? Oreo sound today. OK. Double stuff or |
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| 11:49 | weird generation. All right. So got regular Oreos, you got a |
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| 11:53 | of four. You can eat as Oreos as you want. All |
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| 11:56 | But there always has to be four on the plate. Now, you |
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| 11:59 | an infinite pantry over here. So can go and say, I'm gonna |
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| 12:02 | three Oreos if I eat three what do I have to do? |
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| 12:06 | to the pantry, put three Oreos on the plate. All right. |
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| 12:09 | is equilibrium. That is what the balance says, right? I eat |
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| 12:13 | Oreos. I gotta go grab four Oreos. I eat two more |
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| 12:16 | I have to put two more Oreos the plate. If I throw up |
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| 12:18 | the Oreos, I just ate, gotta take Oreos and I gotta put |
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| 12:21 | back in the pantry. I know was gross, but it goes both |
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| 12:25 | , right? You remember that in basic thermodynamics, right? You |
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| 12:29 | the chemical reactions, both go going ways and that's true in these systems |
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| 12:33 | well. You've got to consider both . All right. But generally |
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| 12:37 | what you put in has to be to what comes out. Now, |
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| 12:41 | thing is, is we don't really understand what the things coming in and |
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| 12:47 | out are. So this process of this equilibrium, that's part of the |
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| 12:53 | . But we have to consider that intake isn't just the food and it's |
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| 12:58 | just the drink, right? The is not just the waste, |
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| 13:02 | The stuff that I pee the stuff I sweat, the stuff that I |
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| 13:05 | . Yeah. You said poop in , right? It's not just those |
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| 13:10 | every time I put something into my that includes the molecules that I |
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| 13:15 | right? So when I'm doing something anabolic in nature, right? I'm |
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| 13:20 | something new. I'm adding something to system. Every time I break something |
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| 13:25 | that's cata bolic, I'm destroying But I'm also in that metabolism, |
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| 13:30 | creating something new, right? So I just think of this, if |
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| 13:33 | have, oh I don't know, a sucrose molecule. What are the |
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| 13:36 | sugars that make up sucrose? You remember? Glucose and the galactose? |
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| 13:42 | . Let see. Notice it was question. It wasn't a, I'm |
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| 13:45 | you, right? So when I that one sucrose molecule and I break |
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| 13:49 | , I've added a glucose and a . I've lost the sucrose. So |
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| 13:54 | an additive effect here as well as subtract effect. And each of those |
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| 13:59 | are things that we need to consider we're dealing with this homeostatic balance. |
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| 14:05 | the law of mass action considers all this stuff. The law of mass |
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| 14:08 | considers all of it all right. loss and gain have to be equal |
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| 14:16 | order to maintain homeostasis, right? you can just think of a day |
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| 14:20 | today, you just walked to camp walked over here. Was it hot |
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| 14:24 | ? Right. Did your body Yeah, your body is now sitting |
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| 14:28 | craving water, right? You're trying add water into the system, |
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| 14:33 | You wanna bring yourself back up into homeostatic balance, right? Because you |
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| 14:38 | it all out. That's the easy . But when you have chemical reactions |
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| 14:43 | you're doing hydrolysis, right? You're removing water from the system. So |
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| 14:49 | would be the example we're looking So here we're looking at a picture |
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| 14:53 | you guys saw from the uh What we're trying to show you here |
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| 14:59 | the different fluid compartments in the You guys all live in a space |
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| 15:04 | has more than one room, Do you have a bedroom? Do |
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| 15:09 | have a bathroom? One person out their head? The rest of you |
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| 15:14 | toilets while your bed? No. . So there's a special place that |
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| 15:18 | go and do your dirty business, ? There's a place where you lay |
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| 15:22 | head to sleep. Is there a in the place where you live where |
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| 15:26 | say for example, Oh, I know, eat your food or prepare |
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| 15:30 | food. Right. Even in dorm you may have things set aside. |
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| 15:34 | is the place where I study, is the place where I sleep. |
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| 15:37 | know, this is the place where hang my clothes. Right. So |
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| 15:40 | have specialized places. These compartments in space are defined by the walls that |
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| 15:48 | created between them. Right now. loft, it's a little bit |
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| 15:51 | but I'm just trying to think of an apartment or a home, something |
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| 15:55 | those lines. All right, your is the same way. In order |
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| 16:00 | it to specialize, it needs to specialized spaces for it to do |
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| 16:05 | And these are these body compartments, ? So for example, a cell |
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| 16:10 | and of itself is a specialized It is a wall, a plasma |
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| 16:14 | that separates a compartment of fluid with chemicals away from the rest of the |
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| 16:20 | in the body with all its And so in that cell, it |
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| 16:23 | do unique things just like you can unique things in the bathroom that you |
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| 16:28 | do in the bedroom. I guess could do them in the bedroom, |
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| 16:30 | we don't want to do that, . We're trying to be honest |
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| 16:34 | right. So we compartmentalize to create specialization and inside the cells, we |
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| 16:40 | compartmentalization as well. And you've learned the parts of the cell, |
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| 16:44 | You learn about your mitochondria and yours and your and all these other fun |
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| 16:49 | , right? You remember all that stuff, right? Those are compartments |
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| 16:53 | that you can create unique chemical reactions as well. So the space inside |
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| 16:59 | cell is referred to as the intracellular . So uh or the fluid inside |
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| 17:04 | cell is referred to as the intracellular . Everything outside of it is considered |
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| 17:07 | fluid. They are unique and different one another. Even though they contain |
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| 17:12 | of the same components. Now between in the in er sorry, in |
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| 17:19 | extracellular fluid, we're gonna compartmentalize we have fluid that's directly next to |
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| 17:25 | cells. And then we have fluid movement fluid that's transporting stuff around the |
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| 17:30 | body. And so the extracellular fluid is is divided into these two separate |
