Lymphatic System & Immunity

In the last few units, you learned about blood and how it moves through our bodies. You learned that blood plasma tends to leak out into the extracellular tissues of our bodies as it travels through our systemic circuit. You also learned that we have leukocytes in our bodies that are involved in fighting off infection. In this unit, we will complete the exploration of these concepts by learning how any lost plasma fluid is picked back up and how leukocytes can fight infection.

This unit starts off with the easier portion-- the description of the anatomy of the lymphatic system itself and then how it works in general. As we move on from the lymphatic system to the immunity section, it gets a bit trickier. You see, there is a lot of cellular and molecular level information to digest in order to understand how infections are fought off... and I know you don't always love the cellular and molecular stuff (although I do!). But, infections are fought at the cellular and molecular levels, since it is leukocytes that have to discover and deal with any infective agents. These leukocytes not only use phagocytosis to destroy the invaders, but they also form antibodies, which are molecular tags to mark the invaders for destruction.

Here's the layout of this unit:

Lymphatic System

	General anatomy
	Lymph (formation and movement)
	Lymph nodes (structure, location, and function)
	Thymus and spleen-- important lymphatic organs

Fighting Infection

Nonspecific defenses

Specific defenses: Immunity!

lymphocytes

cell-mediated immunity

antibody-mediated immunity

	What's an antibody?
	How do antibodies work?
	Immune responses
	Other immunity issues: types of immunity, allergies, tissue rejection, and autoimmunity

OK... now let's get started!

Please note that this unit is undergoing changes...

The NIH (National Institutes of Health) has put up a set of web pages about the immune system that will be quite helpful for you. Take a look at their immune system pages.