Question

list the cellular and chemical systems in the 3rd line of defense.

Answer 1

There are 3 lines of defense in our body against any foreign pathogen.

1st line of defense is Physiologic and Anatomical Barriers, i. e. Skin, Mucous membranes, temperature etc. This is non-specific innate immunity.

2nd line of defense is non-specific resistance. In this process foreign materials destroyed in generalized way .By several processes like phagocytosis, inflammation, fever. This is innate immunity.

3rd line of defense is Specific resistance. It is acquired or adaptive immunity. This system mainly relies on antigen.

There are mainly two part of this acquired immune response: Cell mediated and Humoral.

Cells involved in Cell mediated immune response: T Lymphocytes(T helper, T cytotoxic) and B Lymphocytes (memory B cells, effector B cell), Antigen Presenting Cell.Humoral immunity is the secretion of antibodies from plasma cells, complement proteins from immune cells.

When an foreign pathogen enters and recognized by the macrophages, T cells gets activated .

These T cells secretes specific interleukin which further activates B cells and T_cytotoxic cells.

B cells proliferate and forms plasma cell and memory B cell. plasma cells secrete antibodies.

On the other hand, T_cytotoxic cells secretes cytokines, which causes apoptosis to infected cells.

Memory B cells are the memory of the immune system. They protect the individual from further attack by the same antigen.