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| 17:36 | and they're separated by the capillary wall . Well, is there to |
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| 17:41 | hey, um not only is this space where I'm moving stuff, but |
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| 17:45 | also preventing certain materials from getting in around the cells that they're not necessary |
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| 17:52 | be around the cells. I need over here because they serve a purpose |
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| 17:56 | the movement of this fluid. So plasma and the uh interstitial fluid, |
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| 18:01 | are these two compartments in the extracellular are unique from one another because the |
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| 18:06 | , while they have all the same and they're interchangeable, the one thing |
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| 18:10 | the plasma has that can't find its over to the interstitial fluid because of |
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| 18:13 | presence of the capillary wall are the proteins. So, plasma and incisal |
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| 18:20 | or if are unique because of those proteins and the plasma proteins not only |
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| 18:25 | a function of the protein, but serve as a way to draw water |
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| 18:29 | the plasma. Right. It's a to bring water back into the |
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| 18:38 | All right. So we've got these portions that are extracellular, we have |
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| 18:42 | portion that's intracellular. Now, one the things I want to clarify in |
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| 18:48 | is this idea of homeostasis and right? Because you'll often hear as |
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| 18:53 | . It's you're in equilibrium. Your is in equilibrium. You're not an |
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| 18:56 | , you're in homeostatic balance. Equilibrium when the two sides of the equation |
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| 19:01 | the same thing and there's no right? It's a chemical term equilibrium |
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| 19:06 | different because if you look, I you to focus down here on the |
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| 19:10 | figure. So the up the upper just basically shows you the three compartments |
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| 19:13 | the one compartment we're not gonna ever about which is trans cellular. We're |
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| 19:19 | gonna pretend it doesn't exist. All . Look down here in the |
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| 19:23 | All right. What do you We got a couple of ions name |
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| 19:28 | ion. Yeah, bicarbonate. Know one. Yeah, it's, it's |
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| 19:39 | that you don't normally see, but one that you're gonna see all the |
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| 19:41 | . So just know it. And here's one that we don't think about |
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| 19:45 | large an anionic cellular proteins. All , this is really what this |
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| 19:50 | All right. So they're large, anionic, if they're anionic, that |
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| 19:54 | they're positive or negative, negative and going to be inside the cell. |
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| 19:59 | that's the thing, right? So at our graph here, here's our |
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| 20:04 | and you can see here that we plasma, we have the intracellular fluid |
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| 20:09 | then we have the intracellular fluid that's stands inside cells if or is for |
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| 20:15 | for plasma. And you can see that while generally speaking, if you |
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| 20:20 | and you measure how much chlorine, much sodium, how much potassium you |
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| 20:25 | in your body. There, you know, it's kind of a |
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| 20:30 | no matter where you go. But you go inside the cells and if |
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| 20:34 | go outside the cells, you're gonna there's a massive imbalance, a massive |
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| 20:39 | and it's sustained. So you can here like it's sodium, it's really |
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| 20:44 | outside of the cells, but inside cells, it's very low. Potassium |
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| 20:49 | the opposite chlorine, very much like , right? Bicarbonate like sodium anionic |
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| 20:57 | proteins. Well, that kind of sense, right? Anionic cellular |
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| 21:03 | they're not the anionic everywhere, they're inside cells, they're like potassium |
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| 21:10 | this disequilibrium, this imbalance is one the ways that our body is able |
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| 21:17 | do all the unique things that it All right. So what we say |
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| 21:21 | , is that inside the outside the , we have an osmotic equilibrium because |
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| 21:27 | you count up the number of solutes caring what they are, you'll see |
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| 21:31 | the inside of the cell and the of the cell are the same. |
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| 21:33 | right, just making up a there's 100 solutes here and 100 solutes |
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| 21:37 | . So there is no movement of , right? Because everything is in |
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| 21:44 | balance, osmotic equilibrium. But it's disequilibrium. I got lots of sodium |
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| 21:50 | the outside of the cell. Very sodium on the inside of the |
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| 21:52 | So what does sodium want to It wants to go down its concentration |
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| 21:56 | into the cell. Potassium lots on inside, very little on the |
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| 22:00 | What does potassium want to do? wants to go out of the |
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| 22:03 | So there is a desire a need meet that equilibrium. So there's a |
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| 22:10 | disequilibrium. You'll also notice that these have charges. This is the part |
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| 22:16 | I fell asleep when I was in seats, right? Oh my |
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| 22:19 | We're gonna talk about ions. Oh . Yes. These charges matter. |
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| 22:24 | right, because that means if we lots of positive ions on the outside |
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| 22:29 | very few positive ions on the that's the same thing as having lots |
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| 22:32 | negative ions, then those positive ions going to move in the direction where |
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| 22:37 | fewer positive ions, right. So is what we would refer to as |
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| 22:41 | electrical gradient as well. That's gonna ions in a direction to bring e |
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| 22:47 | electrical equilibrium. All right. what we call that is we call |
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| 22:55 | current. But if you were to the current of your body, it's |
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| 23:02 | . It's, you're electrically neutral. do I know this? If I |
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| 23:06 | you? Do I become electrocuted? . The only time I get shocked |
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| 23:10 | if I get static electricity built up the surface of my body, so |
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| 23:13 | I rub my feet a little bit come, I can get you. |
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| 23:17 | right. But that's not me. the static electricity on the surface of |
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| 23:20 | body. So we are electrically neutral, but we're an electrical |
|
| 23:25 | We are an osmotic balance but we chemically disbalance or dis equilibrated. All |
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| 23:33 | . And it's our bodies that use create, they first create it and |
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| 23:37 | they use it so that they can the unique stuff that they do. |
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| 23:41 | right. So what we call this a dynamic state, a steady |
|
| 23:45 | What we're doing is we're using the mechanisms of the cells to |
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| 23:49 | hey, if we didn't do sodium would come into balance and then |
