Question

Question 1 (2 points) All of the following are part of the immune system EXCEPT O a) bone marrow b) feet c) lymph nodes d) spleen O e) thymus

Answer 1

b) Feet

Immune system is a network of cells, organs and proteins, which functions to protect the body. Some of the important organs involved in providing immunity are- bone marrow, lymph nodes, spleen, thymus, etc.

Bone marrow is the site of blood production. All types of blood cells, including B lymphocytes and T lymphocytes, originate in the bone marrow. The bone marrow is also the site of maturation of B lymphocytes. The mature B lymphocytes activate and proliferate in presence of foreign pathogen, and produce antibodies and memory cells, which help to eliminate the foreign particles out of the body.

The T lymphocytes, after being made in the bone marrow, move to the thymus, for maturation. Mature T cells recognize foreign antigen, associated with the MHC, and proliferate into effector cells and memory cells, which eliminates the pathogen out of the body, and also provide immunity against future infections.

The lymph nodes function like a filter in the immune system. Lymph flowing through the lymph nodes, carry foreign pathogen, from all over the body. These foreign particles are trapped and destroyed by the immune cells present within the nodes. Two important immune cells present in the lymph nodes are macrophages, (which carry out engulfment of the pathogen) and lymphocytes.

Spleen also acts as a filter and clears the foreign particles present in the blood. The leukocytes present within the red pulp of the spleen provides adaptive immunity. The white pulp produces lymphocytes and antibodies, that function in the destruction of the pathogen. People having their spleen removed, are at a higher risk of developing infections.

Feet are not a part of the immune system. Their main function is to support the body and help in locomotion.