1. Topic 14 – Off to Parts Unknown
The Lymphatic System
Topic 14 – Off to Parts Unknown

2. Fluids The body is composed of mainly water (60%).
We learned that nutrients and gases are exchanged through the capillaries.
Interstitial fluid is plasma that has left the capillaries; it occupies the space in between the capillaries and the cells.
This fluid is what allows for the exchange between the blood and the cells.
Lymph is the fluid that can be found flowing through the lymphatic vessels; it is composed of mainly water.

3. Function This system includes vessels, organs, and lymph nodes.
The lymphatic system is responsible for carrying lymph throughout the body.
Carries antibodies and some white blood cells to neutralize antigens.
Transports fat molecules.

4. Vessels Lymphatic vessels are like blood vessels.
They are located near the blood vessels.
They carry lymph throughout the body (like highways and roads allow for cars to get around).
They also return the lymph to the blood.

5. Lymph Nodes & Organs
Lymph nodes are small bumps located in the neck, armpits and groin. They are also referred to as lymphatic ganglions. When there is an infection in the body, the lymph nodes harden and become swollen.
Lymphatic organs
Thymus
Bone marrow
Spleen
Tonsils
The lymph nodes and the lymphatic organs help to protect the body because they contain a lot white blood cells and collect cellular debris and bacteria.

6. The Immune System
The immune system is composed of the lymphatic organs and vessels, as well as any thing else that serves to protect the body from foreign invaders.
The body’s ability to protect itself is called immunity.
Antigens are substances that can cause a reaction by the immune system. Antigens can be viruses, bacteria, abnormal cells or any other foreign substance.
An antibody is a substance that can neutralize an antigen. They are produced by white blood cells.

7. Non-Specific Immunity
Non-specific immunity is the body’s ability to protect itself against a variety of antigens. An example of this is the skin.
Diapedesis: white blood cells moving in or out of the capillaries.
White blood cells form projections called pseudopods.
Phagocytosis: the process by which white blood cells surround and destroy antigens.

8. Specific Immunity
When the human body can defend itself against specific antigens, this is called specific immunity.
How can you get specific immunity?
Naturally
If you have previously had an infection, the immune system has a memory of the antibodies that the white blood cells produced. If the infection enters the body again, then the body is able to quickly produce the antibodies.
Artificially
Vaccines contain weakened antigens that will not harm the body or cause illness, but will trigger the production of antibodies.