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BIOL 2301 Human Anatomy & Physiology I - BIOL2301_lecture06_0907
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00:07 Good more. It's always that they better. OK. It's better for
00:16 . Don't like hearing my echo. right. Um So we have a
00:20 next Thursday. Um If you haven't up yet, you don't know how
00:24 sign up. Just remember there's a uh on a canvas over on the
00:28 hand side that says take you to the sign are. Remember also uh
00:35 have exam, have class because you be taking the exam during class time
00:41 that would suck. But anyway, we have that coming up and we
00:46 , that means two more lectures what we're gonna do is we're gonna
00:49 up with the cell. Can believe are still talking about the cell.
00:55 . So uh today, what we're do is we're gonna look at the
00:58 , we're going to be uh talking uh a little bit about the
01:02 Then we're gonna talk about how cells to each other, how they're connected
01:06 so that they can ultimately form right? Because that's ultimately kind of
01:10 we're going tissues and then on and uh we'll finally finish off with a
01:15 bit of mitosis and understanding what that is. But uh there's more explanation
01:20 probably what you need to know. it's not gonna be a particularly hard
01:24 . Maybe if I talk fast, be done early, we'll see.
01:27 know, I saw smiles come up . It was like finally,
01:31 All right. So where we left , we were talking about transporting things
01:35 the membrane. We talked about we talked about carriers, we talked
01:40 and we, we were trying to to here, which is uh vesicular
01:45 . And we were talking about the membrane system and our vestals are
01:49 And uh in essence, what you're is you are bringing materials uh in
01:55 up surface that merging it to the and releasing stuff. And so uh
02:01 we do this, whenever we uh have this sort of movement, we
02:05 refer to it as exocytosis. And this is what this picture is trying
02:09 demonstrate to you. Sorry. All . Um And while these pictures are
02:17 , very simple, they don't show complete process. We talked about motor
02:23 , we talked about how things are along microtubules in a very generic
02:28 saying everything has a direction in where needs to go. So we look
02:31 this, just understand that it's not oh I have a vest, we
02:36 someplace but the materials that we're moving there are not little bitsy bitsy tiny
02:41 . They're not um like little tiny like glucose or like ions like sodium
02:48 . But we're talking about here are that are so big that there's not
02:51 channel big enough to allow them to through or they, you don't have
02:59 car of the membrane. So you something that holds all these large materials
03:07 comes along and then opens up because is, it does require, of
03:19 , I need to press the All right, the opposite of bye
03:32 and back, back dinosaurs. But we start a little bit stand but
03:49 . So over here, we can that there are basically three categories,
03:53 same sort of mechanisms that were involved exocytosis having um a uh a portion
04:00 membrane is gonna be pinched off instead joined up, you're gonna have proteins
04:04 changes which we're not going to talk . But the idea here is also
04:08 to require energy. But what I to point out here is that there
04:12 these categories that separate or make the forms of endocytosis unique. If you
04:18 back and looked at that last picture the lysosome where we were talking about
04:22 , the three ways that the lycos of works. It's like there's fatos
04:27 you can eat a bacteria or you take a destroyed organelle or you're just
04:31 things into the cell. Really? of those are part of exocytosis.
04:38 first one that we have up here called phagocytosis. And this is literally
04:42 cell eating. And so the best to describe this, and I think
04:46 mentioned this to you all. You go on youtube and just look up
04:50 and and uh neutrophil chases bacteria or like that. And so what happens
04:56 that the aha site or faga site is a type of, of immune
05:03 that hunts down large particles that are awesome, come to the surface.
05:20 then what they do is they want cytoplasm and wrap it around the
05:26 So a TP dependent again of Ok. Here on the that I'm
06:01 you is very big, right? something that the wants or needs.
06:16 gonna have a reactor on the surface that then protein structure. And really
06:33 the purpose of it is to take membrane, which looks relatively flat and
06:39 basically bends it so that it starts inward. And so when the protein
06:44 up to the Clarin, the clathrate bending the membrane. And if you
06:48 enough of these receptors that are bound , then you get enough Clarin activated
06:52 you create this uh vesicle that gets from the bending of the plasm
06:58 It's basically an imagination. Now, can't do this with my body real
07:02 because I just don't bend that But you can imagine if it's like
07:05 then what's happening is you're bending downward then it pops up and now you
07:09 a bubble, OK, inside that now is bound up to that
07:14 And then because of the machinery of cell, basically, you separate the
07:18 that you bound up to the you recycle the receptors back up.
07:21 now you have the thing that you and you can do whatever, whatever
07:24 is that you want. So it's very specific mechanism. It's saying if
07:28 want to put this inside the I have the right receptor, I
07:32 up the thing that I want, put it in the, the vesicle
07:36 formed and then I can take that in a TP dependent, but it's
07:42 , very specifically or narrowly focused in you're grabbing. The third type,
07:48 is the middle one. It's called . And it was discovered and named
07:55 because it's similar to phagocytosis in the that you're grabbing something from the
08:01 but it's not quite eating anything. , what you're doing is you're just
08:07 in what's ever in the surrounding So, if receptor mediated cytosis is
08:13 because you have receptors, pinocytosis is specific because you don't have receptors.
08:21 so you get the bending of the , the membrane closes over and now
08:25 captured whatever happens to. So, you were eating mhm This is that
08:36 drinking. All right. So here nonspecific. It's just capturing whatever happens
08:42 be in that material that you're Mhm. So the first time,
08:50 , no. So phagocytosis is not . Remember what I said, you're
08:53 for something. So, it's foreign , bacteria, uh uh large particles
08:59 like DNA damage or not DNA but damaged cell material. So it's
09:04 immune, it primarily with phagocytosis. , it's an immune response. And
09:08 there are two primary proteins or primary that do this. These are called
09:13 . You'll hear about them when we the immune system in the next uh
09:17 in the A P two and neutrophils the other one. Those are the
09:21 big phagocytes in the cell and they roam around your body looking for things
09:26 let's face it. We're clumsy and like to get things in our
09:29 Anyone here live by the five second . You know, the five second
09:33 is you drop something on the pick it up, blow on
09:35 makes it better. Then you eat . All right. If it rolls
09:39 a spider web, blow on it . You're like, man, I
09:43 know about that. Right? No, no, no.
