Chapter 10 - Lymphoid System
The lymphoid system contains cells, tissues, and organs that protect the body from pathogens, foreign substances, and elimination of diseased cells.
Lymph nodes are major sites for lymphocytes and are distributed along lymphatic vessels. They filter lymph passing through the nodes to remove pathogens, debris, and cancer cells.
Lymphatic capillaries are thin-walled vessels the drain and process extracellular tissue fluids. The fluid is mostly plasma that has leaked out of blood vessels into the interstitial space of tissues.
An example of lymphatic capillaries draining fluid from a tissue is the small intestine. The interior is covered by projections (villi) that contain lymphatic capillaries (lacteals).
The spleen is an encapsulated organ involved in the filtration of blood and immunologically monitors blood.