Immune Response Flashcards
The immune response to a virus.
A, A virus invades the body through a break in the skin or another portal of entry. The virus must make its way inside a cell in order to replicate itself.
B, A macrophage recognizes the antigens on the surface of the virus. The macrophage digests the virus and displays pieces of the virus (antigens) on its surface.
C, T helper cells recognize the antigen displayed and bind to the macrophage. This binding stimulates the production of cytokines (interleukin-1 [IL-1] and tumour necrosis factor [TNF]) by the macrophage and interleukin-2 (IL-2) and γ-interferon (γ-IFN) by the T helper cells. These cytokines are intercellular messengers that provide communication among the cells.
D, IL-2 instructs other T helper cells and T cytotoxic cells to proliferate (multiply). T helper cells release cytokines, causing B cells to multiply and produce antibodies.
E, T cytotoxic cells and natural killer cells destroy infected body cells.
F, The antibodies bind to the virus and mark it for macrophage destruction.
G, Once the virus is gone, activated T and B cells are turned off by suppressor T cells. Memory B and T cells remain behind to respond quickly if the same virus attacks again.
Lymphoid Organs
The central lymphoid organs are the thymus gland and bone marrow.
The peripheral lymphoid organs are the lymph nodes; tonsils; spleen; and gut-, genital-, bronchial-, and skin-associated lymphoid tissues (
