Topic 2 - C : Cells and the immune system Flashcards
Pathogen
organism that causes disease
Toxins
poison
molecules
antigens
molecules that generate immune response
Phagocytosis
-Phagocyte recognises foreign antigens on pathogen
- Phagocyte engulfs pathogen
- Pathogen contained in phagosome
-lysosomes release hydrolytic enzymes to break down pathogen
- exocytosis
T-cells
Type of white blood cell
receptor proteins on surface which bind to complementary antigens presented by phagocytes. This activates T-cells
T helper cells activate B cells and activate phagocytes
Cytotoxic t-cells kill abnormal and foreign cells
B-cells
Type of white blood cells
covered with antibodies - proteins that bind to antigens to form an antigen-antibody complex
Each b-cell has a different shaped antibody on its membrane, so different ones bind to different shaped antigens
When antibody on surface of b-cell meets complementary shaped antigen, it binds to it.
this activates b cells to divide into plasma cells
Antibody production
Plasma cell = B cell
they secrete antibodies specific to antigens (monoclonal antibodies)
bind to form lots of antigen-antibody complexes.
agglutination
antibody has two binding sites, so can bind to two pathogens at same time meaning pathogens become clumped together.
phagocytes then attach to the antibodies
cellular response
t cells and other immune system cells that they interact with (phagocyte)
Humoral
B cells
clonal selection
production of monoclonal antibodies
what is the point of cellular and humoral response
remove pathogens from the body
Primary response
not enough b cells to make the antibody needed to bind to it
once there are enough of the right antibody to overcome the infection, meanwhile showing symptoms of the disease
after being exposed to antigen, B-cells and T-cells produce memory cells which remain in the body for a long time
Secondary response
immune system will produce a response a lot quicker
clonal selection faster
memory b cells are activated and divide into plasma cells that produce the right antibody to the antigen
memory t-cells are activated and divide into the correct type of T-cells to kill the antigen
active immunity
natural - when you become immune after catching a disease
artificial - when you become immune after you’ve been given a vaccination exposing you to a harmless dose of antigen
passive immunity
natural - baby becomes immune to an antigen it receives from its mother
artificial - immunity after injection with antibodies
