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BIOL 2301 Human Anatomy & Physiology I - 2301_lecture06_0908
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00:07 All right, here we are, morning, it was harder today,
00:11 it good enough? It felt like I was it was dark, it's
00:17 get worse, just let you it's gonna get worse always towards december
00:22 , especially if you're not a morning , anyone here, not a morning
00:26 , I'm not a morning person. I didn't have to teach this
00:29 I wouldn't get up till like So today, what we're gonna
00:33 we have three things we're gonna Uh we're gonna talk about cell
00:36 Um and the good news with when talk about cell signaling, what we're
00:40 is we're keeping it very general, basic. Alright, we're not gonna
00:44 asking specific pathways or anything like so that's good news. Second thing
00:49 gonna talk about is we're gonna look how cells are connected to each
00:52 So we're gonna look at these different of connections and the last thing we're
00:55 is we're gonna do look at cell , Right? So that word,
01:01 replication should kind of key in on , is like, oh, that's
01:04 of the things that living things do replicate themselves. So, we're gonna
01:08 at that cell cycle and ask that , what are the steps? You've
01:11 already seen this stuff before. I that part, because that's just
01:16 And when I say that word, of you cringe somebody go,
01:19 I've heard of that. All and so today it shouldn't be particularly
01:23 . And when I looked at like, well, get out
01:25 but once I say that that means going like right to the very last
01:28 . So, you know, if start telling stories, just say shut
01:31 . Alright, that's easy. So cell signaling is simply the way
01:35 cells talk to each other. If each cell is a compartment where
01:39 chemical reactions are taking place and I something that I need to make another
01:44 do I need to send a signal that cell? All right. And
01:48 I've got cells that are nearby you know? So they're nearby.
01:52 might even be connected to me. then we have cells that are very
01:55 away that I need to talk Alright, So there are different mechanisms
01:59 are being used to allow this to . We have different names for those
02:03 . So, the large picture the grand picture of cell signaling is
02:07 of just summarized up here, There are lots of different ways that
02:10 do this. It all depends on proximity, it depends on how fast
02:15 need the speed to be. And , what is your intended target.
02:19 , that's how we decide or which is going to be used.
02:23 Typically, what we're going to see that most stuff like 95, maybe
02:29 percent of the signal that occurs in body is going to be through chemical
02:33 . Alright. But then when we talking about neurons, we're gonna start
02:36 about electrical stuff. But understand that we're talking about electrical signaling, electrical
02:42 as referred here refers to two cells contact with each other. That allow
02:49 uh ions to pass between. So other words, the electrical signal passes
02:54 cell to cell to cell to When we talk about neurons, we're
02:57 to be talking about cells that use pathways to send signals along their
03:04 But ultimately they signal via chemical Alright, So there's a distinction here
03:11 becomes very confused a little bit Alright, So electricals like what your
03:17 does, that would be kind of type of electrical signaling. What neurons
03:21 is they use electricity to create chemical . Alright, So with that in
03:28 let's kind of walk through them. going to the grocery store made a
03:30 giant list. So you wouldn't forget stuff that you do. No,
03:35 one. Okay. One person is their hands thank you. I'm not
03:39 only person who forgets stuff. I literally all day long I said I
03:43 I have something to do today and have something to do today. And
03:45 at the very end of the right before I went to bed,
03:47 like damn it. It was that thing that on the list and I
03:50 not remember. All right. I had to write it down,
03:54 had to tell myself what to do that's what the Quran signaling is now
03:59 means I am releasing some sort of out into the surrounding environment. And
04:05 that chemical then comes and binds back a receptor on that same cell to
04:09 that sell something to what to do you're sitting there. Why are they
04:13 the time and the effort? part of it is because the Quran
04:16 maybe coupled with other types of But really what you have to think
04:20 is that when you're looking at a , you don't have one thing going
04:24 inside that cell, right? You hundreds of things going on inside that
04:28 . So you may be releasing a to tell another pathway to turn
04:34 That is not part of the original that you're dealing with over here.
04:38 , so, it's just a way self communicate. Alright, so this
04:44 and this is gonna be true for single solitary one. In order for
04:48 signaling to work, the cell that receiving, the signal has to have
04:52 appropriate receptor. Alright, if you have the right receptor, you're not
04:56 to respond. I can send out right message all day long. But
05:00 you don't have the right receptor, just like don't know what it
05:04 Okay, so very, very easy the chemical signal goes out into the
05:10 interstitial fluid acts on a receptor on same cell released. It causes change
05:16 that cell that release the chemical Self talking. The next type is
05:24 we refer to as peregrine. Peregrine has. I'm just making sure
05:30 okay, peregrine refers to cells that or nearby. Okay, so here
05:37 , what I'm doing is, here's cell releasing, it's releasing a chemical
05:41 . The cells in the surrounding neighborhood gonna be responding to that chemical
05:46 Again, the key thing being that cell has to have the right
05:51 So, you can see in this cartoon up here at the top we
05:54 cells that don't have the right we have cells that do have the
05:56 receptor is the one that respond are yellow ones, not the pink ones
06:00 this particular picture. So, you're with nearby. Now, whenever you're
06:06 in general, any sort of chemical goes out into the interstitial fluid has
06:10 very, very small or short half , meaning you don't want that signal
06:14 be around to accidentally turn on something place in a in a in an
06:19 way. So, when we're talking peregrine, the distance for to which
06:25 that signal travels is very, very . Right? So, you can
06:29 if this is the cell right here the signal, this might be as
06:33 away as the signal gets. it's very nearby. Not very far
06:38 all. All right now, when talk about neurons, we're gonna be
06:43 about synapses and synapses. Just a form of peregrine signaling. I'm targeting
06:49 specific cell I wanted to to talk . You can see I have the
06:54 here but the interaction is nearby. very very close. They're not touching
06:58 other, they're very close to one . So synaptic signaling is a type
07:02 perricone signaling. Now, perricone signal to be differentiated from a type of
07:09 . That's a lot kind of like it's called Jacks to uh sorry,
07:16 stat signaling. All right now, difference between Para Quran and Quran is
