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
where are B-cells made + found
made and matured in bone marrow
outline the mechanism of B-lymphocytes in the immune response
1- pathogens/antigens enter humour and are engulfed
2- B-lymphocytes digest pathogen and presents antigens - becomes an antigen presenting cells
3- T-helper cells attach to APC causing clonal selection
4- T-helper cells release interleukins which activates B-cells to divide - this is clonal expansion
5- B-cells divide into many types of cell
what 2 types of cells can B-cells differentiate into
plasma cells
B-memory cells
what do plasma cells do
they make and secrete specific antibodies into the blood, lymph, lining of lungs and gut
in the body’s first encounter with the pathogen it takes some time for the correct plasma cells and antibodies to be produced, so the pathogen is able to reproduce - so body will show symptoms
what do B-memory cells do
they are long lived cells which remain in blood and can rapidly divide into plasma cells and produce antibodies - secondary immune response
often in these cases they can destroy pathogens before symptoms develop
what are antibodies
Y shaped proteins produced by plasma cells that fight off pathogens - specific immune response
what kind of protein are antibodies
globular proteins with quaternary structures - made of 2 heavy chains + 2 light chains
name the main structural features of an antibody
antigen binding sites
disulphide bridges
2 light polypeptide chains
2 heavy polypeptide chains
variable region
constant region
hinge region
what is the structure + function of the antigen binding sites
there are 2 located on the tips of the Y shape - these are complementary to the antigens, so varies between antibodies
they bind to the antigens on a pathogen and help to destroy them
what is the function of the disulphide bridges
these hold the polypeptide chains together, maintaining the Y shape
what is the structure + function of the variable region
these contain the amino acid sequence that is unique for each antibody / complementary for each pathogen
it is where the antigen binding sites are located
what is the structure + function of the constant region
these do not vary within a class of antibodies but can vary between classes - they determine the mechanism used to destroy pathogens
- there are 5 classes, all with different roles
what is the structure + function of the hinge region
this is located at the Y intersection - it gives flexibility to the antibody allowing the antigen binding sites to be placed at different angles when binding, and also allows antibodies to catch onto more than 1 binding site
what are 3 functions of antibodies
opsonins
agglutinins
antitoxins
how do antibodies act as opsonins
opsonins facilitate the recognition and destruction of pathogens by immune cells by binding to the surface of pathogens in order to aid in its recognition + destruction
antibodies do this by binding to antigens on pathogens, as they are complementary
how do antibodies act as agglutinins
agglutinins bind to the antigen, causing them to crosslink and form a lattice like structure, trapping cells together so they are more easily engulfed by white blood cells
antibodies are capable of clumping together pathogens as they have 2 binding sites
how do antibodies act as antitoxins
antitoxins can neutralise the harmful effects of toxins by binding to them and so preventing them from binding to target cells
antibodies are produced in response to the presence of toxins produce by antibodies and can bind to them to neutralise them - they are also used in the treatment of some infections due to this, as they can help with patient recovery
how are toxins harmful to the body
they can cause tissue damage, impair organ function, and even cause death
autoimmune disease definition
conditions caused when immune responses occur against naturally occurring body cells
give 2 examples of autoimmune diseases
lupus
rheumatoid arthritis
why is treating lupus difficult
- lupus is a chronic disease with no cure
- treatments depend on individual symptoms, it can prevent flares or improve other symptoms of lupus
- diagnosis is difficult as it is often mistaken for other diseases and symptoms vary between individuals
what areas are often affected by lupus
as lupus is a chronic disease, this means long term destruction is caused
- affected areas include joints, kidneys, heart, lungs, skin
what areas are often affected by rheumatoid arthiritis
solely affects joints, usually begins in the fingers and hands, spreading later to other places
what causes autoimmune diseases
causes are being researched - thought to be both environmental and genetic
outline the blood clotting process
1- endothelium is cut / damaged
2- this activates mast cells, causing the secretion of cytokines and histamines
3- exposed collagen fibres stimulates secretion of serotonin and activates platelets
4- platelets cause the secretion of thromboplastin which causes the release of Ca2+, and with Ca2+ it acts on prothrombin
5- prothrombin is converted to thrombin
6- thrombin acts on fibrinogen, converting it to fibrin
7- fibrin forms a mesh which traps red blood cells, forming the clot
what is the purpose of cytokines in blood clotting
they attract phagocytes
what is the purpose of histamines in blood clotting
causes vasodilation
- this causes blood vessels to be more leaky, pushing out tissue fluid, causing pain + irritation
- also it increases temperature due to increased blood supply which can reduce ability of pathogens to reproduce? and causes irritation
what is the purpose of serotonin in blood clotting
it restricts blood supply + helps platelets cluster together preventing blood loss
platelets definition
short lived cell fragments, no nucleus, formed in bone marrow before being released into blood
what is thromboplastin
this is a clotting factor - it works with Ca2+
what is prothrombin
a blood protein
what is thrombin
an active enzyme, made from prothrombin
what is fibrinogen
a soluble blood protein
what is fibrin
an insoluble blood protein formed from fibrinogen
what type of disease is HIV
viral
what type of cells does HIV affect - and what can be inferred about how + the consequences of the disease
white blood cells
- they may be able to move into the white blood cells through a transport protein that is a similar / complementary shape
- this would impact the immune system, this could link to the cause for AIDS
what is the treatment for HIV
retroviral drugs
how is HIV transmitted
sexually, through exchange of bodily fluids
