31.3 IMMUNE SYSTEM

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

Nonspecific Responses.  Nonspecific responses are the same for every pathogen.  In inflammation, blood vessels become leaky.  white blood cells move toward infection and damaged tissue –characterized by swelling, redness, and pain capillary wall extracellular space white blood cell

 In fever, body temperature increases. –High fevers can cause seizure, brain damage, and even death. –Low fevers stimulate white blood cells to mature.

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

pathogen antigens T cell receptors activated T cells antigens memory T cells  There are two specific immune responses. –1. Cellular immunity uses T cells to destroy infected body cells.

–2. Humoral immunity uses B cells to produce antibodies. memory B cells activated B cells antibodies B cell T cell pathogen

 Both responses produce memory cells. –specialized T and B cells –provide acquired (active) immunity B cell T cell

The immune system rejects foreign tissues.  Tissue rejection is the result of an immune response.  Immune system makes antibodies against the donor ’ s tissue