Cell Signaling

00:01 Extracellular and intracellular signaling.

00:05 We’ll discuss how cells speak with each other and deliver communique.

00:10 This could be in close proximity or those that are far away in the body.

00:15 Also, cells need to communicate vital information within the cell.

00:20 And how do they do that? These will be covered within.

00:28 There are many modes of communication.

00:31 You can come up with a lot of these on your own.

00:33 Some of them are personal in nature such as a handshake, other ones involve things like a delivered package or envelope, or even on the internet you can communicate very easily with a number of friends at the same time.

00:48 How do these communique work? Well, one of the things to think about with the body is what modes of communication does it have.

00:56 One of the more vital ones are endocrine control.

01:00 Here, you release a signaling molecule or a hormone.

01:04 It travels around in the bloodstream and is delivered to certain target cells.

01:09 How do you know which cells will get the communique? The ones with the right receptors.

01:15 If you don’t have the right receptor, you won’t receive that information or that signal.

01:22 Neural signals are also very important.

01:24 Here, a neuron can signal via long projections of axons going to an axon terminal and then releasing a packet of information to the cell it’s trying to signal.

01:39 These neural signals are very powerful in that they are direct communications rather than just releasing the substance into the blood, letting it travel around throughout the body.

01:50 Here, it’s more targeted in nature.

01:54 Now, if we move to some more local control, these are signaling molecules that will signal varying cells right around a cell.

02:05 This involves passive diffusion in which a molecule is released from the signaling cell and will only be able to diffuse in the distance around it.

02:16 Which particular cells will receive the communique? It’s all based upon the receptor.

02:22 You need to have a receptor to catch that signaling molecule.

02:28 Interestingly, there are also times in which a cell will want to receive the information that it is releasing.

02:35 A good example for this, if you’re releasing signals, you would want to make sure you knew how many signals were released.

02:43 You could have a receptor on the own cell that is sending these out to get feedback about that information.

02:53 Now, besides sending a signaling molecule, you could also have direct contact with the cell next to you.

03:02 Some of the direct contacts involve things called gap junctions.

03:07 Gap junctions are these specialized tubes that allow communication between two cells like it’s not even leaving that cell.

03:17 So these tubes will communicate electrical information, sometimes its ionic information, and this will allow a propagated and coordinated response between a number of cells.

03:33 Some direct signaling can happen via paracrine mechanisms.

03:37 For these paracrine mechanisms, you have to have one cell that can move around and be able to recognize another.

03:45 So the immune system is a very good example, where you might have immune cells that can travel around and recognize other cells based upon what projections they have sticking out.

03:57 Here, it’s like a handshake, where one cell will get up to a close proximity to another and if they can recognize each other’s projections, they might be able to bind and signal each other.