4.2. Specific Cellular Defences Flashcards
What are antigens?
Proteins that trigger immune responses. Antigens associated with certain pathogens trigger specific immune responses.
What is immune surveillance?
Our white blood cells monitoring our tissue. Certain white blood cells produce cytokines when tissue is damaged. More white blood cells then accumulate at the area and move between infected tissue cells. Some of these white blood cells are phagocytes and lymphocytes.
What is clonal selection theory?
Lymphocytes have proteins on their surface which can tell apart foreign and self antigens. Lymphocytes that recognise our own antigens die during embryonic development.
One lymphocytes receptor is specific to one antigen. When this lymphocyte matches with its antigen it binds with the antigen. This lymphocytes then divides multiple times creating clones of itself. These clones fight the infection and some stay after the infection is gone as memory cells.
What are the two types of T-Lymphocyte?
T lymphocytes that induce apoptosis: when phagocytes destroy a pathogen, there are antigenic fragments on that phagocyte. Some T cells recognise these fragments and bind to them. These T cells then produce clones. Some of these clones move to the original infection site presenting the same antigenic fragments. This causes them to undergo apoptosis.
T lymphocytes that secrete cytokines: these cells are activated by specific antigen presence. They secrete cytokines which cause B lymphocytes to divide.
What is the function of B lymphocytes?
Cytokines secreted by T cells cause specific B cells to divide. B clones secrete molecules called antibodies which are release in huge quantities into the bloodstream and lymph. They are then carried to the infected area where they bind to the antigens and inactivate the pathogens, or make them vulnerable to phagocytes.
What is autoimmune disease?
When our immune system fails and our T lymphocytes attack our own antigens. This causes autoimmune disorders.
What is an allergy?
When B lymphocytes become hypersensitive to harmless antigens. The immune response to these antigens is an allergic reaction.
What is immunological memory?
Due to some clones of T cells staying after an infection has been stopped, a second exposure to this antigen causes a faster response. The person is immune to this now and may not even notice they were exposed to this antigen.
