communicable disease Flashcards
name for the 4 types of pathogens
bacteria, viruses, fungi and Protoctista
give some information on bacteria
they are classified based on shape and/or cell wall
no membrane bound organelles
prokaryotes
produces toxins that poison/damage host cells. can break down the cell membrane, inactivate enzymes or interact with genetic information and prevent cell division.
give some information on viruses
0.02-0.3um
non living agent
DNA or RNA surrounded by a protein.
reproduce rapidly and take of the biochemistry of the host cell.
good at developing adaptations to treatments
can attack bacteria forming bacteriophages
ULTIMATE PARASITE
take over the cell metabolism and genetic information. then reproduces rapidly. cell bursts open and spread to other cells to cause infection.
give some information on Protoctista
eukaryotes
single or multi cellular
disease causing Protoctista use animals as a host and require a vector to transfer them
digest and use cell component to reproduce.
give some information on
eukaryotes
multicellular
can PHS and digest food extracellularly
saprophytes - feed on dead matter
when they reproduce the make millions of spores which can spread far and rapidly.
digest living cells, destroying them. can also release toxins.
explain a type of staining that enable you to identify the type of cell wall in a prokaryote
Gram staining
gram positive - purple/blue under the microscope. ie MRSA
gram negative - red under the microscope ie e.coli
this is useful because it indicates which antibiotics will be most effective when reacting with the pathogen based on the cell wall.
what is a communicable disease
caused by pathogens and can be passed on from one organism to another causing disease.
give an example of a bacteria disease in plants
ring rot
gram positive bacteria
affects potatoes and tomato’s
effects the entire field so it cannot be used to grow crops for at least 2 years after the infection.
give an example of a viral disease in plants
TMV (Tobacco mosaic virus)
affects tomatoes and peppers
stunts growth and reduces yield
no cure but resistant crop stains are available
give an example of a Protoctista disease in plants
potato blight
cell body penetrates the host cell, destroying leaves.
no cure but resistant strains and careful management of chemical treatments can reduce infection
give an example of a fungal disease in plants
black sigatoka
bananas
cell body penetrates and digests leaves and cells causing them to turn black.
resistant strains are being developed.
no cure but fungicide treatment can reduce the spread.
give an example of a bacteria disease in animals (2)
tuberculosis TB
humans, cows, badgers and pigs
damages and destroys lung tissue supressing the immune system so less able to fight off infection.
curable by antibiotics and preventable by improved living conditions
meningitis
attacks the protective membranes in the brain
can spread to other parts of the body causing blood poisoning
effects mostly young children and teenagers
glass test - red, purple rash that will not disappear when pressure is applied.
vaccines and antibiotics if caught early enough are used as treatments
give two examples of viral diseases
HIV AIDS targets T helper cells in the immune system so people are open to other infections
it is a retrovirus with RNA which transcribes into a single strand of DNA invading the host cell genetic material.
passed from person to person through bodily fluids ie sex, exchange of needles, some unsterile medical practices, mother to baby during breast feeding.
no vaccine and no cure but anti retroviral drugs can slow down the progress of the disease.
influenza effects the ciliated epithelial cells in gas exchange system. it kills them leaving the airways open to secondary infection. can be fatal in young, old and vulnerable people. having the flu one year will leave you with immunity for the next due to the small changes of the antigens on the plasma membrane. occasionally there will be big changes on the surface of the virus which will lead to an epidemic/pandemic as there are no antibodies available.
Zootonic influenza is caught from animals.
give one protocitista disease
malaria - spreads through the bite of a female mosquito (Anopheles) when feeding on humans for blood caused by the pathogen Plasmodium it can invade RBC, liver and the brain. the disease makes people weak and vulnerable to other infections
no vaccine and limited cures but preventative measures can be effective.
using mosquito nets, insecticides, removing standing water, long sleeve clothes and keeping doors and windows shut.
how do you identify pathogens
- pathogens are cultured in the lab and identified with a microscope
-monoclonal antibodies can be used to identity - DNA sequencing technology means pathogens can be identified down to a single mutation.
how do you identify pathogens
- pathogens are cultured in the lab and identified with a microscope
-monoclonal antibodies can be used to identity - DNA sequencing technology means pathogens can be identified down to a single mutation.
give three direct ways that pathogens can be spread in animals
direct contant ie kissing, touching, transmitting faeces on hands
inoculation (break of the skin) ie sex, animal bite or puncture wounds (through sharing needles)
ingestions ie contaminated food or drink
give 3 examples of how pathogens can be indirectly transmitted
fomites inanimate objects sich as bedding and socks ie athletes foot
give 3 examples of how pathogens can be indirectly transmitted
fomites inanimate objects sich as bedding and socks ie athletes foot
droplet saliva and droplets are expelled from your mouth as you talk.
vectors transferred pathogen to a host
water can also be a vector
give 2 fungal diseases
ring worm and athletes foot
how are pathogens transmitted between plants
direct contact with unhealthy plant
soil contamination left behind by infected crops can often effect the next crop.
vectors ie the wind, water splashes, animals and humans
what factors affect the spread of disease in plants
planting varieties of crops that are susceptible to disease, overcrowding, poor mineral nutrition, damp and warm conditions and climate change (increase rain fall and wind which promotes the spread to new areas).
how do plants defend themselves against an attack
receptors in the cell wall respond to molecules that are from the pathogen or chemicals produced during the attack. genes in the nucleus are switched on and defence is initiated.