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| 23:53 | have equilibrium. But we don't want . We're going to use a pump |
|
| 23:56 | to pump sodium out of the So we build up a lot of |
|
| 23:59 | here and now we have a lot potential energy and I can use potential |
|
| 24:03 | for things. Can you use potential for things? Yeah. Right. |
|
| 24:08 | doing the same thing with the The only one that's not being pumped |
|
| 24:12 | doing anything is that anionic cellular proteins they're large and they're negatively charged and |
|
| 24:17 | stuck inside cells, they can't go . So they're just there and they |
|
| 24:22 | the inside of the cells, they them more negative. So they're actually |
|
| 24:26 | the attraction of those positive charges. right now to get things down those |
|
| 24:35 | , whether it be electrical or chemical collectively referred to as the electrochemical |
|
| 24:41 | All right, I'm gonna have to mechanisms to transport these molecules. And |
|
| 24:44 | reason for that is because of the that sits between the intracellular fluid, |
|
| 24:51 | extracellular fluid. And that's your plasma plasma membrane excite you guys. I |
|
| 25:00 | don't see, I see people give that look. Yeah, that's the |
|
| 25:03 | I had when I got invited to in a lab on the plasma |
|
| 25:07 | And I was like, thank But no, thanks. Yeah. |
|
| 25:11 | , honestly, I didn't get excited the plasma memory until about the fourth |
|
| 25:14 | I was teaching here and I started holy crap. This is the single |
|
| 25:18 | important structure in the body. I , I'm I'm not exaggerating here and |
|
| 25:24 | gonna start seeing this as we go , right? And I understand if |
|
| 25:28 | not excited because I wouldn't be All right. But the point here |
|
| 25:34 | that we need something to allow those , those ions to move between those |
|
| 25:41 | points because the plasma membrane sits in and serves as a barrier to these |
|
| 25:48 | that want to reach equilibrium. And it's a barrier and we have this |
|
| 25:54 | , we have potential energy all over place that we can then take advantage |
|
| 25:57 | . So to exploit that potential I need to have those, those |
|
| 26:02 | . So what is a plasma It's the cell membrane, it's a |
|
| 26:05 | limb and not to be confused with cell wall of a of a plant |
|
| 26:09 | . All right, it is responsible physically isolating the internal space of the |
|
| 26:14 | from the external environment. That's the thing, right? It plays a |
|
| 26:19 | role in regulating the exchange of materials the intracellular fluid and the extracellular |
|
| 26:25 | In other words, it's responsible for what goes back and forth across that |
|
| 26:33 | at your home. Do you have door? Yes. Does that keep |
|
| 26:38 | riff raff out? Small raccoons and ? No, your door doesn't. |
|
| 26:45 | you leave it open, raccoons are be coming. But if you close |
|
| 26:49 | door, raccoons can't come in, ? So it serves as a |
|
| 26:58 | Someone knocks at your door and let me in. You make a |
|
| 27:01 | , right? You can decide whether not to allow them in or out |
|
| 27:06 | the walls and the door stand in way between your internal safe space and |
|
| 27:11 | external unsafe space. As an how do I know whether or not |
|
| 27:18 | should let you in? Well, can communicate across the door, |
|
| 27:23 | And the same thing is happening with cells, those two compartments are |
|
| 27:27 | So they need to have a mechanism allow to know when to do what |
|
| 27:31 | , knock, knock ring the who's there? That's the same sort |
|
| 27:35 | thing that's going on in the So we can communicate across that plasma |
|
| 27:40 | . And finally, it serves as point to structural support. The cells |
|
| 27:45 | independent of each other. They're attached each other, they're attached to |
|
| 27:49 | There are anchors in place to make that the cells don't separate from each |
|
| 27:54 | . So you have a cytoskeleton that the shape of the cell, which |
|
| 27:57 | important. Your cells are shaped the they are shaped to do the jobs |
|
| 28:01 | they're supposed to do, which is supported by the cytoskeleton that's been put |
|
| 28:05 | place. Anyone here, a younger ever gotten an Indian burn? You're |
|
| 28:12 | there going, I don't know, see some people know they had mean |
|
| 28:15 | , older siblings, right? An burn is when someone comes along and |
|
| 28:20 | give me your arm, you grab arm and you twist right and notice |
|
| 28:25 | your cells come falling off your Does your skin come ripping off? |
|
| 28:29 | feels like it. But does The answer is no because all the |
|
| 28:32 | are attached to each other and they this network of attachments from cell to |
|
| 28:36 | to cell to, to uh it just not just the cells but |
|
| 28:40 | to the underlying connective tissue and it the forces that are being applied. |
|
| 28:47 | because the plasma membrane exists. Now I switch aside what a plasma memory |
|
| 28:53 | made up of. Do you guys fossil lipid? Yeah, that should |
|
| 28:58 | the answer. It's like that's the . I'm a biology student. It's |
|
| 29:01 | lipids, it's fossil lipids. Excellent. Yes. These are phospho |
|
| 29:06 | . It is the when you look this thing, you're like, how |
|
| 29:08 | this thing hold together? And these are all physical forces. You |
|
| 29:13 | wonder why you take chemistry when you wonder why you take physics in |
|
| 29:16 | It's because you're like, OK, are forces undergirding all these things that |
|
| 29:22 | this stuff to happen. All So this is just AAA cartoon mockup |
|
| 29:26 | the, of the lipid bilayer. can see it's a, it's a |
|
| 29:29 | . So there's lipids in there, ? They're not attached to each |
|
| 29:33 | they're not covalent linked. Literally, you see a picture of, |
|
| 29:37 | of the membrane, you will see these things are just kind of bobbing |
|
| 29:40 | and down like something on a waterbed right. If you're on the upper |
|
| 29:45 | , the outer facing layer, you're on the outer facing layer. If |
|
| 29:47 | in the lower inward facing layer, stuck on the inward facing layer. |
|
| 29:51 | rare exception when those two things will over. But if you are a |
|
| 29:56 | lipid, you have freedom to move and everywhere in there. Now, |
|
| 30:02 | not just fossil lipids, there's a of other things in there, |
|
| 30:05 | You're not just fat, you're also . All right. So you have |
|
| 30:09 | that are embedded and associated with the membrane and there's also carbohydrates associated with |
|
| 30:14 | plasma membrane as well. Now the , this is one of those things |
|
| 30:20 | like oh OK, the ratio of to lipids as you increase the number |
|
| 30:25 | proteins, that is one of the of an increase in metabolic activity in |
|
| 30:29 | cell. So the more proteins you , the more activity you have the |
|
| 30:34 | proteins you have on the surface of cell or in the plasm membrane, |
|
| 30:37 | less metabolic activity you have. Now are mostly and I'm now we're gonna |
|
| 30:44 | adding a little bit of education, ? These are mostly fossil lipids, |
|
| 30:48 | are other types of lipids in there well, which we're going to go |
|
| 30:51 | a little bit more depth here. , the proteins themselves, they can |
|
| 30:55 | embedded in the membrane. In other , they can pass all the way |
|
| 30:59 | the two bi layers, the two layers are creating an environment that is |
|
| 31:07 | I'm gonna say it this way, it's incorrect. It's basically uh uh |
|
| 31:12 | the presence of water. But it's the opposite water disallows uh fatty acid |
|
| 31:18 | . So that's why the fatty acid move inward. So they're basically being |
|
| 31:22 | from the water. Like a bunch bullies. Water is a bully. |
|
| 31:26 | right. But the proteins can insert and you can see on the in |
|
| 31:31 | you can have one that's sitting on end or they can be partially |
|
| 31:34 | there's different conditions for those proteins and they are associated with that membrane. |
|
| 31:40 | what I wanna do is I wanna focus in on these fos lipids. |
|
| 31:45 | , this is new to you. right. So this is the first |
|
| 31:48 | the phospho lipid. You've seen this before. You have the fatty acid |
|
| 31:52 | . You have the glycerol, you the uh the negatively charged phospho |
|
| 31:55 | You've heard that, right? That's familiar. Have you guys ever looked |
|
| 31:59 | the head in any sort of depth ? So there's your um R |
|
| 32:06 | right? That's the, that's the group. And so there's a lot |
|
| 32:09 | different types of phospho lipids, So you can see here we got |
|
| 32:14 | acid chains, they're excluded from So that's why they affiliate or associate |
|
| 32:18 | so that the heads or the tail poking towards each other. These are |
|
| 32:22 | charged. So, what they're doing they're attracted to the polar molecules of |
|
| 32:26 | . So they're like, oh, wanna hang out with water and the |
|
| 32:28 | are like, but I can't they don't like me and so they |
|
| 32:30 | down and that's, you get enough them and you're gonna get that fossil |
|
| 32:33 | bilayer, right? Do not memorize names of all these, please. |
|
| 32:40 | I wanna show you this because you're start seeing. Oh, wow. |
|
| 32:45 | think I've heard of some of this . All right. So these are |
|
| 32:50 | of four of the most common phospho . Uh You guys recognize serene. |
|
| 32:56 | sea? It's an amino acid, ? Notice it's attached to the |
|
| 33:01 | You guys heard of Cole? Thank . Thank you. You guys taking |
|
| 33:10 | , right? Where do you think Cole from acetyl Cole comes from? |
|
| 33:14 | gonna go ahead and sacrifice this thing gets exchanged back and forth. Um |
|
| 33:19 | not, I have no idea. never seen it. I'm not even |
|
| 33:25 | say it right now. It's it's not gonna roll off. Uh |
|
| 33:29 | . There we go. Ethanolamine. you. All right. Anyone seen |
|
| 33:33 | one? No. All right. put a little asterisk by that |
|
| 33:42 | Not to memorize. Just put Say he's gonna come back to that |
|
| 33:47 | . All right. Probably in two . All right. And you're gonna |