09:48 what doesn't kill you? I wanna you stronger. No, but the
09:51 we can do that for the most is because of an immune system that
09:56 says, oh, that's not supposed be here. I'm gonna kill a
10:00 immune system is gonna be hunting things . So that's what phagocytosis is,
10:05 basically hunting down. Things aren't that supposed to be in your body,
10:08 specific cells are doing. Whereas penoyer that play a role in phagocytosis,
10:14 those are the two big ones. pinocytosis is just general cells everywhere.
10:18 kind of pinch receptor mediated in the . Again, I want this,
10:24 pulling it in. So the only that's really nonspecific there is the pheno
10:32 . All right. So those are different ways we move things across
10:38 including the, the vesicular transport All right, what we're doing is
10:43 still sticking in the physiology mode and , we're moving over the way that
10:47 talk to each other, we call cell signaling. All right. And
10:51 the most part, cell signaling is primarily through chemical messages. So the
10:56 is is that a cell releases a that chemical travels somewhere into the
11:01 whether it's right next to it or long distance away. And then that
11:06 binds to a receptor and activates or the cell. That's that receive that
11:12 , but that's not the only All right. So that's most,
11:16 most common way to do that So through chemical messaging, sometimes we
11:21 what is called electrical messaging and we of confuse this a little bit.
11:26 when we talk about neurons and we talk about electrical and here the
11:34 signal is not jumping from cell to . Right. It's, it's,
11:39 not uh a conductor of electricity. I know this because if I touch
11:44 , you're not going to electrocute me vice versa. Right. Instead what
11:50 signaling is when two cells are touching other and they're allowing ions to pass
11:55 the two cells. And so that's electrical signal, that's a conduction between
11:59 signals. But when we talk about and muscles, which do have a
12:04 use the movement of ions. What doing is you're sending signals long distances
12:10 a single cell. All right. I'm, I'm kind of going off
12:13 a rabbit trail here just to make point. So just bear with me
12:17 a second. But for example, neuron that innervates your big toe so
12:24 you can wiggle, it extends from spinal cord and travels the length uh
12:30 that, from where it exits the cord all the way down your leg
12:33 to your big toe. That's what my body a little bit over 2.5
12:38 3 ft, almost roughly. That's a long distance. That is
12:43 long cell, right? It's a cell, but it's a long
12:49 And so to get the signal from side of the cell to the
12:51 they will use electrical conduction, they'll ions. But that cell at the
12:57 , that's telling that muscle to that's a chemical message. OK.
13:02 the majority of messaging that's taking place through chemical messaging. All right,
13:07 , how we decide which sort of we use is gonna be dependent upon
13:11 whole bunch of things. How close the cells? How fast do you
13:14 to signal something? What is the target of the cell? So there's
13:17 sorts of things. So for me wanting to wiggle my toe requires
13:22 very quick signal. So having long that can communicate quickly across the length
13:27 that cell kind of becomes important, ? But deciding whether or not I'm
13:32 release hormone from my adrenal gland. don't need a very quick signal because
13:37 it will do what I told it do. All right, when someone
13:41 out of the bushes and goes you want your heart rate to go
13:45 and your sympathetic activity go up, want a very quick response. So
13:50 both a combination of, of neural and a combination of hormonal signaling
13:57 or chem. Both of those are of chemical signaling, but you're using
14:00 taking advantage of the neurons to get quick signals moved someplace just as an
14:06 . All right. So what we're do is we're gonna go through and
14:09 the different types of signaling. All , it's easy to say there's cell
14:13 , but you can see why we specific types. All right. So
14:17 first type that I want to mention atoc signaling. Have you ever gone
14:21 the grocery store and made a list yourself? Do you do to do
14:28 ? Ok. Some of you guys do, do, do you have
14:30 tell yourself what to do? Otherwise forget, like I have a list
14:34 things going on in my head right as I'm speaking to you going,
14:38 is my list of things I have do before my next class,
14:41 So this is what autocrine signaling is a cell. It's basically releasing a
14:47 message out into the environment around But that cell itself has the receptors
14:52 bind to that chemical so that the is telling itself what to do auto
14:57 current. So it's basically self All right. So the cell itself
15:02 to have the right receptor. So you can see here's the chemical message
15:06 then you're having the receptor on the and you're getting some sort of
15:09 Now, why, why, why I ever want to do that?
15:12 can I just keep everything on the ? Well, you may be talking
15:16 just to yourself, but you may talking to other cells around you.
15:19 may have a process that's going And so what you're doing is you're
15:23 to create an external signal that comes in and slows down the process or
15:27 on the process. The idea here is I'm telling myself how to respond
15:34 a particular situation. All right, the idea. Just like writing yourself
15:39 note or giving yourself a set of . That's the most basic form of
15:45 signaling. Most of the other type signaling we think about is paracrine
15:51 All right. Now, paracrine signaling signaling to nearby neighbors, not neighbors
15:58 you're touching, but neighbors that are the surrounding area. All right.
16:03 the idea would be, oh, releasing a chemical, it goes out
16:06 the interstitial fluid that that chemical moves from the cell and any cell that
16:12 the right receptor. Notice the characteristic every one of these cases, you
16:16 to have the right receptor. All , when you have the right
16:19 that chemical can bind to it and signal to that cell how to respond
16:23 like an A. All right. here you can see here's our cell
16:28 re released in the chemical notice that a short distance between these cells,
16:32 not next to one another. All , over here, we have cells
16:37 have the right receptors. Over we have cells that don't have the
16:40 receptors, but they're showing you that do have receptors of some type.