- callose (1-3 and 1-6 beta linkage) is synthesised and deposited between cell walls in the cell next to be infected, the plasmadesmarta and seive plates. this acts as a barrier preventing the infection from spreading
-lignin is also added to strengthen the cell wall
there is also a range of chemical defences
name the chemical that has a bitter rase, noxious smell and poisonous characteristics. and give an example of a plant that uses this
alkaloids - it can deter/kill herbivores ie tobacco -> nicotine as a response to tissue damage which is poisonous to many insects
what does the chemical tannins do in plants
tastes bitter, can bind to proteins in the gut of herbivores such as cattle and make it hard for them to digest so they are less likely to eat it
what do pheromones do it corn plants
attracts parasitic wasps which kills caterpillar eating the plant by laying eggs on it.
outline the components of the non specific immune system
blood clotting
inflammatory response
fever
phagocytosis
how does the body keep pathogens out
skin contains sebum which prevents them from growing and lots of healthy microorganisms which outcompetes them for space.
mucous membranes in air ways and nose to prevent pathogens entering
lysozymes in tears and urine as well as acid in the stomach
expulsion reflexes ie coughing and sneezing and diahorria and vomitting
describe blooding clotting process
thromboplastin - triggers a cascade of reactions when platelets come in contact with collagen in the skin.
thromboplastin and Ca2+ catalyses the react of prothrombin to thrombin.
thrombin catalyses the reaction of fibrinogen to fibrin which forms a clot.
a scab forms to keep pathogens out, epidermal cells below the scab grow sealing the wound permanently.
describe blooding clotting process
thromboplastin - triggers a cascade of reactions when platelets come in contact with collagen in the skin.
thromboplastin and Ca2+ catalyses the react of prothrombin to thrombin.
thrombin catalyses the reaction of fibrinogen to fibrin which forms a clot.
what role does serotonin play in blood clotting
makes smooth muscle contract so they are narrow and reduce the supply of blood to the area
describe the inflammatory response
associated with heat (prevents the pathogen from reproducing), swelling, redness and pain.
mast cells are activated in damaged tissue which release
-histamines which cause the vessels to dilate (causing swelling) and walls become more leaky so blood plasma is forced out and as a result tissue fluid is left behind.
- cytokines attract WBC to the site
describe the inflammatory response
associated with heat (prevents the pathogen from reproducing), swelling, redness and pain.
mast cells are activated in damaged tissue which release
-histamines which cause the vessels to dilate (causing swelling) and walls become more leaky so blood plasma is forced out and as a result tissue fluid is left behind.
- cytokines attract WBC to the site
how do fevers get rid of pathogens
cytokines stimulate the hypothalamus to rest its thermostat to above 37 degrees to inhibit pathogen reproduction and increase the rate of the specific immune system works.
describe phagocytosis
WBC that engulf and destroy pathogens. neutrophils and macrophages. (pus contains dead WBC)
they recognise the pathogen as non self and attack the pathogen. they engulf forming a PHAGOSOME. which combines with a lysosome to form PHAGOLYSOSOME. the LYSOSOME digest and destroy pathogens
How do APC form
only macrophages
once it has digested a pathogen it combines with antigens from the pathogens membrane. it requires special glycoproteins in the cytoplasm to form hristocompatabile complexes which one to the macrophages cell surface membrane becoming an APC.
what do opsonins do
they bind to pathogen and tag them they are more easily recognised. means phagocytes can bind with more then one pathogen at once.
what do opsonins do
they bind to pathogen and tag them they are more easily recognised. means phagocytes can bind with more then one pathogen at once.
outline the components of the specific immune system
antibodies
lymphocytes
cell mediated immunity
humeral immunity
what is an example of when the specific immune system goes wrong
an autoimmune disease. when the self cells start to attack the healthy body tissue. (sometimes because the T regulatory cells do not work effectively)
treatment can be immunosuppressant drugs which prevent the immune system working but then increase the susceptibility to other infections
examples are type 1 diabetes, arthritis and lupus (skin and joints and causes fatigue)
how do antibodies defend the body against pathogens
tag pathogens so that they are more easily identified by WBC.
once they bind with pathogens they can no longer invade other cells
agglutinins causing the pathogen and antigen complex to clump together so more than one can be engulfed at the same time.
where are T lymphocytes made
thymus gland
where are B lymphocytes made
bone marrow
what do Thelper cells do
bind to APC
produce interleukins (which stimulates B cells and other types of t cells)
what do t killer cells do
they produce a chemical called perforin which kills the pathogen by making holes in its cell surface membrane.
what do t memory cells do
live for a long time. if they meet the same antigen, they divide rapidly into t killer cells destroying the pathogen.
what do t regulatory cells do
suppress the immune system once the pathogen has been eliminated.
there are three types of B cells name them and their role
plasma cells - produce antibodies and release into the blood to increase phagocytosis
B effector - divide into plasma cells
b memory - remember an antigen if it returns, rapid cloning to eliminate it. providing immunological memory
outline the cell mediated immunity response
APC collide with T helper cells with the same receptors. this activates the t helper cells and causes interleukins to be produced - stimulating more T helper cells to divide rapidly by mitosis. the t helper cell clones can develop into
T memory cells
interleukins - phagocytosis
interleukins - b cells divide
t killer cells
what is humoral immunity
response to antigens found outside cells. produces antibodies that are soluble in the blood. not attached to cells
describe the humoral immune response
b cells contain receptors that ate complimentary to only one type of antigen, when the antigen is present it will bind and activate clonal expansion.
what is clonal selection
this is the process in which the complimentary B cells are activated. it begins with a macrophage which undergoes histocompatibility to become and antigen presenting cell. the APC binds with the complimentary T helper cell which divides by mitosis into more T cells and cytokines (to increase phagocytosis) or releases interleukins which cause B cells to be secreted.
why may someone who has had a disease lose immunity after a period of time has passed.
B memory cells may die
no secondary response
no repeated infections
What feature of a pathogen such as Mycobacterium tuberculosis could be altered by a mutation, making a vaccine ineffective?
antigens on the plasma membrane