|
| 33:51 | like, oh, now I All right. No. So what |
|
| 34:00 | you notice about all of these Do they look different from one |
|
| 34:04 | What do they all have? They the polar head, they have the |
|
| 34:10 | fatty acid tails. They have a backbone. They look all alike and |
|
| 34:14 | how you've learned it your entire But you've never ever focused on those |
|
| 34:18 | . It's those heads that make them and those heads are used in chemical |
|
| 34:23 | . Right. That one of which we're gonna talk about. Hence |
|
| 34:27 | asterix. All right. So they're just as we would say, a |
|
| 34:33 | of fossil lipids in a uh they're there for a reason. They |
|
| 34:39 | functionality, but for the purposes of plasma membrane, they serve as our |
|
| 34:46 | . Second lipid, ever heard of one? Sfo lipid. What does |
|
| 34:52 | look like here? I'll go back slide. It looks like a fossil |
|
| 35:08 | . It's not a fossil lipid, it looks like one. All |
|
| 35:12 | what it is is a fatty acid . There's your fatty acid tail. |
|
| 35:17 | then up here, this is called fa F is a mean alcohol. |
|
| 35:24 | right. Now, ask me what mean? Alcohol is and that's about |
|
| 35:27 | far as you go. All I'm not a chemist, right? |
|
| 35:31 | the idea here is you can start here what does it have? It |
|
| 35:34 | a characteristic shape similar to a phosphor . So if it has a shape |
|
| 35:39 | a phospho lipid, how do you it behaves like a phospho lipid. |
|
| 35:44 | it looks like a duck and quacks a duck, it's probably a |
|
| 35:47 | All right. It's not a but it's a lot like a |
|
| 35:50 | It's like a goose. How's All right. Now, here it's |
|
| 35:56 | have the same thing. The difference , is while you can find them |
|
| 35:59 | the membrane and they kind of behave phosphor lipids, they tend to hang |
|
| 36:02 | with each other and they form what called these lipid rafts. Have you |
|
| 36:06 | heard of a lipid raft? They of sit up, they're a little |
|
| 36:10 | taller than the other phosphor lipids and kind of congregate with them and they |
|
| 36:14 | together and then you end up with big giant raft that's just kind of |
|
| 36:17 | along on the, the river or pool of fossil lipids. That's just |
|
| 36:23 | lipids. That's what they kind of . So we have two kind of |
|
| 36:27 | that look like phospho li what one and one look kind of looks like |
|
| 36:30 | and they kind of behave the same . And then we have the cool |
|
| 36:34 | , the one that I was told entire life were terrible for you. |
|
| 36:37 | do not eat them. Is this best lipid of all? Mm |
|
| 36:46 | All right. Cholesterol is an incredibly , valuable lipid. All right. |
|
| 36:53 | off, you can see the shape there. Why I think it's important |
|
| 36:55 | to give you a background. My is in reproductive physiology. All |
|
| 37:00 | When we get to reproduction, you'll me like a little school kid. |
|
| 37:02 | be up here all day long. kind of doing. Oh, let |
|
| 37:05 | tell you stuff that you should know not on the test. All |
|
| 37:10 | But one of the things I had uh work with and deal with our |
|
| 37:14 | , androgens primarily is what I worked , but also some of the |
|
| 37:18 | All right. Well, cholesterol is backbone. It's the, it's the |
|
| 37:22 | block to make all those steroids. so this structure is exciting to me |
|
| 37:26 | I've been working with it forever. it's exciting for you is because what |
|
| 37:31 | does to your cells, see when go and look at a lipid or |
|
| 37:35 | fossil lipid, those fatty acid these, they're showing you here are |
|
| 37:39 | , right? But if you have unsaturated fatty acid, what's gonna happen |
|
| 37:42 | those fatty acid chains aren't gonna be down like this, they're gonna kink |
|
| 37:47 | to the side. And if you a bunch of people with straight legs |
|
| 37:50 | next to each other, they get nice and close and they stiffen up |
|
| 37:54 | you make really, really dense right? You, you know, |
|
| 37:58 | fat, I, I have a of dense fat. All right. |
|
| 38:02 | then if you have a lot of , you can't get close together. |
|
| 38:06 | you end up with a lot of fat. And so you can imagine |
|
| 38:09 | plasma membrane that has too much looseness one that's a very, very leaky |
|
| 38:15 | membrane. And if you have plasma that have too many fat phosph lipids |
|
| 38:19 | are, are jammed together with saturated , then you have a dense plasma |
|
| 38:24 | , nothing can ever get through. so what these do is they sneak |
|
| 38:29 | between in those spaces. So wherever is a kink, they kind of |
|
| 38:34 | in there and they make something that's , more solid and where there's something |
|
| 38:40 | really, really dense, they get between, they break it up and |
|
| 38:43 | make it more liquidy. And what means is is that under temperature |
|
| 38:50 | the condition of the fats changes state is is able to maintain its state |
|
| 38:56 | a longer period of time or in over a longer range. Now, |
|
| 39:00 | put this in perspective here. Uh you take butter, what is |
|
| 39:03 | Is it a solid or a liquid ? So how do you turn it |
|
| 39:07 | a liquid? Heat it up? it in a grill, right? |
|
| 39:10 | just watch it melt down real quick you have something like um oh, |
|
| 39:14 | don't know, uh I don't vegetable oil, which is liquid or |
|
| 39:20 | . But if you put in the , it becomes a Yeah, if |
|
| 39:23 | buy country crock or any of those things in our margin. That's whipped |
|
| 39:28 | oil, kept cold in a solid . Leave it out on the counter |
|
| 39:32 | an hour and see what happens. just like now I got vegetable |
|
| 39:37 | All right. So they have a range in which they can become |
|
| 39:40 | or solid. Right. What cholesterol is it broadens that range? So |
|
| 39:45 | when it becomes hot, your cells melt and when it becomes cold, |
|
| 39:51 | cells don't become solid, you're able survive in a broader range of |
|
| 39:57 | kind of cool, which is why think cholesterol is cool. All |
|
| 40:02 | So it provides flexibility over a broader is what we're kind of getting at |
|
| 40:06 | . Now it is a fat so hides wherever the fats are. So |
|
| 40:09 | hangs out with the fatty acids. are different types of membrane proteins. |
|
| 40:17 | can be a little frustrating picture sometimes it's like, OK, I got |
|
| 40:20 | proteins. These are loosely associated to proteins which we'll define here in a |
|
| 40:25 | . So here you can see here a peripheral protein, peripheral protein down |
|
| 40:29 | in the blue. And it oh, or it could be attached |
|
| 40:31 | the polar heads and you see this here and say, wait, there's |
|
| 40:33 | polar head that's attached. No, this is a different type, this |
|
| 40:36 | lipid anchored. But you could have example, an uh a peripheral protein |
|
| 40:42 | of hanging out with the polar So like like attracted to the |
|
| 40:47 | attracted to the searing through the uh uh non covalent bonds. Um, |
|
| 40:55 | you might find between any two All right. So that would be |
|
| 40:59 | example of a peripheral protein. It's the periphery. All right. This |
|
| 41:05 | the first, I'm gonna say it . Well, at least in this |
|
| 41:09 | , um I will say it over over again, probably twice a |
|
| 41:12 | Maybe if you ever get lost or in biology, not just his class |
|
| 41:18 | biology in general. Just remember, are simple people. We're not |
|
| 41:23 | I make fun of chemists every single . Ok. Ok. We're not |
|
| 41:27 | . We name things for what they or for what they look like. |
|
| 41:30 | if you ever look at something you're , I have no idea what this |
|
| 41:33 | . Stop, take a step back see if you can break down the |
|
| 41:37 | , right. It will usually tell exactly in the name of what it |
|
| 41:40 | or what it does. And if doesn't, it's usually because you weren't |
|
| 41:43 | when they named it. So you know, something like an astrocyte |
|
| 41:47 | sense because it's like, oh, astro is a star. So an |
|
| 41:53 | is a star cell. So why you think they call it a star |
|
| 41:57 | because it was discovered in Houston? , no, it's because it looks |
|
| 42:01 | a star, right? You're right it looks like a star. That |
|
| 42:05 | sense. Right, you don't have like dive deep into kind of figure |
|
| 42:08 | some of these things. All But here's an example. Why is |
|
| 42:12 | called a peripheral protein because it's on periphery? Why is it an integral |
|
| 42:17 | because it is integrated? All don't. And I know these are |
|
| 42:21 | examples, but I just saw Don't let yourself become your own impediment |
|
| 42:28 | the learning process going. This has to be hard because it's supposed to |
|
| 42:31 | hard. Now, biology is not hard. None of this three comma |
|
| 42:38 | dash N, methyl dash dash, of that stuff. And yes, |
|
| 42:42 | know there's an actual pattern to the , but it's hard. And I |
|
| 42:47 | to make fun of chemists, integral , integral proteins are proteins that penetrate |
|
| 42:53 | the plasma membrane. You can see we're going all the way through, |
|
| 42:56 | over here we're not, those are integral because they are penetrating into the |
|
| 42:59 | lipid bilayer. All right, they're named based on the number of membrane |
|
| 43:04 | portions of their sequence that actually penetrate . So what we refer to as |
|
| 43:09 | transmembrane region. So this would have single uh transmembrane region. This one |
|
| 43:14 | three, this one has one. . But the idea is is there's |
|
| 43:19 | portion that goes in and through. so that region has the same features |
|
| 43:24 | that the, the, the fatty tail. So basically, it's non |
|
| 43:29 | And so it wants to hide in non polar environment. And that's what |
|
| 43:33 | holds it in place. Typically, proteins are free to move about unless |
|
| 43:38 | attached to something that doesn't let So they are free to roam. |
|
| 43:44 | just like the fossil lipids, they move wherever they go. There's no |
|
| 43:47 | linkages amongst the, the stuff that's that plasma membrane um on the outside |