16:43 that chemical message binds the cell, right receptor and you get some sort
16:47 response from them. The ones without right receptors basically don't get the
16:52 So they don't do anything All Now, there's a special type of
16:58 signaling that's called synaptic signaling. All . So when we think about neurons
17:03 what neurons do, so this is nervous system works. It will tell
17:08 whether it's another neuron or a muscle a gland or some other cell how
17:13 behave. And what it's doing is we have this long extension of the
17:17 and it comes right up near All right, and it's going to
17:22 its message right onto the cell. we still refer to this as
17:28 OK. So paracrine signaling is simply to a nearby target. All
17:37 now, I'm gonna use that word I don't want you to confuse nearby
17:41 next two. All right, just signaling is a category of para signaling
17:49 is more specific. It is literally cells touching each other in some
17:54 shape or form and the signal is to them. So I would point
17:58 over here in the neuron. Are two cells touching? No. All
18:05 . They are like two siblings in back of a car on a long
18:09 trip. Have you ever played the not touching you game? No,
18:15 , it's a fun game. See this is my little brother. This
18:18 not, I'm not touching you. can't be mad. I'm not touching
18:23 . You see you, you you guys never played that.
18:29 Yeah, this is my side. at me. I'm right on
18:33 I'm not on your side, I'm my side. All right. So
18:37 kind of what's going on? Thank for being a good sport. All
18:42 . So this is what neurons and other cells are doing. They are
18:46 the I not touching again, they not touching each other. They're near
18:49 other over here in Jurin. What the cells doing? What do you
18:54 here? They're touching, what do see here? Touching? So just
19:00 signaling they're touching. Now in the picture up here, the artist did
19:04 really poor job of the, the you. All right. Here,
19:08 two cells are actually in contact with other. But what they're trying to
19:12 in the in the picture is they're to show you the interaction between a
19:17 on one cell and a receptor on other cell. So here what we
19:21 in, in this upper this direct is that we have two cells that
19:26 come into contact with each other. the way that they're communicating is one
19:31 a thing that can be recognized and has a recognizer, right? The
19:36 is a recognizer. This is how lot, a lot of immune cells
19:40 to each other, they're circulating through body, they come into contact with
19:45 other. They use that receptor ligand and they tell each other what to
19:51 if you're paying attention during COVID. said one of the things that they're
19:55 for, the thing that's so dangerous COVID is something called a pine
20:00 Do you remember hearing that? ok. Well, that was the
20:05 deal. All right. That's why is so concerned because it was taking
20:09 immune system making it go all whack do. All right. So,
20:13 of the ways, so the cytokines the way that cells uh communicate with
20:19 other. And there are hundreds of cytokines. It's, it's ridiculous.
20:23 of them are released out into the , but some of them serve on
20:27 surface just like you're seeing. And is how one what when you have
20:36 activated T cell says, hey, , I've discovered something, something
20:41 Let's go wake up the rest of immune system and goes and tells the
20:43 cell and says, here we hey, guess what I found and
20:47 activates the next T cell. Next you have is an army full of
20:50 cells hunting down all the bad things your body. Well, the one
20:53 thing in your body, but we'll get there later. All
20:56 So this would be the direct Another type is a type of contact
21:02 through the cell adhesion molecules. These called cans and cell adhesion molecules simply
21:08 the molecular velcro that hold cells All right. So we have two
21:12 . One has the ligand one has receptor, they basically bind each
21:15 they hold on to each other. now we have contact signaling here.
21:20 , for example, when you get cut, if you were to cut
21:24 , do you get like the wound of heals itself? Right? The
21:27 kind of grows back into place. . I mean, some people are
21:31 there to, for the rest of haven't got go outside, play a
21:35 football, you know, do something , get a scrape and see what
21:40 . All right. And you'll see skin grows back for the most
21:45 And the reason it grows back is when they're touching each other, they
21:50 signaling and telling each other don't grow . But when you separate them
21:55 then nothing's telling you don't grow. so they grow until they touch and
21:59 a result of cell adhesion molecules. right. The other type of juri
22:05 is where you would see electrical All right. So here what we
22:10 is we have a cell attached to cell via a series of specialized junctions
22:16 gap junctions. It creates a gap the two cells. And so if
22:21 have ions over here, they can over over to there if there's a
22:25 gradient and vice versa. And so the way that I can create current
22:30 cell to cell to cell. This how your heart works, right?
22:34 have specific cells in our heart that call pacemaker cells and they create an
22:39 potential. In other words, an potential, an ion gradient change.
22:44 so how that action potential moves from to cell. The cell is through
22:48 gap junctions. It takes, it in one cell gets passed on to
22:52 next cell gets passed on the next and so on and so on and
22:54 on. And that causes a contraction those muscle cells. Again, more
23:01 , a little bit later. But idea here is a gap junction allows
23:05 materials to pass between two cells as form of signaling. And I think
23:10 have listed up here a couple of different things that can serve as signaling
23:15 . We don't usually think about a as a signaling molecule, but it
23:18 serve as a signaling molecule. It's amino acids can be changed, small
23:25 messages can be used as a mechanism communication. So, so far talking
23:33 myself, talk to the neighbor, the person or the cell that I'm
23:38 to. Those are the three right? So pretty straightforward. And
23:43 last one is one where, where , when we think about cell
23:46 this is what we think about is signaling or long distance signaling. So
23:51 what we're doing is we're have some of cell that's producing a chemical
23:55 that chemical message gets released from the and it goes into the bloodstream and
24:00 some distance away, how far, . So it could be literally from
24:08 part of the brain to the So we have the hypothalamus, for
24:12 , in the, in the pituitary , which are separated by about two
24:16 of tissue. And there is a system between the two and so we
24:20 signal from the hypothalamus to the pituitary or what we can do is we
24:24 signal from the gland all the way to the adrenal glands or the gonads
24:29 the stomach or whatever other type of uh structure you have in the
24:33 The idea here though is that the molecule goes into the bloodstream and then
24:39 to another part of the body to on that other part of the
24:44 All right, again, the same apply. You have to have the
24:49 receptor. If you don't have the receptor, the cells just ignore because
24:54 can't bind to that signal. Um type of signaling, this endocrine signaling
25:02 what we refer to as the signaling as is a hormone. So when
25:06 hear hormone, think endocrine signaling, , ma'am. Yes. So this
25:17 a form of chemical signaling. So one of these that we looked at
25:21 a form of chemical signal, electrical . We could see with the gap
25:27 and I was giving an example through the heart. But everything we just
25:31 at here is all about chemicals. so we notice we're not defining what
25:35 chemical is. We're just saying it's chemical. So it can be,
25:40 gonna see here in just a It could be like a steroid,
25:43 could be a peptide, it could a protein, it can be
25:48 These are all different forms of chemicals can be used as signaling molecules.
