Overview of cell signaling

what I want to do in this video is give ourselves a quick overview of the different ways that cells can communicate with each other and maybe the most basic one is just through direct contact direct contact and this can happen several different ways one way it could be you just have neighboring cells so this is one cell right over here and this is the neighboring cell right over here and they actually might have gaps in their membranes if these are plant cells we would call these gaps gap junctions so you might have I just drew two of them and this is obviously just kind of a two-dimensional slice so we're not fully appreciating the 3-dimensional structure but the basic idea is is maybe the cell on the Left starts producing some molecules especially some small molecules that are able to go through these gap junctions and when they're able to go to through the gap junctions maybe they latch on to some proteins in the second cell that start maybe activating them in a certain way or inhibit them in a certain way or trigger some type of reaction and so then you have a response in the second cell so this would be a form of communication something happened in this first cell to produce these molecules those molecules were able to get into the second cell and trigger a response and as I mentioned if these are animal cells we would call these gaps we'd call them gap junctions so that right over there that is a gap junction gap Junction now we cover this in other videos and if we're talking about plant cells we can have very similar things happening but we wouldn't call them Clapp gap junctions we would actually need to be gaps not just through the not even tunnels through the membrane it would also be through the cell walls if it were talking about plants they would be plasmodesmata plus mo des Matta and we talked about these more in the structure of cell videos but there's other ways that you could communicate via direct contact you could imagine maybe some cells that are floating around in the bloodstream maybe this is one cell over here maybe maybe this is another cell over here and they have complementary surface proteins surface proteins that are able to bind to each other so maybe this one has a surface protein that looks like this I'm obviously exaggerating its shape the protein wouldn't look exactly this inverted triangle but this one has a surface protein like this and I'm also exaggerating its size relative to a cell just so we can appreciate how they could maybe lock together so this one has a surface protein like that and when they bind to each other it might change the proteins in some way and then trigger a reaction in each of these cells at the communication then continues if this protein changes a little bit it might activate something and might activate the release of some molecules might activate some other proteins might catalyze some type of reactions we've seen this in multiple other videos all sorts of crazy biological reactions can happen inside of cells but it might elicit a it could elicit a response and actually could even elicit a response in both cells some type of response they know that they are latched on they know that they're latched on to someone else now direct contact you could imagine is not the only way that you could have cell cell signaling you could actually have cells start to signal out over a little bit of a distance by releasing molecules into the extracellular space and eventually even into the bloodstream so for example let me draw a cell cell right over here and maybe it's able to produce some molecules and these molecules either they might be lipid soluble and maybe make their way through the cellular membrane on their own or maybe they are packed in Nice vesicles that allow them to traverse the membrane so when you get actually so the membrane of the vesicle merges with the membrane of the cell and then it allows these things to get out and so you can imagine if another cell has the right receptors for these that would signal that would signal some type of a response or it will form some form of communication so let's say that I have actually only talked a couple of cells so let's say I have this cell over here and then I have this cell over here and let's say that this cell has the right receptor has the right receptor and this cell doesn't it could have other receptors maybe it has receptors like that but it's not the right receptor and so these these molecules that were released by this first cell could bind not on this character not on this protein the surface protein but it could bind on this character so it could bind on this character and what it does so this protein that's on them on the on the cellular membrane it might change its shape it might do all sorts of things but that signal can be then taken somehow be it can be it can continue on into the cell and once again you might elicit some type of response and we'll go into more detail in future videos on exactly how that happens or what these responses actually might be now if this is over if this is over a short distance if this is over if this is a short distance short if this is a short distance short distance we would call this Peregrin this would this would be fought part of the paracrine system or we would call this paracrine communication let me write that down para Crenn para current system or para Crenn communication or paracrine signaling and we would call these paracrine factors but if it was happening over long distances say maybe these these molecules they enter into the bloodstream so they make their way into the bloodstream right over here so let me depict somehow that this is the blood stream so this is the blood stream blood stream and they're able to make and they're able to go through the blood stream over longer distances to other molecules to other molecules so maybe this one has the right receptors for those for those for those molecules then we call this endocrine system or this is endre can signal e so long distances long long distances we would call this the end ricchan system or endocrine endocrine signaling endocrine signaling and we're talking about the endocrine system and endocrine signaling these molecules which could just be you know there could be all sorts of different types of molecules it could be steroids they could be proteins of some kind we call in this case we would call them hormones and you've probably heard the word before and we will do a whole series of videos on hormones but these molecules actually can even affect the cell that produced them for example the cell that produced it might have the right receptor might have the right receptor and so if it's able to signal if it's able to trigger a reaction in itself so if these things are able to trigger a reaction in itself we would call that an autocrine process auto-create it is acting on itself and just so you're familiar with some of the terminology these proteins on the surface and this would be the case especially if you have a if you if you have non lipid soluble types of signaling factors or molecules right over here these proteins well actually even if they're on the surface or even if they're within the cell we would call them receptors so that right over there that is a receptor receptor and the molecules themselves these things that bind on to the receptor we call them the ligand ligand in general it's a general term for something that binds on to a receptor and so what at that point where you bind on to a receptor whether you're talking with a parrot or a para can process or endocrine endo actually endo I love to see out here endocrine signaling the this this process where it kind of starts to where it latches on we would call that a signal perception and then when this protein you know somehow changes its shape or starts catalyzing a reaction or inhibiting a reaction we would call this the signal transduction transduction it's bringing the signal into the cell and then you have and then you have your actual you have your actual cellular response so hopefully you appreciate that is just a bit of a an overview of how cells can signal with each other and in future videos we'll go into a little bit more detail especially the endocrine system and our understanding of hormones