So now that we've talked about why we need the lymphatic system in our last lesson video, in this video, we're going to talk about what it is exactly. The lymphatic system is a network that primarily maintains fluid balance in the body, and it also aids immunity. These are the two primary functions of the lymphatic system. However, the lymphatic system also has additional functions that include absorbing dietary fats. As we move forward in our course, we'll get to talk more about these additional functions. The lymphatic system includes the following three components, which are lymph, lymphatic vessels, and lymphoid tissues and organs. Lymph is the clear and colorless fluid that's formed when interstitial fluid enters lymphatic vessels. Notice down below, we have a silly cartoon that helps us differentiate interstitial fluid from lymph. In this silly cartoon, the green structure that you see here represents a lymphatic vessel. The circles at the bottom represent tissue cells, and the yellow fluid immediately outside the tissue cells represents the interstitial fluid, which I will abbreviate as IF. When the interstitial fluid makes its way into this lymphatic vessel, it's now referred to as lymph. The biggest difference between lymph and interstitial fluid is its location because in terms of its contents, it's essentially the same.

The next component of the lymphatic system are the lymphatic vessels, which are tube-like structures similar to how blood vessels are tube-like structures, but instead of carrying blood, the lymphatic vessels carry lymph to veins near the heart. Ultimately, it returns leaked fluids and proteins back to the blood, and this is a function that we'll get to talk more about in our next lesson video. The last component of the lymphatic system are lymphoid tissues and organs, which include structures such as lymph nodes, the bone marrow, the thymus, the spleen, tonsils, and MALT, which stands for mucosal-associated lymphoid tissues. As we move forward in our course, we'll be able to talk a lot more about all of these different lymphoid tissues and organs. If we take a look at this image down below on the right-hand side, notice that all these green vessels that are projecting throughout practically this entire body here represent the lymphatic vessels. You can see that we're labeling the red bone marrow at the end of this long bone here, the thymus is also being labeled right here in this location, lymph nodes are going to be these bean-shaped structures that are found all along the lymphatic vessels, and the spleen is labeled right over here. Up here in the head region, we're labeling the tonsils. Again, as we move forward in our course, we'll talk more about all of these different organs and tissues, so don't worry about that. This here concludes our brief lesson on what the lymphatic system is. As we move forward in our course, we'll be able to apply these concepts and then talk more about the functions of the lymphatic system. So I'll see you all in our next video.