07:23 Quran are cells that are nearby. a Quran are cells that are touching
07:28 other. Okay now, how are touching each other? Well, they
07:32 be touching each other specifically through direct . So here we can see a
07:38 . There's the ligand. The word . If I haven't said it to
07:42 again, just simply means the molecule binds to a receptor. It's a
07:47 term. Alright. It's like when say go to restaurants, I want
07:51 coke and then they ask you what and then you tell them like a
07:55 or dr pepper. Okay. I that doesn't fall that funny down
08:01 but if you're from the Northeast, like what you ordered a coke and
08:05 ask for dr pepper because they call soda or pop. Alright,
08:11 so here direct context. Just I'm going to have the two cells
08:16 each other. They're touching each other they have the appropriate receptor and
08:21 Right, So the immune system uses all the time. It's a process
08:25 referred to as cell to cell So these cells are basically moving around
08:30 the body and they come up and each other and if they have the
08:33 combination right receptor, right leg in one cell tells the one with the
08:38 . Hey, you need to be this and then they separate the one
08:40 the receptor goes off and does what needs to do. Another type is
08:46 cells that have gap junctions. Gap are simply a series of proteins that
08:51 arranged in such a way that you a gap or a passageway between two
08:56 . So what happens is is that chemical inside this cell isn't being
09:01 it's actually being passed from cell to . Now this is can be a
09:06 of chemical signaling. But if its , those ions moving from cell to
09:11 become electrical signaling because you have current from cell to cell. Alright,
09:17 gap junctions play that kind of unique . Now the type of protein is
09:22 a connection and they're roughly 20 types they can get kind of complicated and
09:27 but just think gap junction two cells to each other by a series of
09:33 directly so that materials can pass between and those two cells work together to
09:38 whatever job through that signaling process. then the one that I think is
09:46 interesting. What if you ever stay biology, this is the stuff that
09:50 spend all your time talking about is distance signaling. What we sometimes refer
09:55 as endocrine signaling. An endocrine signaling need that caffeine, endocrine signaling.
10:05 you have. You have your cell its chemical. That chemical goes from
10:08 interstitial fluid out of the bloodstream and the blood stream and then starts traveling
10:13 the body Now because of the mechanisms chemistry, physics and biology which we're
10:18 going to go into it kind of back and forth between the blood,
10:21 interstitial fluid and it kind of just around again. It has a half
10:25 so it can't stick around very But the idea is that eventually get
10:29 some distance, it's very far The cartoon can't make it very far
10:32 , but just imagine this is your , this is your new your
10:36 right? And so what's happening now that those chemicals will go out in
10:39 interstitial fluid. If there happen to cells with receptors then they will activate
10:44 receptors. And if there's cells that have the receptors then they'll add that
10:49 either be destroyed or will find its back in the blood and keep traveling
10:52 through the body until its half life done. Alright. So here,
10:59 we're seeing is a way for your to communicate very long distances to cause
11:07 activities. Now when we think about things we call them hormones, you
11:12 have heard of hormones, right? mean that's been your entire life for
11:15 the last six years, hormones write you do. Everything that goes on
11:20 your life is based on the hormone . That's right. This is the
11:29 system. What's interesting is it's not the endocrine system. Anyone here ever
11:35 melatonin? Yeah, I love that right? Melatonin is a chemical release
11:42 the brain to act on cells to the clock rhythms of your body.
11:48 . And there's a natural release of that comes and goes in waves,
11:54 of endocrine signaling. Alright, so nervous system and the endocrine system use
12:02 type of signaling to control how your works. Alright, here's an easy
12:06 if you ever, have you ever thirsty? Alright, well next time
12:12 water. Alright. What? That thirst is based your body saying I
12:18 dehydrated, I'm lacking the water in body. My solute concentrations have risen
12:24 the parlance of physiology, your osmolarity increased and that signal goes back up
12:31 the brain. The brain says hey need to fix this problem and it
12:37 releasing chemicals like valdosta rone. Anti hormone and a couple of others and
12:44 it does basically says, tells you hey I'm thirsty. So what do
12:49 do when you're thirsty? Well hopefully drink water me. I grew up
12:54 the age of soda. So I out and give me a big gulp
12:57 I drink that which has more salt it and it makes me even
13:01 Alright, so but yeah, that's idea is you drinking water, you
13:06 bring yourself back into homo static Now these chemicals are gonna vary in
13:12 and they're gonna vary in structure and will learn about more of these or
13:16 specific ones in A and P. . But if we come along and
13:21 say, oh here's one, you when we talk about the anterior pituitary
13:24 something like that? You'll you'll see talk about. Alright. But generally
13:28 we do endocrinology in A and To just to save you guys the
13:36 . All right, so those are types of signaling. How do we
13:39 about signaling? Alright, well we two different types of signaling mechanisms.
13:45 have one that's called metabolic tropic and that's called ion a tropic. When
13:50 hear the word meta bow tropic, do you think of with that first
13:54 the word meta bow metabolism. so there's something that's metabolic that's taking
14:01 when you hear the word ion a . What do you what you hear
14:04 that prefix? Ion oh, So it has something to do with
14:09 . Alright. This latter half the part doesn't refer to a drink,
14:14 ? With little umbrella in it. refers to something in response to it
14:19 causes an effect. Alright, so tropic means I'm creating a metabolic effect
14:25 the cell. Ion. A tropic I'm creating an ionic effect in the
14:30 . And so what we see in meta tropic receptor, which can be
14:35 of these different types that we just at or in an ion a
14:38 it could be in any the types we just looked at, any type
14:40 the signaling. But what happens here that that chemical signal binds to some
14:45 of receptor. So we have an signal acting on a membrane bound receptor
14:52 then causes some sort of inside And so the first step is simply
14:59 binding that receptor. When I bind receptor, the molecule that's the receptor
15:04 shape and it creates a cascade, like knocking over a domino in a
15:09 string of dominoes and a whole bunch other stuff is taking place. And
15:14 all those whole but other stuff refers a process called trans direction. Now
15:20 english, what trans junction simply I'm turning an outside signal signal into
15:24 inside signal, I'm changing one thing something else. So here it's inside
15:28 outside or sorry, Outside inside excuse , I got those backwards.
