advertisement
23 April 2007

The first line of defense

The immune system is a complex of organs - all of which work together to clear infection from the body.

0
The immune system is a complex of organs - highly specialised cells and even a circulatory system separate from blood vessels - all of which work together to clear infection from the body.

The organs of the immune system, positioned throughout the body, are called lymphoid organs. The word "lymph" in Greek means a pure, clear stream - an appropriate description considering its appearance and purpose.

Lymphatic vessels and lymph nodes are the parts of the special circulatory system that carries lymph, a transparent fluid containing white blood cells, chiefly lymphocytes.

Lymph bathes the tissues of the body, and the lymphatic vessels collect and move it eventually back into the blood circulation. Lymph nodes dot the network of lymphatic vessels and provide meeting grounds for the immune system cells that defend against invaders. The spleen, at the upper left of the abdomen, is also a staging ground and a place where immune system cells confront foreign microbes.

Pockets of lymphoid tissue are in many other locations throughout the body, such as the bone marrow and thymus. Tonsils, adenoids, Peyer's patches, and the appendix are also lymphoid tissues.

Both immune cells and foreign molecules enter the lymph nodes via blood vessels or lymphatic vessels. All immune cells exit the lymphatic system and eventually return to the bloodstream. Once in the bloodstream, lymphocytes are transported to tissues throughout the body, where they act as sentries on the lookout for foreign antigens.

(Source: National Institutes of Health)

 
NEXT ON HEALTH24X
advertisement

Read Health24’s Comments Policy

Comment on this story
0 comments
Comments have been closed for this article.

Live healthier

Hello? »

SEE: Interesting facts about hearing loss Earworms: Let it go Is it bad to sleep with earplugs all the time?

SEE: Do women hear better than men?

The reason why men often appear not to be listening could be because they actually can't hear you.

Confident smile? »

Acidic drinks can harm your kids' smiles The facts on bleaching your teeth Am I taking good care of my teeth?

Why are my teeth stained?

We know the rules – brush your teeth twice a day and floss to keep them healthy. But, have you ever wondered what causes those stains that sometimes appear?