ANATOMY

Detailed explanation-1: -The main components of the immune system are the thymus, spleen, Lymph Nodes, bone marrow and white blood cells. A brain is not involved in elicitation of immune response but regulates the function of the whole body.

Detailed explanation-2: -Organs and tissues important to the proper functioning of the immune system include the thymus and bone marrow, lymph nodes and vessels, spleen, and skin.

Detailed explanation-3: -Answer and Explanation: The option that is not part of the innate immune system is b. Antibodies in the blood. Antibodies are part of the adaptive immune response that are produced by plasma B cells.

Detailed explanation-4: -Humans have three types of immunity-innate, adaptive, and passive: Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. For example, the skin acts as a barrier to block germs from entering the body.