15:32 so I've got an outside signal that into an inside signal and then that
15:39 signal through a series of path or series of molecules. In other words
15:44 the dominoes begin to fall ill eventually some sort of unique response inside that
15:51 . Okay. And again we don't what that is right now. But
15:54 you think about whenever a hormone binds whenever a chemical signal binds it's going
15:59 change the activity of what's going Now. I'm gonna use a weird
16:02 . I've never used this example but just want to give you an example
16:06 our immune system. We have a . Cell. We have lots of
16:11 types of T cells. We have T. Helper cell. What do
16:15 think A helper cell does? It ? And then we have a side
16:18 toxic T. Cell. What do think a side of toxic cell
16:22 It kills cells. So the side toxic cell is already included in on
16:27 things but it doesn't know what to . And so what happens is that
16:34 helped her sell gets alerted when there's bad in your body and it's like
16:39 got to tell someone to go do about this. Who do you think
16:42 talks to side intoxicant? It binds it and it turns on that cell
16:49 takes an outside signal from here to and turns it into an inside signal
16:54 get this one all active and hot bothered for whatever it is that's infecting
16:59 body so that it can go hunt down and kill it. That's an
17:03 of a cellular response. Okay, just one. I mean we could
17:09 this all day with every part of body. Okay. But the idea
17:14 is I'm taking an outside signal binds a receptor that receptor activates something that
17:21 that's trans deduction. And then at end of all those pathways, those
17:27 I create a response that's unique to particular pathway. So what has to
17:34 in one of these things is that that's there in that pathway? That
17:39 pathway has to already be present in cell. Some of you were here
17:46 little early and the room was right? And what did I do
17:52 make it light? I pushed a over there. Right? So everything
17:57 make the room light was already here the room. All I had to
18:03 was push the button and that caused lights to come up. Lights were
18:07 there. The wiring was already It just needed something to transducer that
18:14 to make it happen. And that's happening in a meta tropic pathway.
18:19 . Typically what you'll see in a trophic pathway is a whole bunch of
18:23 molecules that need to be turned Right? So again, this is
18:28 . So the idea here, as can see here's my ligand, here's
18:31 receptor, my ligaments bound to the and it activates a molecule that's already
18:36 . That little p is a phosphor . Usually when you see phosphor relation
18:40 a molecule refers to changing it from inactive state to an active state imparted
18:46 . Alright, but you can see one turned got turned on which turned
18:49 that one which turned on, that which turned on, that one which
18:52 on eventually the protein at the very , which actually makes us the change
18:57 the cell. Now when I was here since I was like why are
19:01 wasting my time with all those Why can't I just turn on?
19:04 one thing? And the answer is we're looking at one pathway of several
19:11 . So somewhere along the line, one I'm just making it up,
19:14 be turning on a different protein that kind of the same thing that turns
19:18 a target over here and this one here turns another pathway on And maybe
19:22 one up here turns on three So when you're activating at the
19:28 you're not just knocking over one row dominoes, you're activating multiple rows of
19:35 and you're getting multiple effects and it's combined effect, which is what that
19:40 response is, is all those different being turned on. Okay, so
19:48 response refers to what happens at the of these cascades, that's what it
19:54 just a trans direction cascade is the that we use? Come on,
20:04 we go, finally you're gonna So the temptation here is to memorize
20:13 thing and I don't want you to it. What I want you to
20:16 here. I want you to understand idea concept, I'm a dad so
20:23 gonna use this example which lands perfectly me and as a child it hopefully
20:29 land perfectly for you. You go the room, you turn on the
20:33 and then you leave the room. are you supposed to do? Turn
20:37 off, Quit wasting my electricity. ever heard that 1? I do
20:43 all the time. Kids walk into bathroom, leave the light on,
20:48 into the kitchen, leave the light . You know you guys raised in
20:52 barn right for everything that gets turned in a signaling cascade. Remember what
20:59 done is I've turned on something and long as it's turned on it will
21:05 doing what it was designed to You don't want things turned on all
21:11 time. I imagine your house where is turned on all the time.
21:16 mean sure refrigerators, whatever. But the tv being turned on, imagine
21:22 ipod, you know really your phone on all the time. The music
21:27 stops. Imagine you're just everything. lights always being turned on, middle
21:32 the night, everything being turned Would that disrupt your home?
21:38 if you have a pet, do think you'd be happy with you?
