Question

what happen in lymphoid organs with respect to immunity.

Answer 1

Lymphoid organs are of two types − primary lymphoid organs and secondary lymphoid organs.

• Primary lymphoid organs consist of bone marrow and thymus. Here, immature lymphocytes are differentiated to form antigen-sensitive lymphocytes.

  • Bone marrow − Here, all blood cells including lymphocytes are produced.

  • Thymus − It is responsible for maturation of T-lymphocytes. This lobed organ is situated near the heart and keeps on reducing in size as the age increases.

• Secondary lymphoid organs − Lymphocytes migrate here after attaining maturity. It includes spleen, lymph nodes tonsils, Peyer’s patches, and appendix.

  • Spleen − Large bean-shaped organ containing lymphocytes and phagocytes, which acts as a filter for blood

  • Lymph nodes − Located at different points throughout the immune system, they trap the antigens present in lymph or tissue fluid, and these antigens cause activation of lymphocytes and generation of immune response.

• MALT (Mucosal-associated lymphoid tissue) − Lines major tracts (respiratory, digestive, urogenital, etc); constitutes 50% of lymphoid tissue in body