Specific Immune Response Flashcards
Three types of T cells
Helper, killer and memory
Role of t helper cells
Release substances to activate B cells and become cells capable of producing antibodies, T killer cells and macrophages
Role of t killer cells
Attach to antigens recognises as foreign on a pathogen-infected cell and kill the cell
What are T cells
Type of WBC with surface covered with receptors which bind to antigens displayed by antigen-presenting cells eg macrophages
-each T cell has dif shaped receptor
How does T cell become activated
When the receptor on the surface of a T cell meets a complementary antigen and it binds to it, activated cell then divides to produce clones of itself
What are B cells
-type of WBC, covered with proteins called antibodies which bind to antigens to form antigen-antibody complex
-each had different shaped antibody on surface
How does B cell become activated
When the antibody of surface of B cell meets a complementary antigen it binds to it and this together with substances released from the T cell activated it
-this divides by mitosis into plasma cells (B effector cells) and B memory cells
What are lymphocytes
WBCs that help to defend the body against specific diseases, circulate in blood and lymph and gather at site of infection, main types are B cells and T cells
What are B lymphocytes
-produced and mature in bone marrow
-each has one specific antigen receptor on its surface and is activated when it’s receptor binds to an antigen with complementary shape
-once activated it secretes antibodies in response to antigen which bind to antigens and act as labels allowing phagocytes to recognise and destroy the cell
What causes the different shape of bonding site of antibody
Amino acid sequences are different
Process of how antibody attaches to antigen and allows phagocytes to identify them
-activated B cell produced antibodies which bind to antigens on bacteria surface and labels them
-antibody binds to antibody receptor on macrophage
-macrophage engulfs antibodies and bacterium, lysosomes fuse with vacuole which releases digestive enzymes that destroy the bacterium
Process of how T lymphocytes are produced, mature and activated
-immature T cells produced by division of stem cells in bone marrow and move to thymus via blood
-mature in thymus, leave thymus in blood and move to lymph nodes and spleen
-as lymph fluid passes through a lymph node/blood passes through spleen T cells are activated by any pathogens present
How are T helper cells activated
When it’s CD4 receptors bind to complementary antigen on the surface of the antigen-presenting cells. Will then divide to produce a clone of active t helper cell and a clone of t memory cells(remains for months/years in body)
Outline cell mediated response
-phagocytosis takes place
-WBCs act as antigen presenting cell presenting antigens of pathogen they broke down
-T helper cells with correct receptor for specific antigen bind to antigen presenting cell
-T helper cell activated and undergo mitosis to produce clones
-T helper cell produce cytokines: activates B cells and stimulates them to divide by mitosis, activate T killer cells, trigger phagocytes to increase rate of phagocytosis, form clones of T memory cells which can rapidly differentiate into T killer cells if reinfected with same pathogen and remains for months/years in body
How do T killer cells destroy cells
-identify abnormal/virally infected cells
-T killer cell with complementary receptors bind to antigen presented on body cell and divide to form an active clone which is stimulated by cytokines from T helper cells
-T killer cells release enzyme perforin which created pores in membrane of infected cell enabling ions and water to flow into cell which swells and bursts(lysis) and pathogens within cell released