|
| 43:54 | on the inside. So you can here and there that's an extracellular loop |
|
| 43:58 | would be an intracellular loop. This it to interact with other proteins. |
|
| 44:02 | so this is one of the mechanisms the cell uses to play uh to |
|
| 44:06 | messages and to send messages. In words, to have the external |
|
| 44:10 | tell the cell what to do internally vice versa. Right. So they |
|
| 44:15 | with other proteins through these uh excellent loops. I did mention you know |
|
| 44:24 | they can move freely, but if , they can also be attached to |
|
| 44:28 | cytoskeleton and when they are, that's they're not allowed to move, they're |
|
| 44:31 | as an anchor point. And that's also helps to uh create structure and |
|
| 44:37 | is through those cyto skeletal anchors, anchored proteins. You're gonna see a |
|
| 44:42 | link between the lipid. So here can see there is the tails, |
|
| 44:46 | the gl- glycerol, there's a phospho here, we can see a sugar |
|
| 44:51 | then another phospho region that's attaching the that the proteins attached to. All |
|
| 44:57 | . And so in this case, is what is a lipid anchored |
|
| 45:00 | what is usually called a GP um because it's, there's some sugar |
|
| 45:04 | usually involved here. All right. And so the idea here is I |
|
| 45:11 | able to attach myself and embed myself the membrane because of that attachment to |
|
| 45:18 | fossil lipid or the single lipid. right, those are the lipid anchored |
|
| 45:23 | . And again, the name should it away. So what I want |
|
| 45:27 | do is I want to kind of through a bunch of different classes really |
|
| 45:30 | . And you may see, I know, sometimes they may be named |
|
| 45:33 | here, but we're more interested in class. All right. And so |
|
| 45:37 | throw this one up first because one particular type of molecule right here, |
|
| 45:43 | , this picture is the single, common type of brain protein that you'll |
|
| 45:48 | in the body. All right, the seven transmembrane protein. Uh what |
|
| 45:52 | usually see is referred to as the protein coupled receptor, which we'll spend |
|
| 45:56 | lot of time talking about. You about 5000 different ones of these and |
|
| 46:01 | of them are in your nose. play the role in the sense of |
|
| 46:04 | , you know, but that's not only place you find them. All |
|
| 46:07 | . So here you can see in ligand binding receptor class. So this |
|
| 46:12 | a two dimensional look. This would like a three dimensional look. So |
|
| 46:14 | can see it's not just spread it's actually pretty compact. You have |
|
| 46:18 | region that's on the external side, for binding a signaling molecule. Um |
|
| 46:23 | it causes when anything binds here, going to cause a change in the |
|
| 46:26 | of the intral or the uh the uh binding site which is usually associated |
|
| 46:33 | some other molecule. The change in shape of the outside causes change on |
|
| 46:36 | shape of the inside which any time have a change in the shape of |
|
| 46:40 | molecule causes um a change in the . And so you can turn things |
|
| 46:45 | and turn things off this way. right. So for the most |
|
| 46:50 | the region that's outside is called the binding protein or the lion binding |
|
| 46:55 | Um a ligand if you've never heard term or maybe you heard it, |
|
| 46:58 | you didn't know what it means. just means the signal, something that |
|
| 47:01 | bound is the best way to think it. So the ligand binding region |
|
| 47:06 | the region that binds the thing that . They play a major role in |
|
| 47:12 | chemical messaging. They also play an role in vesicular transport, which we'll |
|
| 47:16 | with on another day adhesion molecules. is your molecular um velcro this is |
|
| 47:26 | cells hold each other together. And again, you can see we have |
|
| 47:29 | membrane sections. Here, you can outside the cell, there's usually a |
|
| 47:33 | extracellular matrix made up of a whole of unique and interesting proteins which we're |
|
| 47:37 | going to go into to. But here, you have something that's in |
|
| 47:41 | membrane and it's anchoring itself to this and it may have something intracellular that's |
|
| 47:46 | of the cytoskeleton that's holding it in . And so now you have basically |
|
| 47:50 | anchor point for the outside uh uh and the inside matrix. So that |
|
| 47:56 | is not going anywhere. And very this can be used as a way |
|
| 48:01 | two cells to talk to each So it's not just attaching cells together |
|
| 48:07 | the cell or maybe even to a to hold it in place, like |
|
| 48:10 | in the connective tissue. But it serves as a way for cell to |
|
| 48:15 | communication. Um Some of these might just like those GP is that I |
|
| 48:21 | you the lipid anchored proteins, what gonna spend most of our time today |
|
| 48:26 | gonna be on these transporters. And this is another very common type. |
|
| 48:31 | are two basic categories. We got and we have carriers. All |
|
| 48:36 | So what's a channel? It's basically door. All right. What's the |
|
| 48:41 | of a door, that door over ? What's at state closed? All |
|
| 48:46 | . If we go over there and it up and it's now open, |
|
| 48:48 | doors can be either in a closed or an open state, can we |
|
| 48:52 | that door open and keep it Yeah, when we do that, |
|
| 48:55 | call it a poor, right. typically speaking channels will have always have |
|
| 49:01 | sort of gate, right. So basically a door with disc gates. |
|
| 49:07 | if it's a channel, we will refer to it as a channel because |
|
| 49:11 | opening and closing. And if it a poor, that means basically the |
|
| 49:16 | the gate has been propped open and open. All right, we also |
|
| 49:21 | carriers and what they do. I should say what channels do. |
|
| 49:24 | allows for the materials, these very, very small particles, not |
|
| 49:31 | things, right? We're literally talking ions to be able to pass back |
|
| 49:36 | forth between the extracellular fluid and intracellular . So this is how these ions |
|
| 49:41 | able to move freely between those two . They can diffuse simply by moving |
|
| 49:47 | their concentration gradient or their electrical The carrier. On the other |
|
| 49:53 | all right. So the carrier is for binding two in a non covalent |
|
| 50:00 | , a substance and then surrounding it that it can be brought to the |
|
| 50:04 | side of a membrane. Now, channel is easy to envision because we |
|
| 50:10 | look at a door like that and . Yeah, I see that that |
|
| 50:12 | and closes. Carry is a little harder to envision. But you've all |
|
| 50:17 | to say a hotel that has the spinny door or maybe an airport |
|
| 50:22 | has the large spinny door. If haven't go to the Hilton school, |
|
| 50:25 | have a large spinny door. And you can, you envision that |
|
| 50:29 | walk up to the door and here has that big giant thing with the |
|
| 50:34 | partitions. And you're like, I've got to time myself and then |
|
| 50:38 | get in there and you get into little space and then you're just kind |
|
| 50:41 | like going around with it, you , like, OK, I'm gonna |
|
| 50:43 | around and it's like, OK, got to the other side. That's |
|
| 50:46 | a carrier works. You're never I mean, you're either on the |
|
| 50:50 | or the inside or you're in between two states, right? You're, |
|
| 50:55 | that point when you're in that spinny , I don't know what kind of |
|
| 50:58 | it's called. If you have a name for it, let me |
|
| 51:01 | Right. But there's a point where not exposed to either the inside or |
|
| 51:05 | outside, there is a middle state it's because you're being protected from that |
|
| 51:12 | environment or that non polar environment because molecule itself is basically opening in that |
|
| 51:19 | . Now, if a carrier or should say, if a, |
|
| 51:22 | if a carrier takes a molecule that's down its concentration and it's doing so |
|
| 51:30 | the use of energy. In other , not neither direct or indirect, |
|
| 51:34 | just something's moving down its concentration we just refer to the molecule as |
|
| 51:39 | as a carrier. But if I'm a molecule against its gradient, |
|
| 51:47 | So energy is being used either directly indirectly, we call this a |
|
| 51:54 | Does that make sense? So if have to use energy, I'm pumping |
|
| 52:00 | , right? If I want to water from down here to up |
|
| 52:03 | what do I have to do? have to use a pump, |
|
| 52:05 | And that's sort of the same It takes energy to move something against |
|
| 52:09 | natural inclination, things wanna move down concentration gradients. So in order to |
|
| 52:14 | it down its co uh against its gradient upward, I have to apply |
|
| 52:20 | either directly or indirectly. So that's a pump is needed. We're gonna |
|
| 52:25 | many examples of these by the end class other types of membrane proteins, |
|
| 52:32 | will see things that play a role intracellular signaling. So this is gonna |
|
| 52:36 | a G protein uh G protein coupled pathway we're gonna look at and you |
|
| 52:40 | see here we got proteins. Um is phospholipase C you hear that word |
|
| 52:45 | you're like ah big word fossil What do you think? It breaks |
|
| 52:50 | lipids? Right? Ace is an . The first part of the word |
|
| 52:54 | phospho lipid ace. So there you , phospholipase, it's ac. So |
|
| 53:00 | you have a molecule that it begin ac in it. Do you think |
|
| 53:03 | there's a molecule that's a phosph or A? You think there's a |
|
| 53:09 | yeah, if you have ac, probably have the A and the |
|
| 53:12 | all right. And that's gonna be , kind of going the other direction |
|
| 53:15 | well. Um, here we got K AC. All right. |
|
| 53:20 | these are all proteins that they're showing the little squiggly showing that they're involved |
|
| 53:27 | , or associated with that membrane. they're found on the intracellular side. |
|
| 53:32 | so what they're doing is they're taking external signal and they're turning it into |
|
| 53:37 | internal signal. So those do All right. Nothing's just limited to |
