KEY CONCEPT The immune systems consists of organs, cells, and molecules that fight infections.

Many body systems protect you from pathogens. The immune system is the body system that fights off infection and pathogens. Many other tissues and systems help the immune system. Skin is a physical barrier to infection. Mucous membranes trap pathogens entering the body. The circulatory system transports immune cells.

Cells and proteins fight the body’s infections. White blood cells attack infections inside the body. Phagocytes engulf and destroy pathogens. T cells destroy infected cells. B cells produce antibodies.

Immunity prevents a person from getting sick from a pathogen. In all immunity, pathogens are destroyed before you get sick. Passive immunity occurs without an immune response. mother’s milk genetics Active immunity occurs after a specific immune response

Nonspecific responses are the same for every pathogen. Many body systems work to produce nonspecific responses (generic way to fight-off intruders). Nonspecific responses are the same for every pathogen. In inflammation, blood vessels become leaky. white blood cells move toward infection and damaged tissue capillary wall extracellular space white blood cell characterized by swelling, redness, and pain

In fever, body temperature increases. Low fevers stimulate white blood cells to mature. High fevers can cause seizure, brain damage, and even death (THINK BACK TO ENZYMES!)

Cells of the immune system produce specific responses. Specific immune responses begin with the detection of antigens. Antigens are surface proteins on pathogens. Each pathogen has a different antigen. virus antigens

This is who vaccines work After you have come into contact with a pathogen memory cells are created. B cell T cell This is who vaccines work

The immune system rejects foreign tissues. Tissue rejection occurs in organ or tissue transplants. Tissue rejection is the result of an immune response. immune system detects protein markers on the donor tissue makes antibodies against the donor’s tissue