Transcript 31.3 Immune Responses

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 the same for every pathogen.
• In inflammation, blood vessels become leaky.
capillary wall
– white blood cells move extracellular
space
toward infection and
damaged tissue
– characterized by
white blood cell
swelling, redness, and
pain
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 acquired (active) immunity
31.3 Immune Responses
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