Question

Name the primary and secondary lymphoid organ.

Answer 1

Hint: Lymphoid system in the vertebrates is the part of the circulatory system and the immune system. The lymphatic system consists of lymph vessels, lymphoid organs and tissues which circulate lymph.

Complete step by step answer:
The lymph system is the part of the circulatory system and immune system. Lymph fluid flows in the lymphatic vessels. The main function of this system is immune defence. Lymph organs are composed of lymphatic tissues and are the site of lymphocyte production and activation. The lymph organs are of two types-
The primary lymphoid organs generate lymphocytes from immature progenitor cells. They are the organs where the stem cells divide.
Bone marrow- It is responsible for making T-cells and B-cells. These cells are important for the immune system.
Thymus- Thymus is most active during neonatal and pre-adolescent periods. It provides an inductive environment for the maturation of T-cells.
The secondary lymphoid organs are important sites for adaptive immune response. It is activated by the antigens.
Spleen- It synthesises antibodies. It produces immune cells to fight antigens. They produce blood cells during fetal life. They also remove aged blood cells.
Lymph nodes -These are the collection of lymph tissues. Its clusters are found in underarms, neck etc. It provides an environment for the antigens to interact with the lymphocytes.

Note:
Lymphatic organs are the site of production and maturation of immune cells. They are the site of adaptive immune response. The primary and secondary lymph organs work together and protect the body from foreign antigen.