25:52 in this case up here, uh regard to Iran, we have basically
25:58 types. Well, there's a third um form from amino acid, but
26:03 peptides, steroids or amino acids. this is simply how body tells other
26:10 of the body how to behave. again, generally speaking, when you're
26:15 about this type of signal, when talking about chemicals, you're talking about
26:18 slow response. When I say that's a relative term. All
26:24 So for example, a neuron fires , in terms of milliseconds,
26:30 That's, that's fast, right? hormone responds within minutes to hours and
26:38 like steroid hormones respond like in So milliseconds versus days, you could
26:47 the difference between fast and slow, ? But I'll just give you an
26:52 . Again, this is uh some the graduate work or postgraduate work I
26:56 doing was on a hormone uh that's for uh ovulation. And so the
27:04 that I would do I would inject with a hormone and as soon as
27:09 injected all my plates and they were 12 plates. It would take me
27:13 15 seconds to do that. And that first plate I would take,
27:17 I'd freeze it immediately to stop the . So I was trying to find
27:23 in 15 seconds. Do I get response? And then I had a
27:26 , then a minute, then a minute, a four minute a or
27:30 a five minute, 10 minute, minute hour, two hours,
27:34 I can't remember. I went all way up to 48 hours, but
27:37 was the idea. And so I look and see what happened at this
27:41 here and I could see a peak then it would come back down
27:44 And I was just looking for that gives you the sense of uh
27:48 early as a couple of seconds. right. Now, when we talk
27:57 this type of signaling I have up , it's part of the nervous system
28:00 part of the endocrine system. All . So hormones can be produced by
28:06 uh the nervous system. And so I describe the hypothalamus, for
28:11 that's part of the nervous system. anterior pituitary and the posterior pitu are
28:15 of the nervous system. Ok. so when they produce hormones, we
28:19 them a special name, we call neuro hormones. And all we're doing
28:23 we're just defining where they came but most of the organs in your
28:27 have an endocrine function. When we about the endocrine system, we think
28:31 those we might think of the adrenal . We'll probably think of the gonads
28:35 endocrine, but your stomach is an organ. It produces hormones to tell
28:43 small intestine what to do as an . All right. So there are
28:50 types of endocrine organs. Some of are specifically endocrine in nature. Some
28:55 them have dual functionality. And just show you it's not just think of
29:00 gonads, your gonads produced gas that used to reproduce, but they also
29:07 hormones which serve in the process of . It kind of makes sense.
29:14 . All right. You don't want talk about your sex organs. Fine
29:19 . Go nets. Yeah. it gets fun, more fun.
29:24 wait, we'll have lots of Think of the kidneys. What do
29:27 think about? What do the kidneys ? For the most part? It
29:31 blood, right? It's it basically the waste. Yeah. But it
29:35 plays a major role in managing blood through endocrine signaling. OK. What's
29:46 right. Do do these different things sense so far? The different forms
29:53 signaling, near signaling, self next to signaling, far signaling.
30:00 all we just did gave him special . The thing is where there are
30:07 types of signaling molecules. As I , we have molecules that are like
30:13 and molecules that are lipid, these , for example. And so these
30:19 have very specific characteristics. So for , a peptide is water soluble,
30:25 means it can't pass through a So in order for it to
30:29 it has to act through a receptor the surface of the cell. And
30:33 it uses a signaling uh process like is what we refer to as being
30:38 metabotropic. All right. And where scary word comes from, the first
30:43 is from metabolism. So something is processed and then the tropic means to
30:49 . All right. So it's activating a metabolic process. All right.
30:55 so what we can see here in , in a very generic way and
31:00 just gonna tell you right now, are at least 5000 that do
31:08 It's probably closer to 10,000, but being conservative. All right. So
31:12 you learn how it works in a way, when someone introduces you to
31:16 process, you'll be like, oh this makes starting to learn this
31:22 All right. So for example, is how insulin work just as an
31:27 . All right. So here you a receptor, you have your signaling
31:31 , we call that the ligand, ligand binds to the receptor and that
31:35 of the lion to the receptor changes shape of the receptor and that is
31:39 activation event. And so when I that protein, it activates another
31:45 which it another protein, which is protein. How many proteins are in
31:49 chain? Who knows? It could one, it could be 20.
31:53 right. But the idea is that turning an outside signal here into an
31:59 signal here that change of outside to is transduction, right? And transforming
32:07 outside to an inside down at the end is where you're gonna get the
32:17 . All right, the response is change as a result of that signal
32:24 here. Now, within the transduction , we're gonna get two things we're
32:31 get in all likelihood, something that's a second messenger. If something in
32:38 is the second messenger, what do think we call that one? The
32:42 messenger? See it's not rocket it's biology, right? It's
32:49 We, we are not interesting. message through the receptor, get a
32:53 message. Then the second message ultimately or, or inactivates another molecule downstream
33:00 creates response. It creates an effect the cell. So we refer to
33:05 target molecule down at the bottom end this pathway as the effector because it
33:14 the effect. All right. that's a very generic way to look
33:21 one of these pathways. All And there, as I said,
33:24 are thousands of them in your nose . The your ability to smell different
33:31 is a function of the 4000 different of receptors that are in your
33:37 They're all of the same type, all behave the same, but they
33:45 a different protein. So the cellular can be an activation or inactivation.
33:51 we can either turn things on or that are already there or what we
33:56 do is we can turn on or off genes. Now, to understand
34:01 , when I came in the room morning, this room was dark.
34:04 did I do to make the room ? I turn on the lights.