21:42 are on all the time. Mhm . So, in our bodies,
21:48 we have are mechanisms for everything that's turned on. Everything is being turned
21:54 . So, when you think of pathways imagine not only am I turning
21:59 on, but there's something else that's it off and that's what this is
22:04 to show you. It's saying, here is a inactive protein, here's
22:09 active protein. There's something that turns on and now here's something that turns
22:15 off. And so there's these processes allow you this, what we refer
22:19 as molecular switches that turn everything back . So everything you turn on gets
22:23 off. Everything that you turned off turned back on. So there's all
22:29 things going on all the time. this is just an example of one
22:35 those ion a tropic receptors we said with ions. Yeah, it makes
22:46 easy once you start just attaching what words mean to what they are
22:54 Yeah. The first time I realized are that simple. It was like
23:00 I wasted all that time trying to things. No, they're telling
23:05 That's your own cheat sheet. The of things. Alright here notice what
23:11 have is we have a receptor that's actual channel. Alright, so little
23:16 hexagon things. Those are our All right. So when the ligand
23:23 to this channel, it serves as key. And when we use that
23:27 , we open the channel and that the ions to flow through. Now
23:32 ions are gonna flow based on the of diffusion that we talked about right
23:37 an area of high concentration to an of low concentration. So if we
23:41 a lot of sodium out here and is a sodium channel, then
23:45 when this channel opens up, sodium gonna go rushing into the cell and
23:49 something goes rest again in the it carries with it, its positive
23:52 . And so the inside of the becomes more positive than it was
23:57 That's a current. That's an electrical or an eye on a tropic
24:05 These are very short signals. It's of like when you open a door
24:08 you have the see if I can it up there. You have the
24:13 arm to force the door to right, you open it, you
24:18 go through but that door is closing behind you. And that's what this
24:23 is these types of channels are gonna for a short period of time and
24:27 they're gonna close up again, allowing to return back to a steady
24:31 And of course there's leak channels and sorts of other fun stuff that moving
24:35 back to where they go or pumps it were. But what we're using
24:41 is something to get a very very , very rapid response and this is
24:45 electrical signaling does. It creates rapid . A weird type of signaling and
24:54 is the last one. It's also ligand based signaling mechanism. But
25:00 what we're doing is we're dealing with lipid soluble substances. So in that
25:09 example, the meta tropic, we that the receptor was found up at
25:14 surface, right, It was right here. I'll just go back.
25:18 you can see and that's true for one as well. Alright. But
25:22 up here that Ligon can't penetrate through membrane membranes made of lipids. That
25:31 is water soluble so it can't go the membrane. So the reason that
25:36 have to have this pathway in the place is because we have to turn
25:39 outside signal into an inside signal. here, we have an outside
25:45 And what we're doing is we're creating internal response. But again, that
25:49 happens to be water soluble when we're with nuclear receptors. Come on
25:56 Stupid thing. There we go. we're dealing with nuclear receptors are molecule
26:04 lipid soluble. So in this particular they're trying to show it's a steroid
26:09 are lipids so a lipid can't stop lipid lipid, the steroids just gonna
26:15 right through the membrane and so there's need to have a receptor on the
26:19 , you can have a receptor inside cell. And so this is where
26:23 receptors come in now, what's unique nuclear receptors is you hear it in
26:27 name is like oh well they must in the nucleus. Yes that's where
26:30 work. But they can be found the cytoplasm or the side is all
26:35 can be found in the nucleus when unbound. So they kind of exist
26:39 just inside the cell. But when steroid, when that lipid soluble signaling
26:44 comes along it binds to it and that receptor moves to the nucleus and
26:51 finds another one just like it and what is called a dime er dime
26:56 means just to of all right. then when they come together then they
27:01 as a unique type of molecule they what is called a transcription factor.
27:07 transcription factors promote the production of new expression. Alright, so I'm gonna
27:15 the example again here of turning on lights. So if I was signaling
27:20 this mechanism to turn on the what would have to happen is is
27:25 of pushing a button the lights would on. What I'm doing is I'm
27:28 making the button and the wires and lights and I'm putting them all into
27:32 before anything can happen. So which you think would be faster turning on
27:37 lights with a button or making everything on the lights right? so this
27:43 of mechanism is now very slow, speaking, Alright, relative to the
27:51 tropic. But remember with meta tropic turning things on and I'm turning things
27:55 back off again. So I'm getting very quick response but I'm getting a
27:58 short lived response here. It takes while for me to make things but
28:03 those things are going to be stuck or going to stay around for a
28:07 time and so I have a long response. So these types of signaling
28:13 result in maybe not an immediate response it, but you get something that's
28:18 to be long lasting. So if use this type of mechanism when you
28:23 something to stick around for a Alright, so with nuclear receptors,
28:30 signaling molecule is lipid soluble, they to receptor that acts as a transcription
28:37 . I get new gene expression, takes longer to get my response but
28:42 sticks around for a longer period of . So those are very generic ways
28:48 look at how cells talk to each and it can be kind of
28:55 So I'm going to stop here. there any questions about what we just
28:59 through? Yeah, ligand? perfectly fine. What is ligand ligand
29:08 simply a fancy word for saying molecule binds a receptor, that's all it
29:15 . Alright, so when you say the ligand. Just that means there
29:19 be a receptor for it. anything else? Yeah. Mhm.
29:31 . So remember when we talked about proteins, when we talked about the
29:35 of of transcription, this is really that is. It's basically saying look
29:40 our gene of interest over here, is where we start reading the
29:44 N. A. And so in to read that D. N.
29:46 . We have to have something there turn on the reader and that's what
29:50 transcription factors acting as. Alright, gonna confuse you now. So just
29:55 can brain dump this. Okay, factors can be activators or they can
30:02 inhibitors. So everything that we've talked here, even in those transactions cascades
30:07 be activators and inhibitors. It's just , especially when you're first being introduced
30:11 the idea to think of everything as activators. But when you move forward
30:16 your academic careers you're gonna start seeing wait a second Doctor Wayne told me
30:20 is a pathway that turns things But you're showing me a pathway that
30:23 something off because that's what they can . All right. But it's still
30:28 pathway, it's the pattern that becomes . Not the specific players until you
30:33 at a specific pathway that makes Alright. So here this is the
30:41 that allows us to create that new expression and then what we get our
30:46 proteins that term you ready, you want to write this word down.
