Hello biology class, welcome back to another lecture. This is lesson two of the circulatory system. Components of the blood part two, the blood is very complex, so this is the second part of what makes up the blood. We are going to focus on platelets which is all about clotting and then a condition called hemophilia, which again is all about clotting. So that's essentially what this lesson is about. So we're going to continue from number three, this is number four, platelets. So platelets are very, very small. They are the smallest cellular components that aren't like nutrients or vitamins and things like that, and they are key point one. They have no nucleus, they are essentially little spikey things as you can see in the diagram and they live anywhere between five and nine days. They get filtered out by your kidneys, liver, and spleen again after that. They are produced in the bone marrow just like our urethrocytes, which are red blood cells and leukocytes, which are white blood cells, and there are about 250,000 platelets per milliliter of blood. So they are very, very small and there is a lot of them. And the reason that there is a lot of them is because they may need to clot a large portion of a bleed. So platelets are responsible for the initial stages of blood clotting and they're spiky nature will be very helpful for that. So platelets and clot formation, blood must have the ability to fix wounds. They are the wounds are made when blood vessels are opened. So there are four components involved in the clotting process. Platelets, clotting factors, fibrin, and then other cells will clump that in. Check out that video. It is essentially an animation of how this all works, but we'll discuss it as well. So platelets are self-ragments. They are small and essentially when you have an open wound they react to the air and become sticky. They form the initial plug. They're very spiky so they can connect to each other. They can connect to other things. You can imagine very spiky cells maybe grabbing onto a red blood cell as it flows by and holding it there and then other things getting stuck on it as well. So platelets are spiky. They get caught on one another and that's kind of activated by blood. Clotting factors are next key point two. There's 12 of them and they are proteins that jump in and reinforce the platelet plug. They all have different jobs. Maybe similar more like blue. This is very simple obviously compared to what the actual process is. Maybe others are like anchors, but they essentially latch onto platelets and help with the formation of the clot. We then have fibrin which is a mesh or a web-like protein that strengthens the clot. It goes over it and kind of holds that in place. And when we have fibrin we call that coagulation in the blood. So that is essentially a stronger plug at that point once the fibrin is there. And then there are other cells that get caught and white and red blood cells get trapped by the platelets, by the fibrin and they add to the structure. So that's why your scabs are red because they're mostly red blood cells by the end of it getting trapped. Again check out a video. Not sure which one is the person using the cards and explaining, but this one or the other one, but they both give another explanation, another point of view on how this all works. So here we have the three different parts. This is obviously the red blood cell. This is the white blood cell, the large chunky thing. And here we have platelets. These in reality are a lot smaller than the picture shows, but you can see how spiky and hooked they are. Here's something that would be seen in the hospital quite right you literally is a very, very swollen knee. And what happens here is between the joints, there's an injury and a little bit of fluid builds up. So this is what would happen with a normal injury to the knee. You might get some tingling, some heat, it might be swollen, I'll just a little bit, but we would be able to clear that out. What would happen if you have hemophilia, which is key point three, is there would not be clotting available. So clotting can't happen when you have hemophilia. So you'd get more and more blood in this injury and you'd get a boggy swollen muscle wasting area, stiffness, chronic pain and limited movement if you don't drain it. It would look like this essentially. That's why this person is here. So one blood disorder is hemophilia. It is inherited, so you get it genetically and a specific blood clotting factor is lacking. It is a deficiency that abnormally delays goagulation when bleeding occurs whether it be internal or external. So that right here is an internal bleed and there's no clotting, but if you get a big cut on your arm, you may also not be able to stop the bleeding there either. The result is that bleeding is difficult to stop when you have hemophilia. There's lots of people affected, mostly males and treatment can be given. You can give clotting factors and other help for that. But the biggest concern with hemophilia is that there will be internal bleeding. Let's say you're in a car accident and there's a small bleed internally. That normally wouldn't be too bad for people. That may be a large problem as there's no way to stop it and it may cause a lot of blood to pool in the abdomen and just cause a lot of problems. Internal bleeding is a very large concern with hemophilia as it doesn't take much to cause a body bruise and that can be life threatening for a person with hemophilia. So I'd like you to do some research on it. I've said a lot about it already but definitely go in and go into more detail and answer the questions and let me know if you have any questions or if you need any help. Thanks very much for watching everyone. That was kind of shorts. So enjoy and I'll see you soon.