34:08 already in the room, there is switch, there are wires that go
34:12 to the lights, the lights already in the room. And so all
34:15 got to do is push a So what I'm doing is I'm creating
34:18 cascade of events to create light to in the room, right? Everything
34:24 already there. So that would be example of this first step. All
34:27 , we're changing the activity of what's on in the room, the lights
34:31 off. Now we turn them on regard to this latter one. When
34:35 dealing with gene expression, there are lights in the room, there is
34:39 switch and there are no wires to lights. So what we're doing when
34:43 doing gene expression is we're turning on to make the lights, to make
34:49 wires and to make the switches so everything turns on which you think takes
34:55 . The second one, the gene one All right. So you can
34:59 now where we have a timing but notice I can do one of
35:03 things here, either I have things place like you see here. And
35:07 the response will be there's stuff down that I'm turning on or I can
35:11 this and it goes and acts to on genes. This is just another
35:18 of this. So you can see these cascades kind of work. And
35:22 , this is a simplified example. again, rightly, so the idea
35:26 here is my ligo there is my . I turn on a protein which
35:29 on another one which turns on another which turns on another one which turns
35:32 another one which gets our response. you see that little p there,
35:36 a phosphorylation event. All right. with phosphorylation, that is a way
35:41 we can turn on or turn off protein. And again, it's depending
35:45 what you're looking at, we usually think phosphorylation equals activation. And that's
35:50 enough for right now. But noticed got all these different steps. You're
35:55 here wondering why do you have to all these different strips? Why do
35:58 have to have a cascade? Because protein right here doesn't just turn that
36:05 on, there might be four other . So you're turning on one that
36:10 on mini and each of those turn many, which turns on many and
36:14 instead of having all these different you have one switch that turns on
36:19 things. And so you get a response, which is why hormones are
36:27 , really highly, highly regulated. right, you can use one molecule
36:36 get a massive response because each of are amplifying those signal, not just
36:42 spreading it outward, but because they these things active for long periods of
36:47 . And again, that's a relative . So you get these massive responses
36:51 a result and what this is just to show you is a process that's
36:55 on. Now, every one of things are going to be highly
37:03 So like we're going from here to and it's showing you here I'm
37:06 But the truth is, is that going to have for everything that I
37:12 , I have to have some sort mechanism to inactivate it. All
37:16 The idea here is I, a should be something that's quick that gets
37:20 response. And then we, we're with the response, right? It's
37:25 when you walk into a room on light, when you leave the
37:28 you turn off the light, only person said that in Paris, when
37:35 walk in the room, I turn the light. When I walk out
37:37 the room, I off the you'll become more familiar with this process
37:42 you have to start paying electrical right? Every morning my kids leave
37:47 school before I do. I walk and I go through each of their
37:51 to turn off the light because I how much it costs. Right.
37:57 that's kind of what's going on I don't want the cell to keep
38:00 the same thing because that cause me an organism harm. So each cell
38:06 does the one thing and then it a mechanism to turn it back
38:10 So there's a regulation that is taking . Now, this is not anything
38:15 you have to memorize here. It's understand if I turn something on,
38:19 a switch right there to turn it back off again. So when I'm
38:23 at this cascade, it's showing me turning all these things off. What
38:26 we not seeing all the signals that turning it back to the original inactivated
38:34 ? So a signal is a brief that's taking place and again, brief
38:39 a loaded word. It could be couple of minutes, it could be
38:42 hour, it could be a couple days, whatever, but it's not
38:45 to be permanent. Another type of is this right here, ionotropic.
38:53 metabotropic means using um a metabolism to to activate something, what do you
38:59 ionotropic means using an ion? And so here what we're looking at
39:05 we're looking at a channel, you can see the channel up there,
39:08 little red Pentagon looking things, the things that look like houses and
39:14 Oh my top is shut, pour tea down my nose. All
39:21 . Those are representing the lions. when that ligand binds to that
39:25 it causes a channel to open. the key to the channel. So
39:29 the channel opens up, that allows to flow down its concentration creating into
39:33 cell, this is creating a So when I create currents, I'm
39:39 electrical activity, this is how neurons the most part work. Now,
39:43 work is basically I'm opening channels. allowing ions to flow through when the
39:48 flow through the cell becomes activated. it creates an electrical signal that travels
39:54 the cell for something to happen. now, when this opens, it's
40:05 quick open and close, open close it up. It's like this
40:09 . If I went and opened this pressed on it, it has a
40:12 or a, a an arm on that basically says when it's open,
40:16 back to the closed state. And that's kind of what this does.
40:19 quick open and it slams shut. again, you're gonna get a very
40:22 signal. These are gonna be the signals in the body, the last
40:29 of signaling or uh how we produce the nuclear receptor. Now, this
40:37 is appropriately named, but it can confusing because nuclear receptors are not just
40:42 in the nucleus. That's just where act when they're unbound. They can
40:47 in the nucleus and they can exist the cytoplasm. They're just waiting to
40:52 bound up. Now, peptides we cannot penetrate through the plastic membrane because
40:58 lipid or sorry, they're water They love the water. They don't
41:02 fat. Steroids are a form of . They love fats. They don't
41:09 being in water environments. And so they're doing is they can, when
41:13 come along, they're like, ah don't like being out here. So
41:16 can zip into the membrane as quickly they can. And then there are
41:19 that grab them and covered you and what they'll do is they'll carry them
41:23 the nuclear receptors and give them to nuclear receptor. The nuclear receptor once
41:29 says, oh I'm not supposed to out here in the cytoplasm. My
41:33 is to be in the nucleus and it will translocated into the nucleus with
41:38 ligand, with that steroid attached to . And the way that it works
41:42 that basically you need to have two these receptors bound and they come in
41:46 they bind to DNA and they act a transcription factor. So the only
41:51 they work is through that second we describe creating genes so that we
41:57 create new proteins so that the cell behave in a different manner. So
42:03 way the steroids act is rather slow to metro and very slow relative to
42:12 , right. So the fastest is . The second fastest metabotropic right,
42:21 through those cascades. And the third be nuclear receptors because they only do
42:26 expression or gene uh protein or DeNovo synthesis. But gene expression is fine
42:33 metabotropic that does gene expression. Those are kind of equivalents. So do
42:40 pathways kind of make sense in terms what they're doing. I'm not gonna
42:45 you what an hr e is it a hormone response element just tells you
42:49 a hormone binds with its receptor. Yes. The true the legend
42:59 What part of this? Right? the question is a ligand,
43:05 So a ligand by definition is any that is capable of binding a
43:11 OK. So notice we didn't define the molecule is for the most part
43:16 are peptides, but they're not only . OK. So just when you
43:23 the word ligand, something that binds a receptor. OK. So in
43:30 case, sorry, here we This is a steroid. Is the
43:35 here a ligand? Yes or What do you think? Yes,
43:40 it did what bound to a All right. It's just a word
43:45 help us understand what its function is . All right. Now, even
43:56 we have this delay in this response it takes us so much time and
44:01 have these genes being made and you're these molecules in the RN A and
44:05 sticking around for a long time. response you get are long lived.