|
| 53:43 | outside. We got enzymes. And just showed you an enzyme, phosph |
|
| 53:47 | PC is an enzyme. It's breaking phospho lipid. Uh I remember how |
|
| 53:51 | said, put that asterisk up. right. Remember phospho phospho tino, |
|
| 54:00 | PP two phos nool, you break , you get PP two, that's |
|
| 54:08 | , nool di phosphate and you get other half which are the two fatty |
|
| 54:14 | , you break it. I'm If you break it, you get |
|
| 54:16 | three, it's a nool trios. dag, that's the two tails and |
|
| 54:20 | Glycerol, Diy Glycerol. So we a fatty acid stuck in the |
|
| 54:26 | We add an enzyme to it. cleave it. We get two parts |
|
| 54:29 | now we have a whole pathway that's activated. They're not just sitting in |
|
| 54:34 | membrane that's what I'm trying to get . So we got enzymes, they |
|
| 54:38 | do all sorts of fun stuff. then we mentioned also the cytoskeleton. |
|
| 54:42 | this is an example of that. , a whole bunch of proteins, |
|
| 54:44 | don't care about their names. But can see right here, there's acting |
|
| 54:48 | then there's other uh small uh uh uh proteins that are basically creating a |
|
| 54:54 | that's creating a structure that maintains the of the cell so that it can |
|
| 54:58 | its job. So we're organizing the membrane. In essence, I know |
|
| 55:08 | going hard and fast. I'm just to get through this stuff because it's |
|
| 55:12 | always particularly interesting. Are you like excited? I saw you not like |
|
| 55:16 | . It's not interesting at all. right. Are there questions so far |
|
| 55:21 | this? So basically, what we've so far is that there's a plasma |
|
| 55:25 | that separates an internal and external There's things that it's made up of |
|
| 55:30 | and me and membrane proteins. I spoke for an hour on that. |
|
| 55:36 | that crazy? I wait till I to reproduction. You'd be like, |
|
| 55:40 | you kidding me? I used to a reproduction class 27 lectures on |
|
| 55:48 | Can you imagine? I thought it just get in, get out and |
|
| 55:51 | done. That was a joke. right, I can wake you |
|
| 55:58 | All right. The last thing. we are made up of not only |
|
| 56:03 | , not only fat, but we have sugars that make up the uh |
|
| 56:07 | are found associated with the plated This is called collectively the glyco |
|
| 56:13 | All right, the glyco Cali refers the sugars that are attached to any |
|
| 56:18 | the proteins and sugars that are attached any of the phospho lipids. So |
|
| 56:24 | I attach a sugar to a phospho , I call it a glycolipid. |
|
| 56:27 | I attach sugar to a protein, call it a glycoprotein. And so |
|
| 56:32 | glycoprotein and the glyco lipids are collectively on each of the surface of the |
|
| 56:38 | . They're only found on the external and they create a unique um external |
|
| 56:44 | for each of the cells. Your is unique to you and to no |
|
| 56:50 | else, which is kind of If you are an identical twin, |
|
| 56:56 | do not share glycolic. It's how cell can identify one of the ways |
|
| 57:01 | cells can identify self cells. So of your cells are candy coated. |
|
| 57:12 | right. So it's a highly specific marker that the cell uses to identify |
|
| 57:19 | . And so you can see in little cartoon again, it's a bad |
|
| 57:22 | . So all the green stuff. are the unique glyco um lipids and |
|
| 57:27 | proteins that make up that glycolax. what I wanna do is I want |
|
| 57:36 | change and shift gears and I wanna to, how do I move |
|
| 57:40 | Because remember we created a wall. we wanted to talk about the wall |
|
| 57:44 | . So how do I move things either side of the wall? That's |
|
| 57:48 | of important, right? So the common form of movement of materials in |
|
| 57:54 | body is something called bulk flow. just want to get it out of |
|
| 57:57 | way because it's, it's kind of easy thing to do and we'll get |
|
| 58:00 | out the way and we're gonna come to it. We talk about the |
|
| 58:02 | system, the respiratory system, when breathe in, you breathe out. |
|
| 58:06 | are you breathing air? Right? it, what, what of air |
|
| 58:12 | your body want in oxygen? What it not want in carbon dioxide? |
|
| 58:17 | want to get rid of it. when I breathe in, I'm pulling |
|
| 58:21 | air which is nitrogen, about 80% , which is about 20% I said |
|
| 58:28 | and then carbon dioxide, which is 0.2%. And then all sorts of |
|
| 58:32 | things down the list that we can through the noble gasses and the dust |
|
| 58:36 | the smog and the pollution and the and the bacteria and everything else out |
|
| 58:42 | that can be floating around, including because we live in Houston and we |
|
| 58:46 | a human environment. All right. all that stuff is in air. |
|
| 58:50 | the only thing my lungs and my wants is oxygen. But when I |
|
| 58:55 | in, I bring it all in bulk flow. And when I push |
|
| 58:59 | that's bulk flow as well, when talk about the exchange of materials between |
|
| 59:04 | and the rest of the body, ? So if I'm taking oxygen to |
|
| 59:07 | cells, if I'm taking glucose to cells, or if I'm creating metabolic |
|
| 59:11 | and including carbon dioxide, I'm taking , things from the cells and I'm |
|
| 59:15 | them out into the blood. So from the blood going to the |
|
| 59:18 | things from the cells going out to blood with the interstitial fluid serving as |
|
| 59:22 | middle man. I'm going to move down pressure gradients. So not with |
|
| 59:29 | in and out. What I'm doing I'm changing the pressure of my thoracic |
|
| 59:33 | . And so pressure is the driving behind bulk flow. It does not |
|
| 59:38 | itself with what it's moving, it's creating pressure so that things move with |
|
| 59:43 | pressure gradient. Ok. So that's form of movement and we'll see it |
|
| 59:51 | at least twice once in the once in the respiratory system. All |
|
| 59:57 | , what we're concerned about is what's on at the level of the |
|
| 60:02 | See bulk flow doesn't occur across the because the membrane itself has a certain |
|
| 60:07 | of permeability to it. All when we say something is permeable, |
|
| 60:11 | we're saying is that it allows for passage of a specific material. All |
|
| 60:16 | , if we say a membrane is , we're saying it doesn't allow |
|
| 60:21 | And so when we talk about our per our cell membranes, what |
|
| 60:25 | saying is that it's not just permeable impermeable, that it's permeable to some |
|
| 60:30 | , but it's impermeable to other And so collect if we go through |
|
| 60:34 | entire list where we go. well, it, it has a |
|
| 60:38 | for certain things and a dis preference a lack of preference for another. |
|
| 60:42 | it is selective in what it allows pass back and forth across membrane. |
|
| 60:46 | it is selectively permeable. That selective is again, it's dependent upon a |
|
| 60:52 | of things. It it's dependent upon the soluble of the molecule that you're |
|
| 60:57 | at. And the solubility, what do is we just have to consider |
|
| 61:00 | or the other. Are we gonna about its solubility in lipid or we're |
|
| 61:03 | talk about solubility in water? You , get to choose what you want |
|
| 61:06 | talk about. I prefer talking about because they're the ones that are in |
|
| 61:09 | way. And that's what the membrane made of, right. So if |
|
| 61:12 | have something that's soluble in lipids, wall of lipid is not, is |
|
| 61:17 | gonna stop it from moving through Is it does that make sense? |
|
| 61:21 | in other words, if I'm lipid and I'm coming across a wall of |
|
| 61:27 | , that means I can go right through, right? I allow the |
|
| 61:32 | of those types of materials. But I'm not soluble in lipid, when |
|
| 61:37 | come across a plasma membrane that's made of lipids, I can't pass |
|
| 61:43 | It is a no go zone. so that's the first thing we have |
|
| 61:47 | consider is what is our permeability So things that are uncharged like |
|
| 61:52 | carbon dioxide, things that are non . In other words, lipid |
|
| 61:57 | they're just gonna go right on So water can pass right on through |
|
| 62:01 | plasma membrane. Well, not Excuse me, oxygen carbon dioxide, |
|
| 62:06 | is something weird. I'm gonna address in just a moment. But oxygen |
|
| 62:09 | dioxide just move down their concentration gradients wherever they want to go kind of |
|
| 62:15 | . All I gotta do is supply oxygen and my cells will get the |
|
| 62:18 | . Yeah, the speed at which get is gonna be dependent upon the |
|
| 62:21 | in which that oxygen arrives. Size . If I have big molecules, |
|
| 62:29 | molecules are hindered in their movement. I have small molecules, they can |
|
| 62:33 | around all over the place. So smaller the molecule, the easier it |
|
| 62:37 | for me to slip between two phospho . You ever take care of a |
|
| 62:43 | sibling or if you have a I have four kids, two sets |
|
| 62:51 | twins and you know what twins like do, they like to go in |
|
| 62:55 | direction, right? And I remember at a place where my son let |
|
| 63:00 | of my hand and off he went legs. Now, I'm a big |
|
| 63:06 | . I can't go between legs and who's three years old and is this |
|
| 63:10 | , can go through a lot of really, really quickly. Right. |
|
| 63:15 | matters. So, the smaller the , the easier it is to move |
|
| 63:19 | kids are gas molecules, by the , what sort of force is necessary |
|
| 63:27 | move that thing? All right, something doesn't require any sort of energy |
|
| 63:33 | it to move. In other it's just moving following the natural |
|
| 63:36 | concentration, electrical, that's a passive . All right. So we need |
|
| 63:42 | consider is this passive or is it in a direction that it doesn't want |
|
| 63:46 | go? This is what we refer as something as being active. It |
|
| 63:50 | a TP, the energy released from TP in some way, whether it's |
|
| 63:54 | to be directly acting on the molecule moves it or maybe you're using a |
|
| 63:59 | to create a gradient to force that that would be an indirect. So |
|
| 64:04 | can do either of those two So what we say is there's different |
