Question

Identify A and B in the diagram below. Explain their role in the immune system of the body.

Answer 1

A: Lymph nodes.

B: Thymus

Role of Lymph nodes in the immune system of the body:

1. The lymph nodes are small, solid structures located at different points along the lymphatic system.
2. Lymph nodes serve to trap the microorganisms or other antigens that happen to get into the lymph and tissue fluid.
3. Antigens trapped in the lymph nodes are responsible for the activation of lymphocytes present there and cause the immune response. 

Role of Thymus in the immune system of the body:

1. The thymus is a lobed organ located near the heart and beneath the breastbone.
2. The thymus is quite large at the time of birth but keeps reducing in size with age, and by the time puberty is attained, it reduces to a very small size.
3. Both bone marrow and thymus provide microenvironments for the development and maturation of T-lymphocytes.