44:10 extend for long periods of time. . Remember as I'm turning things
44:15 I'm immediately things here, there's nothing , once I'm making the proteins,
44:22 gonna stick around for some period of . And that's why they're long,
44:30 ? Questions about any of this that talked so far. Yeah.
44:38 Long distance, right? And that's for any form of signaling,
44:47 If, if let's pretend for a that we follow the rules and if
44:53 receive a letter that is not addressed me, am I allowed to open
44:58 ? No. So that message whatever is is not for me, it
45:02 be congratulations. You have won the and such. It's not me.
45:06 don't get the message so I don't to do it. So the message
45:09 to be addressed to me and that's what the receptor is there for.
45:12 if you have the right receptor, can respond at any distance,
45:18 So one of the things that becomes important and this is just an aside
45:23 at if, if a, if molecule can activate another cell at any
45:28 because it has the right receptor and don't want to activate cells at any
45:33 , you only want to activate nearby . So one of the things you
45:36 to do is you have to regulate long that ligand stays around. And
45:42 there are enzymes in your body that literally chewing things up almost as immediately
45:47 it's being produced. Right? So with regard to, sorry,
45:57 the question you're asking is again, yes. So, so what's happening
46:05 ? So I think what you're asking when this, when this receptor gets
46:11 , we're getting a change inside the , right? Or is it just
46:14 general? Generally you're asking the Yeah. So the question is is
46:19 a ligand binds a receptor, you're get some change in the cell.
46:22 , that's always gonna be the What that change is depended upon signal
46:27 what the receptor is and what the that is involved in. All
46:30 And that's beyond what we have to ourselves with today. But you just
46:34 to think is I'm telling you if , we're in class and I give
46:38 a note and that note says, don't know, we're, we're messing
46:42 the teacher today. So you're gonna making little whooping noises quietly through the
46:47 of your mouth. Yeah. So changing the environment, right? That's
46:52 idea just like that. OK. good with the physiology for right
46:59 We're ready to go back to some kind of, it's kind of
47:03 All right. So what we've been is we're trying to set up the
47:07 to understand how tissues and organs That's where all this stuff is.
47:10 , if you're sitting there going, don't understand why I have to know
47:13 . That, yeah. Oh, . Because have been giving you little
47:17 a little taste here and there and we're doing now, we're going to
47:20 the questions. All right. cells talk to each other because they're
47:24 tissues and they have to talk to tissues. They also form tissues and
47:28 way they do so is through different , types of junctions. All
47:34 And again, when I sat in seats, there was tight junctions,
47:37 junctions, hemi desmond zones, and zones. And now there's adherence junctions
47:43 even looking, what do you think adherence junction does? What do you
47:46 it does it had here? See . Yeah, you're, you're
47:51 All right. What do you think tight junction is? It's tight,
47:57 ? Desma zones? Oh Man, weirder. OK. So what we're
48:01 do is we're just gonna kind of through and ask these simple questions.
48:03 right. What, what do these do? And we're gonna see that
48:07 is some similarity but the differences happen be in what proteins are available.
48:11 right. And so some else is . So for example, and vice
48:17 . But what a desmosome is, basically holds two cells together. And
48:21 can see in our little picture this is cell number one cell number
48:26 . And this is the attachment that would call a desmosome and we just
48:30 it out so that we can look there. And so you can see
48:33 have a series of, of uh adhesion molecules. These are called cad
48:38 , all right. And so these penetrate through the plasma and bring to
48:43 other side. And then there's this work of protein that creates what we
48:49 a plaque, right? So like plaque on your teeth, it's like
48:53 , except it's not plaque on your . It's just a structure that's kind
48:57 uh holding things together. And then from that are a series of intermediate
49:02 that travel throughout the cell and then to another plaque which has another uh
49:07 series of cams underneath it and then cams in those two cells. So
49:12 have CAMS on this side, cams that side, they recognize each other
49:15 they are holding on to each And then again, on the
49:18 you have the plaque and you have intermediate filaments. And so what this
49:22 is allow cells to attach each other distribute tension between the cells. And
49:27 is that example of that Indian We're describing the reason that your skin
49:31 come peeling off is because when I on one cell, I'm not only
49:35 on that one point, distributing the across the entire cell and then being
49:42 to next cells next to it. then that tension is being distributed to
49:47 cells and onward and onward and onward onward. And this provides strength to
49:52 tissue that we're looking at. Right. Now, the desmosome is
49:58 parts. So half of it belongs one cell, half of it belongs
50:01 the other. And the stability that provides ensures that the tissue is
50:10 This is a terrible picture trying to you this. It's trying to kind
50:14 point out it says, look you can see the desmosome cells are
50:18 like this. They don't have these gaps like this. All right,
50:21 literally next to each other. But trying to show you you can see
50:24 the intermediate filaments that would be the at each of those points. But
50:29 thought this was a good way to look and focus in where the desmosome
50:33 and how each cell is connected to the other cells in that tissue.