|
| 64:08 | of movement, right? Any type transport, we have diffusion, we |
|
| 64:13 | what is called membrane transport and the transport. And then osmosis and |
|
| 64:18 | very brief nutshell diffusion is simply the of a molecule. So if it's |
|
| 64:24 | diffusion, we're saying we don't even a protein to do it a simple |
|
| 64:28 | is the molecule just moves. All . And that's what the next slide |
|
| 64:33 | is. When we're talking about a of a protein, this is gonna |
|
| 64:38 | some sort of diffusion that is So if it doesn't require energy, |
|
| 64:44 | refer to it as being passive. if it requires energy, we call |
|
| 64:48 | active diffusion or active transport is the that we commonly use. If we're |
|
| 64:54 | about water diffusion, that's what we osmosis. So any definition you've heard |
|
| 65:00 | osmosis that confuses you throw it away just say it is water diffusion, |
|
| 65:06 | water moving down its concentration gradient, end and I promise you everyone will |
|
| 65:13 | to confuse you with that definition. then we have the secular transport where |
|
| 65:17 | basically saying things are too big. we're gonna put things in a bubble |
|
| 65:20 | we're gonna move things literally across the by adding or subtracting from the |
|
| 65:26 | So here's simple diffusion right here. is stuff that you've been learning since |
|
| 65:30 | beginning of time. You throw a cube with dye in it or die |
|
| 65:34 | into water. They're all concentrated next each other. Everybody wants their elbow |
|
| 65:38 | , right? No one knows how got. When you came in the |
|
| 65:40 | , you guys kind of moved around said, I'm gonna find the most |
|
| 65:43 | around me as I possibly could. then someone sat next to you that |
|
| 65:49 | person is just weird but mostly what try to do is we try to |
|
| 65:54 | an equal space between all of And that's what the molecules are trying |
|
| 65:57 | do in diffusion. They're basically running each other, an equal rate so |
|
| 66:01 | they spread out equally. And that's equilibrium takes place. So diffusion is |
|
| 66:05 | to reach that steady state where there molecules equally distributed amongst the space that |
|
| 66:12 | found in. So this is right? You're always gonna move from |
|
| 66:19 | area of high concentration, an area low concentration, we refer to the |
|
| 66:26 | of molecules uh between the two So if you look at area A |
|
| 66:30 | B, more molecules are moving from to B than B to A. |
|
| 66:34 | there are things moving from B to , the difference between that is our |
|
| 66:38 | diffusion. All right. So just there's few over there like they're |
|
| 66:42 | oh OK, I'm fine over they will migrate and move around all |
|
| 66:46 | the place is just the probability of moving from A to B is greater |
|
| 66:50 | B to A. But when everything out, that's when you have that |
|
| 66:54 | diffusion or not, when you equal , when you're considering both those |
|
| 66:59 | there's greater movement in one direction. that would be the net diffusion. |
|
| 67:04 | takes is faster under certain conditions. you increase the slope, right? |
|
| 67:10 | make put more over here and less here, you're gonna go faster. |
|
| 67:14 | easy way to remember this. And is kind of hard in Houston. |
|
| 67:16 | if you get on a skateboard on flat surface, do you move? |
|
| 67:20 | . But if I create just a slope, is that skateboard gonna move |
|
| 67:24 | I wanna go faster. What do do make that slope slopes deeper? |
|
| 67:28 | a concentration rate. Put more over , they're gonna go faster, that |
|
| 67:32 | . That's number one second thing, distances, right? If I have |
|
| 67:37 | travel a long distance, that rate dis slows down. If I have |
|
| 67:41 | short distance it goes up. Here's one pathology, pneumonia. You guys |
|
| 67:46 | know what pneumonia is, right? , it's a condition usually through an |
|
| 67:50 | that causes a build up of water on the inside of the lungs. |
|
| 67:54 | distance between the inside of the capillary the inside of the alveoli is about |
|
| 67:59 | 0.1 microns. It's very, very . But if you put just a |
|
| 68:04 | of molecules of water, you increase distance. If you double it, |
|
| 68:07 | reduced the rate of diffusion for oxygen carbon dioxide across that membrane because it |
|
| 68:13 | has to cross, not just but that water. That's why pneumonia |
|
| 68:17 | so debilitating because you have a hard moving the air, you need to |
|
| 68:21 | yourself alive, really the oxygen. um higher temperatures, this should make |
|
| 68:27 | if I add energy, temperatures, , right? If I increase the |
|
| 68:31 | of energy I put into the the faster the molecules are gonna bump |
|
| 68:33 | each other. Help you remember I see a couple of heads |
|
| 68:38 | This is good. Most people stare me at this point and I know |
|
| 68:41 | watching the time here. All Um If I take iced tea and |
|
| 68:46 | sugar in it, where does the go down to the bottom? So |
|
| 68:50 | do I mix in the sugar? add an energy, right? I |
|
| 68:54 | it up. How do you guys how to make sweet tea? Good |
|
| 68:58 | Southern recipe. What do you Boil the water and then you put |
|
| 69:03 | sugar in, right? So you've added the energy. So the sugar |
|
| 69:07 | oh and it moves all around, the difference. OK. So this |
|
| 69:14 | how you increase the rates of All right, diffusion can take place |
|
| 69:20 | an open system like we're seeing But if you put a partition |
|
| 69:23 | all you got to ask the question , is there permeability for that? |
|
| 69:27 | if you put a membrane in so like here, if those little |
|
| 69:29 | or those little dots represent water and put a membrane in there, that's |
|
| 69:33 | to water, then that's diffusion can that. But if you put um |
|
| 69:38 | uh a membrane in there, that's permeable to water, you're not gonna |
|
| 69:41 | simple diffusion. OK? You'll need sort of carrier, some sort of |
|
| 69:46 | to allow that to happen. Fixed is just something you should be kind |
|
| 69:52 | aware of. It basically describes all different things. So concentration gradient is |
|
| 69:57 | , as we mentioned, permeability of substance, the greater the permeability. |
|
| 70:01 | other words, the more chances that could get across the faster it'll |
|
| 70:05 | What's the surface area? Is it ? Is it small think of the |
|
| 70:09 | ? How many people can you fit the door at the same time? |
|
| 70:12 | at that door. What do you ? 1236, probably two, at |
|
| 70:19 | one. Definitely one, you questionable for maybe me but you |
|
| 70:25 | yeah thickness. So how far does have to travel? I don't know |
|
| 70:32 | I throw this slide up here I think it's because about it but |
|
| 70:37 | is what you're what you're looking at . This math, this horrible stuff |
|
| 70:40 | you're looking at going. Do I to know this and do I have |
|
| 70:42 | apply it on the exam? The is no, we teach you nurse |
|
| 70:45 | equation because what this does nurse equation you to see where equilibrium is gonna |
|
| 70:52 | met across the membrane when it comes something that has a charge to |
|
| 70:58 | So we know already that something wants move down its concentration gradient. But |
|
| 71:04 | are the things that are moving the and they also have an electrical gradient |
|
| 71:07 | moves in the opposite direction. That do. All right. So every |
|
| 71:12 | I move a positive ion from here here, I'm basically taking a charge |
|
| 71:17 | . And so now that charge is attracted back in the same direction that |
|
| 71:20 | came from. So notice that the gradient and the chemical gradient move in |
|
| 71:25 | directions. So you can use this to determine that point like where is |
|
| 71:31 | point where you, you don't move both directions where everything just stops. |
|
| 71:36 | what nernst equation does here. you have to memorize it now, |
|
| 71:43 | I wanna show it to you for reason only because you guys learned your |
|
| 71:47 | . You guys have walked yourself through two. You'll never use it ever |
|
| 71:53 | , right? The math you should is not CALC three just because you |
|
| 71:57 | take statistics because you'll use that, ? But let me show you something |
|
| 72:02 | . Do you guys remember ratios? ratio right here will tell you if |
|
| 72:08 | number is bigger than that number, you have a number greater than one |
|
| 72:11 | less than one greater? So if number is bigger than that one, |
|
| 72:15 | be less than. So you can this number here. And you |
|
| 72:19 | for example, the natural log of uh a number less than one is |
|
| 72:24 | be positive or negative, negative. negative time to negative plus that will |
|
| 72:30 | you basically the direction in which you're be going and which side of the |
|
| 72:34 | is positive, which side of the is negative. So it becomes a |
|
| 72:37 | tool, not so that you can there and calculate things out. But |
|
| 72:40 | can understand, oh, here's an an ion I've never seen before. |
|
| 72:45 | diffusing across a membrane. Where is equilibrium determined? Oh I can figure |
|
| 72:50 | out. It's when the inside of cell is negative. Oh it's when |
|
| 72:53 | inside of the cell is positive. all you're doing with that. So |
|
| 72:58 | like to throw things at you. like to figure out the math behind |
|
| 73:00 | this stuff. We're not doing math here. Repeat after me, we |
|
| 73:03 | not doing math in here. There go. Thank goodness. And some |
|
| 73:08 | you are like, but I like math. OK, just go play |
|
| 73:11 | that formula. Got a couple of here. We'll see what we can |
|
| 73:16 | through. All right. So as I mentioned, they have no |
|
| 73:20 | or the gates always open is usually you kind of think about it. |
|
| 73:24 | Actually, I I'm wrong. I that back. Poors never have a |
|
| 73:28 | have a gate. They do not a gate. I'll say that |
|
| 73:30 | I was wrong. You can send to my wife. I was |
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| 73:35 | Poors do not have gates. You have gated channels that can be in |
