6.3 Response to Infection Flashcards
Physical Barriers
Skin- Physical Barrier consisting of keratin
Stomach Acid- kills bacteria
Skin Flora- Competes with pathogens for food + space
Inflammation
Histamines caused by WBC cause vasodilation
this increases blood to infected area + increases permeability of blood vessels
WBC + plasma leak out into infected tissue + destroy pathogen
Fever
Hypothalamus increases body temp
decreases speed of pathogen reproduction
increases speed of immune response
Phagocytosis
WBC engulfs + destroys pathogens
fuses with bacteria + encloses it in a phagosome with a lysosome
Specific Response
Specific to 1 pathogen only
Relies on lymphocytes produced in the bone marrow
B cells
mature in the bone marrow
Involved in the humoral response
T cells
Move from bone marrow to the thymus gland where they mature
Involved in the cell mediated response
Cell Mediated Response
1) Pathogen invades a host cell
2) Host cell displays antigens of pathogen on its MHC + becomes an APC
3) T killer cell with complementary receptors bind to APC
4) Cytokines secreted by T helper cells stimulate T killer cells to divide by mitosis
5) T killer cells divide to form active T killer cells + T killer memory cells
6) Active T killer cells bind to APC + secrete chemicals
pores form in the cell membrane
cell dies
Humoral Response ( T Helper Activation)
1) Bacteria is engulfed by macrophage
2) Macrophage acts as an APC + presents antigens on its MHC
3) APC binds to T helper cells with complementary receptors
4) T helper cell divides by mitosis to form T memory + active T helper cells
Humoral Response (Effector Stage)
1) Antigens from APC bind to complementary antibodies on B cells
taken in by endocytosis
2) B cell acts as an APC + presents antigens on its MHC
3) Activated T helper cell binds to the APC
produces cytokines
4) Cytokines stimulate the B cell to divide by mitosis + form B memory + effector cells
5) B effector cells differenciate into plasma cells
6) Plasma cells synthesise antibodies
7 T suppressor cells stop the immune response
Effects of Antibodies
Agglutination
Lysis
Opsonisation
Neutralisation
Agglutination
Microbes clump together
Makes phagocytosis easier
Lysis
Bursting of Cells
Opsonisation
Antibodies coat microbes + mark them for phagocytes
Neutralisation
Soluble toxins are made insoluble
Active Immunity
the production of antibodies by immune system in response to an antigen
Passive Immunity
Introduction of antibodies from another person/ animal
Natural Active Immunity
Being exposed to an antigen
Contracting the disease
Natural Passive Immunity
Crossing of mother’s antibodies through the placenta
Active Passive Immunity
Acquired through vaccinations
Active Passive Immunity
Antibodies are infected into body
Herd Immunity
Enough people have to be vaccinated to make transmission very unlikely
