The lymphatic system is similar to the circulatory system. Lymph, like blood, flows through an elaborate route of vessels. In addition to lymphatic vessels, the lymphatic system consists of lymph nodes, lymph, and the spleen. Unlike the circulatory system, the lymphatic vessels do not form a closed circuit. Lymph flows only once through the vessels before draining into the general blood circulation. This system is a filtering mechanism for microorganisms and serves as a protective device against foreign invaders, such as cancer.
The immune system is the armed forces division of the body. Ready to attack at moment's notice, the immune system defends us against the major enemies of the body: microorganisms, foreign transplanted tissue cells, and our own cells that have turned malignant.
The most numerous cells of the immune systems are the lymphocytes. These cells circulate in the body's fluids seeking invading organisms and destroying them with powerful lymphotoxins, lymphokines, or antibodies.
Phagocytes, another large group of immune system cells, assist with the destruction of foreign invaders by a process known as phagocytosis. Neutrophils, monocytes, and connective tissue cells called macrophages use this process to surround unwanted microorganisms, ingest and digest them, and render them harmless to the body.
Another weapon that the immune system possesses is complement. Normally a group of inactive enzymes present in the blood, complement can be activated to kill invading cells by drilling holes in their cytoplasmic membranes allowing fluid to enter the cell until it bursts.
Structure and Function of the Body Prepared by Linda Swisher.
No comments:
Post a Comment