50:40 also have half desmosome or hemi desmosome the correct term. And so here
50:46 can see the cell here, you see its plaque here. You see
50:50 uh cams here, you see the filaments. But on the other
50:55 we don't have that. This is cells attach themselves to the underlying connective
51:02 . They use the matrix of the tissue to make the connections with those
51:08 cell adhesion molecules of the half And so again, your skin doesn't
51:16 off, even though it's not connected cells, it's connected to a layer
51:20 connective tissue because of this type of . And again, this is going
51:25 way more detail than you need to . Right. It's, we,
51:29 not concerned which are the molecules The idea is, it's like a
51:34 , it's just half of one and the connective tissue, you're using proteins
51:38 its matrix to attach yourself to. the adherence junction is like a desma
51:50 . All right, we don't have plaque, all right. But we
51:55 have proteins that are holding things in . It creates something that is less
52:01 than the intermediate filaments. But we're ain instead of the intermediate filaments,
52:07 we still have adhesion molecules and we a network that basically distributes force along
52:15 cells. All right. So adherence are like desmosome. They use acting
52:22 of intermediate filaments. That's the key I want you to take away.
52:27 right. In the last uh not last second, the last I think
52:34 junctions, they tell you what they , they're, they're tight, uh
52:38 have a protein in them. It's ACLU. So these little things they
52:43 it includes, right? So the you can think about this is here's
52:47 number one, cell number two. you ever worked with the Ziploc
52:52 Right? You zip it and now can't go into the Ziploc bag.
52:57 kind of what these molecules do. basically says here's two cells and I'm
53:02 block the interaction between the two the in between them. So I can't
53:08 material where these eluent are located. if I had material floating in
53:16 it would come here and I can't . So I'm stuck on this
53:19 If I'm on this side, I'm on that side. The better example
53:23 this is here, you can see is an example of epithelium, say
53:29 the gut, right? And so would be inside the gut. So
53:34 your lumen. This would be the tissue and the basal lateral side.
53:39 you can see type junction, tight , I cannot pass in between the
53:44 . If I have material, it to pass through the cell. If
53:48 don't have a tight junction path of resistance, I'm gonna go in
53:54 All right. Now, generally when you have tight junctions, they
53:57 truly tight, they will not allow you have to go through the cells
54:01 that you can regulate what's passing. there are parts of the body that
54:04 the best oxymoron in biology. The T junction, leaky type junction,
54:13 a wonderful oxymoron, you're leaky, you're tight. So, right,
54:21 . All right. Now what this because these are proteins and, and
54:25 just gonna highlight this because I think is really kind of interesting because it
54:29 become important when we deal with you see kind of the pinkish rose
54:33 here that's coming along along the, that edge. Do you see
54:39 So what you tied up here and side down here, this rose colored
54:47 represents not only where the eludes but the network of proteins that are
54:53 to the eludes. And so what end up doing on the inside of
54:57 cell is you create a pole. you create one side that's different from
55:02 other side. And so one of ways that the cell knows which way
55:06 send materials is because of this polarity the cell, right? So it
55:12 which way is up and it knows way is down. So you're not
55:15 enzymes out only into the lumen or only secreting into the lumen, you're
55:19 going to secrete enzymes that can destroy body through the basal lateral side as
55:24 example. All right. So the junctions don't just sit there and create
55:30 barrier from the, from the It also creates this unique barrier on
55:35 inside to help the cell know which is up and which way is
55:41 which is kind of cool. All . So that's the directional movement.
55:48 what it allows it to do. already talked about the gap junction just
55:54 , but I'm just coming back to . So here the gap junction is
55:58 how we allow two cells to send between them. So remember, it's
56:02 form of Jurin signaling here. So is formed by a series of proteins
56:08 connections. So you can see here have connections on one side, you
56:12 connections on the other side. This creates a channel that can open and
56:17 . So you can actually decide when are going to pass through. So
56:20 is just trying to show you, look, these three cells are talking
56:22 each other and what it allows to through is dependent upon what sort of
56:27 you're located in. So like I , when you're talking about heart
56:31 for example, these types of gap allow for ions to pass through the
56:35 thing with smooth muscles, but other may pass other materials through them.
56:40 we share materials, cells are connected each other in a variety of different
56:51 that allows them to communicate, allows to interact, allows them to create
56:55 networks. And one of the things want you to take away here is
57:01 the outside of the cell isn't some of smooth, simple structure.
57:06 there's lipids, there's proteins, but more to it than that. There's
57:10 matrix of proteins that sit outside all cells that we refer to as the
57:17 matrix. So here you can see cytoskeleton, there's your plasm membrane
57:21 you can see the trans membrane you can see some more glyco
57:27 those glycoprotein collectively are referred to as glycolic. We talked about that.
57:34 outside the cell, we have other molecules that interact and create this matrix
57:40 serve as a protective barrier that serve a binding signaling environment. It has
57:49 these different types of roles um that for unique interactions to take place externally
58:01 . So it's not these bald cells are basically here's a receptor so on
58:06 so forth, it's far more So I'm just kind of trying to
58:10 here, we got collagen, laminin. These are long chain
58:15 We have proteoglycan, which is just stupid word that says proteins, sugars
58:20 proteoglycan have sugary proteins on them. the silly silliest thing. All
58:28 But the proteoglycan are the things that water in your cells. And
58:33 and when I put water in your , I'm creating an environment for chemical
58:49 . Now, we get to the of biology that you've already learned.
58:51 there any questions about the uh types attachments, the types of junctions you
58:59 him should be straight forward again. just introducing these ideas. So as
59:04 come along again in the future and start talking about it, you're
59:07 I have this, I've never seen before in my life. That's why
59:11 do that. And I would add I'm as I'm kind of coming
59:14 How many more slides do I Like four, three? See I
59:18 you, I told you if I fast quick now I can go tell
59:22 stories about my past. You're no, get it done.
59:28 All right. Um So we have more slides. Um What I want
59:35 tell you is, uh just before came to class, I, I
59:38 every year I post on uh, , it used to be blackboard,
59:43 I used to post a video called , the Life of The Cell.