30:49 actually two words de novo. So novo in very very de novo means
30:56 new day and novo? Right. novo. And so what we're getting
31:02 de novo protein synthesis. The de protein synthesis synthesis. I'm gonna get
31:08 words out. Right? All So the gene expression results in the
31:14 of new proteins. So, if ever see de novo, that's what
31:17 means of new and then whatever is it in this case it's protein
31:23 Alright, so new jeans new Huh? And that's what you're seeing
31:30 . Right. Oh sorry. So question is so how do you stop
31:41 basically? Right, How do you this? We don't stop it at
31:45 level. Right. Because what happens here I'm gonna make multiple copies.
31:50 I'm just gonna make a couple of and then it falls off in a
31:53 . It goes all right. But I've got a whole bunch of copies
31:56 now I have the machinery that goes and makes multiple proteins. And so
32:01 you see here is you're not stopping at this end. You have to
32:05 for the whole process to go through stuff. But yeah, this they
32:10 only stick for a short period of . Everything has a short half life
32:14 in the in the cell for the part, Yeah. Mhm. That's
32:28 the question is for these receptors, there some sort of universal signal?
32:32 you ready to write this down? right. The truth is is that
32:37 specificity of a receptor is not It's not 100%. I'm just going
32:42 give you an example. It's so androgen progesterone. These are all
32:50 They can all buy into each other's including cortisol and other steroids but they
32:57 so with different affinities. Right? if I have a lot of estrogen
33:02 might actually activate an androgen receptor. I have them present, I just
33:07 activate them very well. All This can be true across many different
33:14 of molecules. Another one. Oxytocin closely related to another molecule called
33:21 In humans we have these two. in other animals the difference between those
33:26 molecules is one amino acid. And most other animals just have a
33:32 Like I think they have like the version. Right? Our oxytocin does
33:38 thing because it has its own receptor does another thing. It has its
33:42 and other animals. They basically use one. So can oxytocin vasopressin
33:49 Can the President buy into the oxytocin but not very well. But we
33:55 of take that step back from that just pretend like it doesn't happen.
33:59 . Because it's easier to pretend that if you were studying it or if
34:03 in an upper level course and you're to deal with distinctions like with biochemistry
34:08 stuff then you'd say yeah, there's some mismatch and some crossovers but there's
34:16 such thing as a universal signal but would be like closely related molecules,
34:23 else before I move on to this , I don't think what we just
34:27 is particularly difficult in a very generic . And once you learn those patterns
34:33 you start seeing these things over and again, it's just like, oh
34:37 I can here's where I memorize, the 12 molecules I have to memorize
34:42 it makes your life easy once you how they all kind of behave the
34:46 way. Right? I love that students take this course before endocrinology because
34:54 , they feel like they have to everything. But once you learn the
34:57 they're like yeah, endocrinology is Alright, so what we're gonna do
35:01 is we're gonna go through, we're look at how these cells attached to
35:05 other because cells typically are found as . And so we're gonna look at
35:13 epithelial cells because they kind of demonstrate the different types of attachments. Even
35:18 these attachments can be found in other . Right? So these are kind
35:22 the different types of attachments and we're gonna kind of walk through them.
35:26 want you to when you're looking at things look at what makes them distinct
35:30 each other. Okay, so the is the Dismas OEM Alright, this
35:36 cells firmly together. Now I described couple of days ago, the indian
35:40 . Right? And I may have some of you. And some of
35:43 realized that your lives were a lot than those of us who grew up
35:47 pre 2000 when we could beat each up and it was right. Remember
35:51 indian burn, That's where you grab arms twist and the skin doesn't come
35:55 off. Right. The reason doesn't falling off is because of these types
35:59 attachments right here, The Dismas ohm defined as basically some sort of cytoplasmic
36:06 which is basically a whole bunch of that we're not going to describe that
36:11 proteins that are called cell adhesion Right? These are the cat hearings
36:17 example. So the cameras, cell molecule. And then so the cams
36:23 basically attached to each other on each . So if this is cell number
36:27 cell number two, they're attached like . And you have lots of these
36:30 these cams that are attached to each and they're anchored into the cell with
36:35 plaque which is a whole bunch of proteins. And then attached to the
36:40 are a whole bunch of intermediate filaments go throughout the entire cell. And
36:46 you can imagine if I pull on cell that means I'm pulling on that
36:51 which then pulls on each of those filaments which disperses the force to other
36:58 that are attached to other cells which attached to other plaques which are attached
37:03 other intermediate filaments, which go to plaques and so on and so
37:06 And so this allows you to move or disperse tension and force within the
37:14 . And that basically keeps the cells being torn apart from one another.
37:19 right. So, when you think a Desmond's own, half of that
37:23 own belongs to one sell the other belongs to the other cell.
37:28 And so the general rule is that you see Desmond Zone, think mechanical
37:33 . Now, this next picture is the Desmond zone and it's a terrible
37:38 . But I think it shows you I'm trying to get at.
37:42 Because cells are not separate like Alright. But it shows you
37:46 is that would be where the Desmond's , is those little lines represent those
37:51 filaments? All right. And if I pull say on this
37:55 that cell is pulling on that one that one, on that one.
37:58 that one on that one. That . So, it's it's dispersing that
38:01 because all those intermediate filaments are connected each of those individual cells. That
38:07 of makes sense. Yeah, the Desmond's own is like the Desmond's
38:15 When you see the word hemi, does it mean means half.
38:22 it's half a Desmond zone. Now , what we've done is we've taken
38:26 that half of a Desmond's own that cell has but instead of anchoring it
38:30 another cell that has the other half we're doing is we're anchoring the cell
38:35 the underlying connective tissue. So up , you can see here is our
38:41 cell. There is it's half of Desmond's omits hemi. And then those
38:45 those cat hearings. And they're attached structures inside the next layer of the
38:53 tissue on which that epithelial cell And so it gets anchored in in
38:58 the same way. Right? And that force is now being dispersed to
39:03 connective tissue? Excuse me. All . So what is the substrate
39:13 This is primarily collagen and other molecules what we call the E.
