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31.3 Immune Responses KEY CONCEPT The immune system has many responses to pathogens and foreign cells. 31.3 Immune Responses Many body systems work to produce nonspecific responses. • Nonspecific responses are those that are the same everytime. • In inflammation, blood vessels become leaky. capillary wall – white blood cells move extracellular space toward infection and damaged tissue – characterized by swelling, redness, and pain Another Example: Fever white blood cell 31.3 Immune Responses • In fever, body temperature increases. – Low fevers stimulate white blood cells to mature. – High fevers can cause seizure, brain damage, and even death. 31.3 Immune Responses 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. antigens virus 31.3 Immune Responses • There are two specific immune responses. – Cellular immunity uses T cells to destroy infected body cells. pathogen antigens antigens T cell receptors memory T cells activated T cells 31.3 Immune Responses • There are two specific immune responses. – Humoral immunity uses B cells to produce antibodies. B cell pathogen antibodies T cell memory B cells activated B cells 31.3 Immune Responses • Both responses produce memory cells. B cell T cell – specialized T and B cells – Provide(give) acquired (active) immunity 31.3 Immune Responses The immune system rejects foreign tissues. • Tissue rejection occurs in organ or tissue transplants. • Tissue rejection occurs when white blood cells recognize donor tissue as foreign and attack and destroy the tissue.