The Lymphatic System

1) The lymphatic system consists of lymphatic vessels and organs which serve to return fluids from the body back into the blood stream.

Lymphatic Vessel Figure

2) Lymph is the fluid that is carried inside of the lymphatic vessels.

The Lymphatic System

3) Lymphatic capillaries meet with blood capillaries in capillary beds to return fluid to the blood.

4) Lymph nodes are connected to the lympatic vessels. Lymph nodes serve mainly to filter bacteria and viruses from lymph before it returns to the blood stream.

Labelled Figure of a Lymph Node

5) Each person has about 500 - 700 lymph nodes in their body.

6) Lymph nodes contain macrophages and lymphocytes. Macrophages are white blood cells that destroy bacteria and viruses. Lymphocytes are white blood cells that secrete antibodies to target bacteria and viruses for elimination.

7) Lymph nodes are kidney shaped, about 1 inch long and have an inner part (the medulla) and an outer part (the cortex).

Lymph Node Anatomy Figure

8) There are other organs which play a role in the lymphatic system including the spleen, thymus, tonsils and Peyer's patches.

Labelled Figure of the Lymphatic System

9)The spleen filters blood, breaks down worn out red blood cells and serve as a reservoir of blood. It is found in the abdomen.

10) The thymus gland is located in the throat, just above the heart. During childhood it produces hormones that aid the development of lymphocytes of the immune system.

Thymus Figure

11) The tonsils are found around the mouth and also filter and destroy foreign agents (bacteria and viruses).

12) Peyer's patches are found in the small intestine and also function in eliminating bacteria.