39:17 M. E. C. Is extra cellular matrix. Alright.
39:23 , you can just imagine a whole of fibers and I'm basically tying ropes
39:27 those fibers. And that's why the doesn't slip around or move around because
39:31 anchored to the fibers in that next . Just half a Dismas. Ohm
39:38 to the connective tissue. I love of these names at hearings junction,
39:49 hearing. What do you think of hearing? Yeah. So when I
39:54 in your shoes or in your We didn't have it here injunctions because
39:59 didn't have technology that looked so close so deep into the cells, everything
40:03 a Desmond zone. And now as kind of go in deeper and we
40:08 the technology and we're like, oh , some of our Dismas OEMs aren't
40:14 OEMs. I mean we still have of a plaque, we still have
40:19 uh cam's, these cellular adhesion But instead of having intermediate filaments,
40:25 we have here is we have micro . And so an adherence junction is
40:32 to sell cells are adhered to one , it's more rigid and so it
40:39 the cells from even moving. It creates this attachment like a Desmond's um
40:45 a little bit stronger. So what's about this different proteins involved. And
40:51 the key one here that I want to understand is that it's micro
40:55 not intermediate filaments, tight junctions basically boundaries between cells. You guys have
41:14 with ziploc bags before. Right, good ziploc bags. Not bad
41:19 Alright, so you put something in ziploc bag, you seal the ziploc
41:24 , you turn the bag over and it like they used to do in
41:26 commercials. There's always gonna be like sauce over a white carpet. You're
41:31 to prove you that Yeah, that's of what a tight junction is.
41:34 basically a series of proteins. proteins on one cell, proteins on
41:39 cell and they kind of come together they create a barrier between the two
41:44 . So you can see here, can imagine if this was the top
41:47 the cell and that was the top the cell. Actually have a better
41:50 . I can't go between the two . So I I prevent the movement
41:56 materials between cells. If I want move things from one side or
42:00 I now have to go through the . This type of movement between cells
42:05 called para celular movement. Or if talking about moving down a concentration
42:11 para cellular diffusion, I'm going through cell, it's trans cellular. So
42:18 between trans through All right, what also does, It actually creates an
42:27 between the top and the bottom of cell. So the a pickle surface
42:33 unique relative to the basil lateral. how we said that we're going to
42:39 certain molecules to one side. So actually defines the two sides. I
42:45 create kind of a barrier that says a pickle. Everything below that is
42:49 lateral. Alright, so that's gonna direct movement of materials. And I
42:55 this picture here kind of shows that little bit better see how they actually
43:00 of created this kind of fuzzy pink in the picture. What that's trying
43:05 show you is that it goes all way around the cell. So it's
43:09 taking that ziploc and basically creating a right here that goes all the way
43:14 . So you can imagine sales behind so now you have a barrier.
43:17 now we have an outside and now have an inside. This is the
43:22 pickle portion. This is the basal portion. So, the environment out
43:26 is different than the environment in here we've created a strong barrier between the
43:33 things. Can't sneak in between unless is no tight junction. Okay.
43:42 , in saying that we can have type junctions which is an oxymoron.
43:50 , What do you imagine a leaky junction being like have stuff to leak
43:55 it? Yeah, it's not a . All right. It's a bad
44:00 bag. It's one of those generic you get at a TB ward
44:03 That if you turned it upside down shook it, you'd have spaghetti all
44:06 your floor. All right. Here's gap junction. A better way to
44:13 of see it again. This is to show you that they can actually
44:17 in open and closed states. Just any sort of channel does. But
44:21 can see here here's the inside of number One. This would be inside
44:25 number two. You can see cell one has these connection molecules that creates
44:31 ring and they're aligned with the connection of the other cell. So it
44:36 a passageway between the two cells. ? So now materials can pass through
44:43 thing is is that the things that pass through have to be small enough
44:46 pass through that channel. So it's limited to what it allows to pass
44:52 . Right, Just a couple of arms, 80 p maybe small molecules
44:59 Amino acids or glucose. That's about . It's not gonna allow big
45:04 So it's just a unique way to a way for these two cells to
45:09 directly to each other. And that's that little picture up there is trying
45:13 show you. So what I wanted do just as kind of the last
45:23 with regard to the cells and how associated with one another and how they're
45:28 , this kind of shows you the cellular matrix, this term that we
45:32 E C M. Alright. And what you can see is down
45:37 below, you can see the plasma . So everything down here would be
45:41 the cell. Everything up there is the cell. Now, remember I
45:45 you guys that video, I said watch this if you feel like if
45:48 go watch it, I think the even starts with you seeing the extra
45:52 matrix and it's like all these all these materials that sit outside the
45:57 . So it's basically water and So here you can see there's the
46:01 environment, you can see the sugars then what you have is you have
46:04 these proteins and you can see how have these adhesion molecules that attach to
46:10 proteins that are outside and what you now is you kind of have this
46:15 barrier. It's not like a dense but kind of like a screen door
46:19 kind of sits above the cells that the cell to interact with it and
46:24 this unique uh structure that it can itself to protect itself from, you
46:31 , or protect itself from other things this environment. And the cells themselves
46:36 secrete this out. So it has whole bunch of collagen in there,
46:40 bunch of other fibers. Um here have we see propio that's protein glide
46:46 refers to sugar. So these are sugars which helps hold water nearby for
46:52 cells. And then you can use as a signaling mechanism. You can
46:56 use it as a way to So when you hear the word basement
47:00 , you're gonna see that this has do with the extra cellular matrix that
47:05 cells have created. So it's anchoring that structure together. That kind of
47:13 sense. So, so what we here is we have did you say
47:18 ? Yeah. Yeah. He okay. How can I make it
47:25 what the cells secrete? Yeah. all right. So the question
47:31 is it basically with the cell secretes of All right, so let's say
47:35 and you want to anchor yourself to layer of tissue. How do you
47:39 that? Well, there has to something to anchor to how do you
47:43 something that that the the underlying tissue grab onto. So, what you
47:47 is you secrete proteins and you and have proteins and what you do is
47:52 group of proteins that are sitting on outside is kind of like if this
47:56 your cell, that's kind of that and you have proteins down here and
47:59 you've anchored yourself to it and so extra cellular matrix is that anchor?