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| 73:40 | open state or closed state when it's its open state. It's considered an |
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| 73:44 | channel. If it's closed, it's to as being gated because you can |
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| 73:48 | and close it. All right. , most channels have these gates stuck |
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| 73:52 | their closed state. So they, basically are spending your time. But |
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| 73:55 | you hear something like a leak we'll use that term that's already has |
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| 73:59 | gate. It's just the gate is open. Hence the leaking. All |
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| 74:04 | , they are selective. Their selectivity based on their structure. So for |
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| 74:09 | , you might have sodium and you have potassium, they both have a |
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| 74:13 | of one. So they're both in same column on the periodic table, |
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| 74:16 | ? Sodium is smaller than potassium, ? Double checking to see. |
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| 74:23 | I think that's correct. All you can have a potassium channel that |
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| 74:27 | allows potassium. It doesn't allow sodium because of the structure of the |
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| 74:32 | You have a sodium channel, it only use sodium. All right, |
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| 74:36 | not because just of the size of molecule it has to do with the |
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| 74:39 | that make up the the channel So it is selective. Here's an |
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| 74:44 | of that carrier that I was showing , right? So you can see |
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| 74:47 | either open on one side or it's on the other side. When you |
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| 74:50 | up, you will be stuck in middle, you're neither open or |
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| 74:54 | This is how you move small organic , things like glucose, right? |
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| 75:00 | that are usually more than an Although we'll see examples when you're moving |
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| 75:04 | ions, you can use a It's a, it's a way to |
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| 75:07 | so. All right, they don't a continuous passage whereas channels create |
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| 75:13 | when they're open, create a continuous . Same way pores are a continuous |
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| 75:17 | that water is allowed to pass All carriers have some degree of |
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| 75:25 | some degree of competition or some degree saturation. And really all that means |
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| 75:28 | specificity means I'm specific to the molecule can carry or the family of molecules |
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| 75:33 | can carry. All right. So example that we can see here of |
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| 75:38 | is glucose and glucose and galactose. you think back to when you learned |
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| 75:43 | these things, you'll remember that they of have very, very similar |
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| 75:46 | It's just a positioning one of hydroxyl on galactose relative to glucose. So |
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| 75:52 | have a molecule that combine glucose very and galactose pretty well as an |
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| 75:58 | All right, because they combine the thing in this particular case, there |
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| 76:04 | be competition for the site if you both of them present. All |
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| 76:09 | I believe that's what the actual thing . Yeah. So here if you |
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| 76:14 | glucose and galactose present, they're basically there fighting over who's gonna bind |
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| 76:17 | It's basically the musical chairs of right, which butt is gonna get |
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| 76:21 | the slot. So competition can The other thing is saturation that's dependent |
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| 76:29 | the number of carriers that are So if I have one door, |
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| 76:34 | , if I have one door, the rate at which you guys can |
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| 76:37 | out of this room dependent upon how people can actually pass through at the |
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| 76:41 | time, but I can increase the by adding another door, right? |
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| 76:47 | , saturation is dependent upon the presence the molecules. How many are present |
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| 76:51 | how many of the car or not the carriers, but how many of |
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| 76:54 | molecules you're actually trying to move? do I have? I got, |
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| 77:04 | , I mentioned active transport. I I can get through this stuff. |
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| 77:08 | don't know, we'll, we'll see if you're just like shut up and |
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| 77:11 | leaving, we'll say we'll go, right, active transport. There are |
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| 77:15 | different types. We've got primary active secondary here. What we're doing is |
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| 77:19 | using energy usually in the form of TP to move a molecule against its |
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| 77:24 | gradient. So when you're talking about here, you have a carrier that |
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| 77:30 | an enzyme site associated with it. A P will bind to it, |
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| 77:34 | will cleave the ATP release energy so it can change its shape. And |
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| 77:38 | you can use the energy from that at P to do the work that |
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| 77:42 | carrier is supposed to do. This the example of what the pump does |
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| 77:47 | active transporter on the other hand doesn't enzymatic activity. Instead, it's relying |
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| 77:52 | the pump activity of that primary active to create a potential energy gradient that |
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| 77:59 | will then take advantage of to move substance against its gradient right now. |
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| 78:07 | that doesn't make it easy to I'm gonna show you some pictures so |
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| 78:11 | you can see this. All So here is the sodium potassium |
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| 78:16 | I'm using a TP, I'm moving from inside the cell to outside the |
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| 78:21 | . I'm moving at the same time outside the cell into the cell. |
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| 78:25 | I'm creating this massive gradient of potassium the inside, massive gradient on sodium |
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| 78:31 | the outside. So have I built potential energy? Sodium wants to go |
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| 78:36 | potassium wants to go out. So I have to do is if sodium |
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| 78:41 | to go in, I can say me create a character carrier that brings |
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| 78:45 | sodium, but at the same time in something else. So I'm using |
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| 78:51 | potential energy of sodium wanting to come to help me transport something into the |
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| 78:57 | . Now I talked really slowly Believe it or not for those to |
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| 79:01 | what? And I usually tell the and I'll have to wait till next |
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| 79:06 | if you want to hear it about to school in New Orleans and about |
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| 79:09 | nights and how it's a perfect example secondary active transport. We'll see if |
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| 79:18 | guys are interested. I'm gonna yeah honestly we're already running out of time |
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| 79:25 | gonna wait. Yeah it is 2 . Ok? So I'm gonna stop |
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| 79:30 | when we come back. I'm gonna to I'm gonna try to summarize this |
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| 79:34 | we move forward, ok? Just that we have some greater clarity. |
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| 79:38 | good. Alright |
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