59:46 on youtube. So I put on module for this unit, a link
59:51 that video. If you wanna watch , it's an eight minute video.
59:54 doesn't have narration or anything, you watch it and it's just a digital
59:59 of all the things that we've talked and it, and it'll show you
60:03 and it'll show you stuff that we seen, like it'll name proteins and
60:06 like, I don't know what that . Don't worry about that. But
60:08 you want to see kind of this representation of the we've seen and to
60:14 this is a good thing to watch if the eight minutes is too
60:17 just go on youtube type in life the cell. There's a truncated three
60:21 video of this where that what or it was, it's a Harvard digital
60:30 , but it's really kind of So the last thing here is I
60:34 to talk about cell cycle. One the things that we said that living
60:37 do is they reproduce. All So they have a life cycle in
60:42 , that's what the cell cycle It describes kind of the long life
60:46 that a cell goes as you've learned before. There's two primary reason uh
60:52 uh periods in which a cell Something that's called the interphase. The
60:58 is what cells are basically doing. they're just like when I'm functioning and
61:02 being a normal cell, I'm existing interface. But when it's time for
61:07 cell to reproduce, they enter into mitosis is the process of nuclear and
61:15 division. And it has two we call mitotic stages. That's prophase
61:21 phase, anaphase heal phase. You remember learning that OK, we're gonna
61:25 , we're gonna briefly just cover And then the other half of that
61:28 the, the body, the, cell itself breaking apart, which is
61:33 . All right. So that's the division. And so this, this
61:36 cycle right here is being, is shown here. Um So what I
61:40 do is I just want to focus , very briefly on what interface
61:43 All right, understanding that you might one question on this. It's not
61:50 memorize this. Know every part of . If you're a biology major,
61:55 will get this plenty of times if just planning on nursing school, understanding
61:59 cells go through a stage of activity then division, you're probably fine for
62:05 . It, well, it's I mean, a lot of the
62:07 they teach you you'll never use ever . All right. That's, that's
62:12 . Although it's probably helpful to know . So for example, for people
62:16 gout, they give them a medicine culture. And what culture is seen
62:22 it's, it's a chemical that they from crocus, that's a flower and
62:26 halts mitosis in all the cells in body. So basically, it's a
62:32 , but it's more deadly to the that cause the gout than the your
62:38 body. So it's kind of that of let's give you just enough
62:41 not to kill you, you but to deal with the process.
62:45 understanding that, oh it affects mitosis now you know what it does,
62:49 ? Prevents cells from dividing. All . So here we got, we
62:53 three sub phases. We have the one, the G two and the
62:56 the G one is basically cell is through a division and now it's kind
63:00 ramping itself up to do its right? And so it may be
63:05 kind of going along and doing its if it's, if, if that
63:08 basically says I'm going to do this for the rest of my life and
63:12 not going to divide ever again. basically your G, one becomes a
63:15 zero or G not. And so you're done, you're just kind of
63:19 , this is what I do this is, this is my
63:23 But let's say you're a cell that destined to divide again. And so
63:27 will happen as you're going along, enter into the S phase. S
63:32 is the DNA synthesis phase. So I can replicate, I have to
63:36 my DNA. And so that's what S phase is for. It's
63:39 oh, it's time to get ready division. And so what I will
63:44 is I will go through and I'll all my DNA. And then before
63:48 enter into mitosis, I have to check to make sure that I did
63:52 work correctly because it's not always And so the S phase is
63:57 is the replication phase and then the two is the, let's check our
64:03 . You were taught to check your , right? That's kind of what
64:07 doing here. All right, you're your work. All right. So
64:12 stands for growth or gap, whichever you want to go. So that's
64:16 easy way to think about this. is me doing normal things. This
64:20 me replicating my DNA. This is prepping and there are processes that are
64:28 into the next stage. So there stop and start points along the way
64:36 it comes to mitosis. I kind laugh when I look at this because
64:41 far more complex than what we teach guys. There's like five stages of
64:45 phase. You know, we're not ever do any of that. All
64:49 . But the idea here and I'm not going to throw a picture
64:51 here and say, tell me what is. The idea here is,
64:54 , during mitosis, I've now doubled DNA and I've got to split this
64:59 to two daughter cells that are exactly . So, what I'm gonna do
65:03 I'm going to go process of condensing DNA down. So it's manageable.
65:08 gonna get rid of that nucleus so there's nothing impeding me from dividing up
65:13 DNA. And then I'm gonna use the centris and I'm going to use
65:19 filaments to take that DNA and separate out. So, before I separate
65:24 , I got to line it up the center and I send out these
65:27 filaments, I attach them to the part, the dots go to the
65:34 side and then once each side gets uh nuclear material, then I'm gonna
65:39 that nuclear material in a new And then by the way, I
65:42 to now split the cell. So kind of equally divided the, the
65:46 and stuff between those two things. I begin uh separating the two halves
65:51 a process of cytokinesis. All And that's what occurs, prophase beta
65:57 . And a phase hese. I'm interested in you memorizing every single stage
66:03 . That's for biology students. But I want you to understand that
66:09 is an ordered um um process that going through step by step. And
66:15 there's a mistake, if something goes off with their heads, this whole
66:22 stops and the cells are removed. . So are you saying we don't
66:27 to know what each day? I'm particularly concerned about that. And if
66:32 some magical reason, I put all different things, like ask you a
66:35 , what is a meta phase or pro phase? Send me an email
66:39 say you told me I didn't need know this and I went fine and
66:43 give points back because that's just what do. All right. All
66:47 I'm just double checking. Oh, , there it is. So this
66:50 cytokinesis. And again, what is trying to demonstrate to you cytokinesis?
66:55 is the clear thing. So, is a broader process of nuclear
67:01 cytokinesis. It's a separation. Understand that those definitions are unique and
67:14 process of mitotic phase refers to both them. We have one more lecture
67:20 Tuesday and we have a test. right, I will see you on
67:24 . Have a great weekend.
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