48:07 all you gotta do is ask I'll try to find a better way
48:10 say it can't promise that. I'll it better. All right.
48:16 what we've looked at is we've looked how to cells attached to other
48:20 So we got Desmond zones, we Emmy Desmond zones, we have adherence
48:26 . We have tight junctions, you how every one of them sounds like
48:29 they're supposed to do with the exception Desmond's um right gap junction, it's
48:37 easy mode. Right. Good. . Any questions about these different types
48:44 connections? Because I mean, we one more thing and then we have
48:49 more class than we have a And our next class is we're gonna
48:53 at Yeah, I know is that ? It's like what? Yeah.
48:58 lectures in a test. Six lectures a test. Six lectures in a
49:02 . Six lectures test christmas when everyone stay. Remember? Uh It'll be
49:12 since december 1st. I mean if gets an a remember master party will
49:16 it december 2nd. There we That's what I'm looking for the rest
49:24 you didn't have confidence. All Last little bit. Where are
49:34 That's what I don't know. I'm up here. This is where the
49:37 is. Alright. Cell cycle. can be very, very confusing or
49:41 can be very very easy. We're to keep it on the easy
49:44 Not on the confusing side. so this is not looking in a
49:49 and asking and I'm not gonna ask , memorize all the different stages and
49:52 able to draw them. Please don't that. All right. What I
49:55 to understand is that cells have this to replicate. Not all cells are
49:59 be replicated or some of cells are my topic. I'll just put it
50:04 way. All right. So, you look at a cell, its
50:08 basically is divided into two parts a of metabolism and growth and then a
50:13 of division. Alright, So there's period where it's just kind of doing
50:16 thing and then it's like, it's time for me to divide and
50:19 it goes into this unique thing and after division, it goes back to
50:22 uh metabolism and growth phase. And we have names for those, the
50:27 is the metabolic phase. That's the phase. Alright. So, you
50:31 imagine here, this is when cells just kind of doing what they're supposed
50:34 do and then when it's time to , that's when they go into the
50:38 topic phase. All right. So the cell division. And so when
50:42 talking about the cell cycle, what really do, and I mean,
50:46 , like I said, it can into a lot of depth here,
50:48 not going to is that there are and interesting things that are occurring through
50:53 main topic and through the interphase. , the first thing I just want
50:59 kind of point out here are the sub phases. And I would point
51:03 that the sub phases have sub phases have sub phases and we're not gonna
51:07 that far. So, this is sub phase. I want to look
51:10 the interface. All right. when you enter if you're selling you
51:15 into the interphase. If you're replicated if you're in a replicated cycle,
51:20 you're gonna do is you're gonna go the G one. So, that's
51:24 first growth phase into the That's scary that happens. I have lots of
51:34 though. Yeah, the key one is the Orange one. If that
51:39 goes then we're not recording. All . So, If you're like a
52:03 that's constantly replicating itself, making copies dividing and dividing. You're you're not
52:09 gonna pause. You're just going to of move through them. So the
52:12 phase is just called the G1, is the first growth phase. And
52:16 you're doing in there is you're doing normal cell activity. But you're also
52:21 yourself for that rep. the And so the period in which you
52:27 synthesize and get your DNA ready is the S phase. Right? That's
52:33 it's called the synthesis phase. What you're doing is you're taking
52:36 you can imagine every cell has its . N. A. It's two
52:39 . I mean, it has the its chromosomes. And then what we're
52:42 do in the S phase is we everything. And then the G.
52:47 phase is basically saying, all I've made a copy of all the
52:50 . N. A. Are we to actually go forward? All
52:54 Are we ready to enter into the phase? Because if we don't have
52:58 ready to go, then that's gonna up that division and then we're just
53:03 have to destroy the cells. All . So, the idea is that
53:07 phase is kind of preparing for the one. Moving forward. So normal
53:11 cells are maturing, they're doing their . I copy my D.
53:15 A. In the S. And what I'm doing is I'm going through
53:17 going through my checklist and making sure is ready to move forward.
53:22 So G stands for gap or growth that's just your normal activity over
53:29 You can see this thing little air on site. So some cells are
53:34 in a normal replicated cycle. All . So, if you think of
53:40 skin, for example, your skin constantly replacing itself. So there is
53:45 layer of cells that are constantly going this. Making new skin cells.
53:51 . But your neurons are not. so what happens is is during
53:55 you make all your neurons and then happens, your neurons go over here
53:59 they sit outside the cycle. And this is called the G not
54:03 So, there is no division and basically paused there or held there.
54:09 , once you're going to G you stuck there some cells can return
54:13 into the cell cycle. Some cells not. All right. So,
54:18 just think of G zero is being of the natural cycle of replication.
54:23 one S G two is part of normal cycle of replication. All
54:32 Now, I would point out there checkpoints. So, in G one
54:36 a checkpoint that says, are we to move in? Right. So
54:40 do do we go this way or we go that way? And G
54:43 ? Um it basically says do you all the stuff if you don't we're
54:49 letting you move forward. It's kind like passing a class. Right.
