cell recognition and immunity Flashcards
what can our immune system identify by their organisms
-pathogens
-cell surface structures
-cellls from other organisms of the same species
-cancerous cells
-toxins
main defence mechanisms of the body
non specific and specific
non specific response
response is immediate and the same for all pathogens
specific response
response is slower and specific to each pathogen
non specific response methods
primary method eg skin
secondary methods eg phagocytosis
specific response methods
-cell mediate response - t lymphocytes
humoral response - b lymphocytes
two immune system
non specific - all animals
specific-only vertebrates
what iOS the immune system
complex networks of cells tissue and organs and molecules
cells of immune system
white blood cells
inflammation
1)injury cut or graze
2)damaged white blood cells and mast cells from connective tissue releases histamines
3)dilation of arterioles in the area
4)increases blood flow in capillaries and capillary cells separate slightly
5)plasma white blood cells and antibodies leak into tissues causing oedema
6)white blood cells can destroy microbes
phagocytosis
1)neutrophils arrive first and engulf 5-20 bacteria but then die
2)macrophages arrive and destroy up to 100 bacteria
phagocytosis stages
1)chemotaxis
2)Adhesion
3)ingestion and intracellular digestion
4)disposal
chemotaxis
actively seek foreign antigens stimulated by chemicals released by the pathogen or lymphocytes
adhesion
firm connection between phagocytes membrane and the antigen
ingestion and intracellular digestion
pathogen engulfed and surrounded by a membrane e lines vacuole where lysosomes containing enzymes break it down
disposal
the parts that cannot be used in metabolism are ejected by exocytosis
specific immune repose - clonal expansion
-specific lymphocytes are not produced in response to an infection they already excst
-there are so many different types there is high probability that one of these will have a protein on surface that is complementary to an antigen
-when infection occurs the one type of cell that recognises the antigen will divide to build up the numbers of that particular type
apotosis
cell death
when lymphocytes recognise and rwespsond to cells in our own body
-in the foetus lymphocytes rarely come into contact with pathogens so collude exclusively with self cells
-some of the receptors fits those pf the body cells these lymphocytes are then suppressed
-this leaves only lymphocytes that might recognise non-self antigens
t lymphocytes
mature in thymus gland
-cell mediated immune its ie. immunity requiring the cell to be present
-have receptor proteins that can detect antigens and form antigen receptors complexes
-helped T cells th
cytoxic T cells tc
-antigen recognition site binds to antigens
b lymphocytes
form and mature in bone marrow
activTION of t helper cell
1)bacterium with antigen on surface
2)bacterium engulfed by macrophage
3)macrophage presents antigens on major hustocompatability complexes becomes an antigen presenting cell
Explain why the secondary immune response is much more rapid than the primary one
Because of the production of memory cells the secondary response is much more faster than the primary one . The memory cells differentiate into plasma b cells rapidly to produce much more antibodies at a faster rate against the pathogens .
Primary immune response - B cell clonal selection
B cells bind to antigens the antigen enters by endocytosis and then is presented on surface of cell it has become an antigen presenting cell
