Answer:
Primary lymphoid organs are where lymphocytes are formed and mature. They provide an environment for stem cells to divide and mature into B- and T- cells. There are two primary lymphoid organs: the red bone marrow and the thymus gland.
Secondary lymphoid organs are where mature lymphocytes interact with antigens. They are responsible for the adaptive immune response, which is the body's ability to remember and respond to specific antigens. Examples of secondary lymphoid organs include lymph nodes, the spleen, and the tonsils.
Granulocytes are white blood cells that have granules in their cytoplasm. They are the first line of defense against infection. Neutrophils are the most common type of granulocyte. They are phagocytic, meaning they can engulf and destroy bacteria. Eosinophils are involved in allergic reactions and parasitic infections.
- Neutrophils: These are the most common type of white blood cell, and they play a major role in fighting infections.
- Eosinophils: These cells help to fight parasites and allergic reactions.
Agranulocytes do not have granules in their cytoplasm. Lymphocytes are a type of agranulocyte that are involved in the adaptive immune response. They can be divided into B cells and T cells. B cells produce antibodies, which are proteins that can bind to and neutralize bacteria and viruses. T cells help to regulate the immune response and kill infected cells.
- Lymphocytes: These cells are involved in the immune system, and they produce antibodies.
- Monocytes: These cells mature into macrophages, which are large cells that engulf and destroy bacteria and other foreign substances.
Fixed leukocytes are white blood cells that are permanently located in tissues. Macrophages are a type of fixed leukocyte that phagocytose foreign particles and debris. Dendritic cells are a type of fixed leukocyte that present antigens to lymphocytes.
- Dendritic cells: These cells are found in the skin and other tissues, and they help to present antigens to lymphocytes.
- Mast cells: These cells are found in the tissues, and they release histamine and other chemicals in response to allergens or other triggers.