KEY CONCEPT The immune system has many responses to pathogens and foreign cells.

The job of the immune systems is to fight off pathogens & infections. Skin is a physical barrier to infection. Mucous Membranes trap pathogens entering the body.

Two nonspecific responses. Inflammation - blood vessels become leaky. characterized by swelling, redness, and pain Fever - body temperature increases Low fevers stimulate white blood cells to mature.

Cells of the immune system produce SPECIFIC RESPONSES Specific Immune response: Antigens are surface proteins on pathogens. Each pathogen has a different antigen. antigens

White Blood Cells attack infections inside the body. Phagocytes engulf and destroy pathogens. T cells destroy infected cells. B cells produce antibodies. Antibodies make pathogens ineffective.

There are 2 specific immune responses. pathogen antigens T cell receptors activated T cells memory T cells Cellular Immunity T-cells to destroy infected body cells.

Antibody Immunity B-cells produce antibodies. memory B cells activated B cells antibodies B cell T cell pathogen

Both responses produce memory cells

Vaccines Allow person to acquire immunity without contracting disease Contain the antigen of a weakened pathogen Does not cure a person who is sick

Vaccination provides immunity. Antigens in a vaccine trigger an immune response, and memory B cells are made. 1 memory B cells stimulates a specific immune response causes memory B & T cells to be produced allows immune system to respond quickly to infection next time has such a fast response, a person will not get sick A memory B cell is stimulated when the real pathogen binds to it. 2 The B cell quickly activates and makes antibodies that fight the pathogens before you get sick. 3