54:52 you pass the class? Yes. , No. You didn't. All
54:55 . You don't get to move You have to go back and make
54:58 you do that. Although I think they don't actually say they usually kill
55:02 the cell. So this goes to next thing is mitosis. Alright,
55:08 mitosis is the process of cell division it's a very, very orderly
55:15 And if you when you were in , when you took, when you
55:19 biology, most of you took biology sophomores, if you took it,
55:22 probably looked through a microscope, they give you a whole bunch of
55:25 You have to sit there and draw each of the individual stages and stuff
55:29 you're probably sitting there half the time , I'm not sure exactly what I'm
55:32 at. And so you just kind drew it and hopefully you got
55:35 Right. So, I'm less interested your understanding all the different phases first
55:40 . You should just know them in . So, it's pro fes meta
55:43 and phase to a phase. Easy to remember its ip ip for
55:46 right, hip matt. And you memorize that tattoo it to your
55:50 whatever it takes. All right. the idea here is that we're going
55:53 go through these stages. And the is we're gonna take that DNA that
55:59 . All right, We're gonna align in the center so that we can
56:03 the D. N. A equally two parts. Right? And then
56:07 can split the cytoplasm into two parts well. Alright. So that we
56:12 up with two daughter cells that are clone of the original cell. All
56:17 , that's the idea. Alright, pro phase is basically the breakdown of
56:24 nucleus. The meta phase is basically alignment of the DNA before we split
56:29 apart. And a phase is basically period where we're splitting the DNA apart
56:34 phases, basically we're trying to reorganize cells into their proper structure, so
56:39 going to recreate the nuclei and then gonna split that. Um um the
56:44 is all equally between the two daughter . So that's kind of the big
56:49 stuff, but there's a lot of in there and I just want to
56:53 out, you do not need like, pro fes has six sub
56:57 in it. Right? So it really confusing. So if you don't
57:02 what you're looking for and you haven't taught this stuff, it's like,
57:06 , I don't know. So if just keep it simple breakdown,
57:09 line things up, split things apart try to form two new cells,
57:13 probably in good shape, right? you're actually studying this material.
57:19 I pointed out here, these two and I put something in different colors
57:25 highlight them. And it's this word . Sido sell kinesis is movement of
57:35 sort. And what we're doing here psychokinesis refers to the process of breaking
57:41 cell apart into two. Alright, we're gonna start here and it's not
57:49 shown but we're going to continue it so that we get those two daughter
57:57 . So mitosis and the steps of refer to nuclear division. Alright.
58:05 you hear the word mitosis, think dividing the D. N.
58:09 So I copied the D. A. In the S. Phase
58:12 interphase or write the S. And then now what I'm doing is
58:18 splitting it in half. So if doubled it now I'm returning back to
58:23 original number. So that's really what job of mitosis is. And then
58:30 . So nuclear division mitosis, psychokinesis cellular division. It's the vision of
58:35 cytoplasm. Alright. And that's gonna very early on in an A phase
58:42 really kind of midway through an A and it continues on through the tele
58:47 and then once it's finished now you your two cells and now you're back
58:51 the interface and you're repeating that process over again. So picture up here
58:57 terrible because it doesn't show that. you should start seeing a cleavage
59:03 What does that mean? Think of this way? I took a lasso
59:05 the nice texas example, took a . I wrapped it around the cell
59:09 now I'm squeezing the lasso, that's it's doing, it's it's gonna split
59:14 half questions about this. Yeah. here you can see it clearly
59:26 I mean they're the artist is like I've done it. But it's really
59:30 here. The artist didn't draw it the picture. So use this say
59:37 that little divot. That's the cleavage . Alright. And basically what I'm
59:42 , I'm splitting the cell in half . What did I split in half
59:49 nucleus? Alright. I've divided the N A two equal halves. That's
59:55 idea. I hate using the word because X chromosomes and y chromosomes are
60:03 exact. All right. Yeah. can do that. We're done.
60:12 today's lecture. Well done early. . Yeah, fine. That's how
60:18 how you feel. Okay. I even give stories or anything certain the
60:34 division. It's just and we just it So cell division side of
60:38 The nuclear division is mitosis. I think it's on the other
60:43 it's actually the title of the other . Yeah. Oh yeah. So
60:46 can just you can put nuclear Yeah, that's that's really what it
60:53 to but we kind of refer to as the whole process even though it's
60:58 . Yeah. Yeah. Any of um so you probably need a different
61:06 . You try. Alright, email . Uh support at video points dot
61:12 . Remember? It's just a grad sitting over in the computer science
61:15 so we'll get back to you pretty . This is not like a
61:18 Right? So support. Alright, it's called Video points dot org.
61:24 ? And then just say support. at So support at video points dot
61:33 . Yeah. And they should get . They should get right to
61:36 Alright. Just saying I can't view things I've tried in this brother,
61:40 brother, this brother. And they say, oh, you need to
61:42 these steps. All right. No. So typically, I
61:49 I know they do that in other , but here we don't do
61:52 So you can just think of it way is all those questions I'm giving
61:56 those open ended questions. They're kind forcing you to do review along the
62:01 . That's that's my hope. And then so what we'll do is
62:04 talk on Tuesday. Everything through Tuesday be on the exam. Alright.
62:10 hopefully this last lecture is not gonna too hard. It's again, it's
62:13 here's tissues. Yeah. Yeah. . So yeah. You still haven't
62:29 it. Okay. Just do what can. As soon as, as
62:35 as you get it, let me . So it came by. It's
62:38 by mail? Oh, okay. . Yeah. Go to go to
62:45 bookstore and say, what the I'm three weeks. I'm three weeks
62:48 class. Why haven't I received Give them the frowning face, you
62:51 , just like Yeah, because I and they're probably gonna say,
62:54 there's nothing we can do. But what what what it does is
62:58 this is something that I'm suppose to now I've got a I've got a
63:02 next week. We're three weeks into . Come on, where's my
63:05 I've used the free trial up. me, you know, and and
63:08 they'll help you out. But then you get it, just email me
63:11 soon as you can and we'll try help you out, okay? You're
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