disease + defences in animals Flashcards
what are the 7 main non-specific defences to disease in animals
- hand washing
- eyelashes + tears
- nose + body hair
- earwax
- ciliated epithelium
- stomach acid
- phagocytes
how does hand washing protect against disease
it removes bacteria and other microorganisms form skins surface, preventing entry + infection
also prevents spread among humans
how do eyelashes + tears protect against disease
eyelashes are a physical barrier defence preventing pathogens entering or settling on cornea
tears contain lysosomes with hydrolytic enzymes so they can kill bacteria - makes tears antiseptic
how does nose + body hair protect against disease
hair traps large pathogens and prevents them from entering the body
hairs also produce sebum - oil that stops bacteria reproducing
micro biotic flora in these areas can fight off pathogens
how does earwax protect against disease
it can trap pathogens
small hairs can then move earwax out of the ear into the outer area where it can be cleaned
how does ciliated epithelium protect against disease
found alongside goblet cells which secrete mucus that traps pathogens small enough to pass through nose hair
cilia beat to waft away mucus so it can be disposed of, e.g. by stomach acids
how does stomach acid protect against disease
helpful bacteria on stomach lining can fight off pathogen
HCl is very acidic + stops microorganisms from settling as most are unable to survive
what are the 2 types of phagocyte
neutrophils and macrophages
outline the process of phagocytosis in neutrophils
1- cytokines, histamines and antibodies attract phagocyte to the area
2- cell surface membrane extends around the pathogens and engulfs it via endocytosis - requires ATP
3- a phagosome is formed and lysosomes containing hydrolytic enzymes fuse with the phagosome - forms a phagolysosome
4- hydrolytic enzymes digest + break down pathogen
5- toxic waste products are absorbed by neutrophil
why are neutrophils short lived cells
they absorb toxic waste products from pathogen break down which ends up killing it
- pus is a sign of dead neutrophils
how do phagocytes protect against disease
they kill pathogens through phagocytosis
outline the process of phagocytosis in macrophages
1- cytokines, histamines and antibodies attract phagocyte to the area
2- cell surface membrane extends around the pathogens and engulfs it via endocytosis - requires ATP
3- a phagosome is formed and lysosomes containing hydrolytic enzymes fuse with the phagosome - forms a phagolysosome
4- the hydrolytic enzymes cut up the pathogen
5- using glycoproteins on cell surface membrane the antigens from the pathogen are attached on the outside of the macrophage - it becomes an antigen presenting cell
what is a macrophage with foreign antigens attached to it called
antigen presenting cell
what is formed when a foreign antigen attaches to the macrophage cell surface membrane
major histocompatibility complex
how does the activity of a macrophage enhance the body’s immune response
major histocompatibility complexes can be recognised by T-lymphocytes
what type of immunity is achieved by T-cells
cell mediated immunity
where are T-cells made + found
made in bone marrow and differentiate in thymus gland
outline the mechanism of T-lymphocytes in the immune response
1- an antigen presenting cell is formed in the body’s primary response
2- a T-helper cell which matching receptors binds to the APC and becomes activated - clonal selection
3- the T-helper cell undergoes mitosis - clonal expansion
4- it also releases interleukins
5- the cloned T-cells can now differentiate into many types of cell
interleukins definition
a type of cytokine
these can trigger phagocytes to increase the rate of phagocytosis and stimulates B-cells to undergo clonal expansion
what 4 types of cells can T-cells differentiate into
T-helper
T-killer
T-regulator
T-memory
what do T-helper cells do
they can release cytokines and interleukins
this helps attract macrophages / phagocytes and also helps B-cells divide
what do T-killer cells do
they attach to foreign antigens on infected body cells/cancers and secrete chemicals that kill cells
- these are perforins, which destroy cell surface membrane and cause the cell to burst/die
what do T-regulator cells do
these regulate the immune response by preventing attacked on uninfected cells and shutting down the process when pathogen is cleared, so no resources are wasted
what do T-memory cells do
these are long lived cells which remain in blood
they can rapidly divide into T-killer cells - secondary immune response
if the body is infected with the same pathogen again clonal selection is much faster due to these cells
what type of immunity is achieved by B-cells
humoral immunity