Here we have systems that provide transport and immunity. First up, we have the circulatory system, also known as the cardiovascular system. Alright. The circulatory or cardiovascular system is made up of your heart, arteries, capillaries, veins, and your blood. Basically, you have a pump, your heart, that pumps blood through blood vessels.

Now it does that to transport materials to the body. Now what materials? I'm going to put in parentheses here, O₂, because that's what your blood is most specialized for carrying. That's what red blood cells are for. But your blood is going to carry all sorts of materials.

It's going to carry waste. It's going to carry nutrients. It's going to carry hormones. It's going to carry water, and so on and so forth. Anything in your body that needs to get from one place in the body to another is probably going to use the circulatory system to get there.

Now, we have a sort of what's sometimes called a secondary circulatory system, and that's our lymphatic system. Our lymphatic system is made mostly of lymphatic vessels, and those are largely designed to transport water. Your circulatory system lets out a lot of water into the extracellular space of your body, and it starts to collect there. And to keep you from blowing up like a water balloon, you have these lymphatic vessels which sort of funnel that water back up and then put it back into the circulatory system. Now, we put here the immune system as part of the lymphatic system.

The immune system is kind of funny because it doesn't have a lot of or it doesn't really have large organs of its own. It's comprised of all these sort of independent cells that are traveling throughout the body. So we put it with the lymphatic system because one way that the immune system travels through the body is through these lymphatic vessels. And there's specialized structures of the lymph system of the lymphatic system that the immune system uses. Those are going to be lymph nodes, tonsils, thymus, and spleen.

Basically, these things are places where the immune system can sort of stage fights against infection or be specialized places where they can fight infection. You're probably familiar with when you get sick, you might get swollen lymph nodes. That's because the immune system is collecting in the lymphatic system to fight an infection. Okay. With that, we've done transport and immunity, and I'll see you in the next video.