Communicable diseases Chapter 12 Flashcards
what are all the types of pathogens
bacteria, viruses, protista and fungi
how do viruses attack and damage the host tissues
viral genetic material is inserted into the host DNA of the host cell, then when the host cell multiplies more viral genetic material is created, which then bursts out the cell
how do some protoctista attack and damage the host tissues
take over cells and break them open by digesting and using the cell contents as they reproduce
how do fungi attack and damage the host tissues
digest living cells and destroy them or produce toxins
how do bacteria damage the host tissues
by producing toxins
what is ring rot
a bacterial disease of potatoes, tomatoes and aubergines, damages leaves, tubers and fruit, once it infects a field, the field cannot be used for two years, NO CURE
what is tobacco mosaic virus
virus that infects tobacco plants, tomatoes, peppers, cucumbers, petunias and delphiniums, damages fruit, flowers and leaves, stunts growth and reduces yield and lead to almost total crop loss, resistant strains have been produced
what is potato blight
protist, the hyphae penetrate host cells, destroying leaves, tubers and fruit, no cure but resistant strains
what is black sigatoka
fungi,banana disease which attacks leaves, hyphae penetrate and digest the cells, can cause a 50% reduction yield, resistant strains produced
what is TB
a bacterial disease that damages and destroys lung tissue and suppresses the immune system
what is bacterial meningitis
a bacterial infection of the meninges of the brain which can spread to the rest of the body and cause septicaemia. 10% of those infected will die, vaccines against certain types have been developed and antibiotics can cure it
what is HIV/AIDS
virus, HIV targets T helper cells in the immune system of the body, gradually destroys someone’s immune system so they are more open to other infections, spreads via bodily fluids, no vaccine or cure but can be treated using anti-retroviral drugs
what is influenza
viral infection of the ciliated epithelial cells in the gas exchange system, kills them leading to easier infection, spread via respiratory droplets in the air, no cure
what is malaria
spread by bite of infected mosquitoes, the protoctista reproduces inside the female mosquito, it invades the red blood cells, liver and brain, the disease recurs making people weak to infection, no vaccine and limited cures
what is ring worm
a fungal disease affecting dogs, cats, cattle and humans, antifungal creams can cure it
what is athlete’s foot
a human fungal disease that digests the warm moist skin in between the toes, creams can cure it
what are examples of direct transmission in animals
direct contact, inoculation (e.g. animal bite), and ingestion
what are examples of indirect transmission in animals
fomites (inanimate objects), droplet infection, vectors, transmission between humans and animals
factors affecting the transmission of communicable diseases between humans
overcrowding, malnutrition, compromised immune system, poor disposal of waste, climate change, culture and infrastructure, socioeconomic factors
what are examples of indirect transmission in plants
soil contamination and vectors
factors affecting the transmission of communicable diseases in plants
planting varieties of crop that are susceptible to disease, overcrowding, malnutrition, damp and warm conditions increases spread of pathogens and spores, climate change
what do plants produce in response to a pathogen
a polysaccharide called callose
what does callose do?
act as a barrier to prevent pathogens entering plant cells around the site of the infection
plant defensive chemicals examples
insect repellents and insecticides, antibacterial compounds including antibiotics, antifungal compounds, anti-oomycetes, general toxins
non-specific defences in humans, first line of defence
skin, mucous membranes, lysozymes and expulsive reflexes
what substances do platelets excrete in response to a damaged blood vessel
thromboplastin which triggers a cascade of reactions resulting in the formation of a blood clot
serotonin which makes the blood vessels contract, reducing the blood supply
in an inflammatory response, what chemicals do mast cells produce
histamines and cytokines
what do histamines do
make the blood vessels dilate causing localised heat and redness which stops the pathogens from reproducing, they also make the blood vessel walls more leaky so that blood plasma is forced out and becomes tissue fluid
what do cytokines do
attract phagocytes to the site of infection
why do fevers help to stop infection from spreading
higher temperatures inhibit pathogen reproduction, and the specific immune system works better at higher temperatures
stages of phagocytosis
pathogens produce chemicals that attract phagocytes, the phagocytes move up a concentration gradient to reach them, they then bind to the antigens using their receptors, then the phagocyte engulfs the pathogen, then it forms a phagosome which then combines with a lysosome to form a phagolysosome which then releases lysozymes that break down the pathogen using hydrolysis reactions
what are opsonins
they bind to pathogens and tag them making it easier for other phagocytes to recognise them
what are antibodies
polypeptides, Y-shaped glycoproteins called immunoglobins
what are antibodies made up of
two identical polypeptide chains called the heavy chains, and two shorter polypeptide chains called light chains, held together by disulfide bridges
what is the variable and constant region on an antibody
the variable is the binding site, the constant is the rest of the body
how do antibodies defend the body
acts as an opsonin so the antigen-antibody complex is easily engulfed and digested by phagocytes, once part of the antigen-antibody complex most pathogens cant infect host cells, agglutinins, anti-toxins
where do b lymphocytes mature
the bone marrow
where do the T lymphocytes mature
the Thymus gland
what do T helper cells
have receptors on their cell surface that can bind to antigen presenting cells, produce interleukins which stimulate the activity of B cells which increases antibody production, stimulates the production of other T cells and stimulates macrophages to ingest pathogens
what do T killer cells do
destroy the pathogen carrying the antigen, produce perforin which creates holes in the cell surface membrane of the pathogen so it is feely permeable
what do T memory cells do
live for a long time and part of the immunological memory, if they meet an antigen a second time, they divide rapidly to forma large number of killer T cells that destroy it
what do T regulator cells do
suppress the immune system, acting to regulate and control it, makes sure there is not an autoimmune response, interleukins important in this role
what do plasma cells do
produce particular antibodies to a particular antigen, only lives for a few days but can produce 2,000 antibodies per second whilst alive
what do B effector cells do
divide to form the plasma cell clones
what do b memory cells do
live for a long time and provide the immunological memory, programmed to remember a specific antigen and enable the body to make a very rapid response when a pathogen carrying that antigen is encountered again
cell mediated immunity
T lymphocytes respond to the cells of an organism that have been changed in some way,
in the non-specific defence system, macrophages engulf and digest pathogens in phagocytosis, they then form APCs
T helper cells become activated and produce interleukins which causes more t cells to clone themselves
The cloned t cells: develop into t memory cells, produce interleukins that stimulate phagocytosis and for b cells to divide, stimulate development of clone t killer cells
Humoral immunity
The body responds to antigens found outside the cells. Produces antibodies
Activated T cells bind to the B cell APC, clonal selection- the B cell with the correct antibody is chosen for cloning.
Interleukins produced by the activated T helper cells activate the B cells, which divide by mitosis to give clones or plasma cells and B memory cells - clonal expansion.
The plasma cells produce antibodies that bind to the antigens and disable them, or act as opsonins or agglutinins.
what is an autoimmune disease
when the immune system stops recognising self cells and starts to attack healthy body tissues
what are used for treatments of autoimmune diseases
immunosuppressant drugs, which prevent the immune system from working, which prevent the body from defending against communicable diseases
what is natural active immunity
when your immune system meets a pathogen for the first time, its activated and antibodies are formed. T and B memory cells are produced so that your immune system recognises the antigens the next time and can destroy it before it causes disease symptoms.
what is natural passive immunity
inheriting antibodies from the mother either through the placenta or breast milk (colostrum), the infant gut allows the glycoproteins to pass through the bloodstream without being digested. Lasts until the baby starts to make its own antibodies.
what is artificial passive immunity
antibodies formed in one body, extracted, then injected into the bloodstream of another individual, doesn’t last long
what is artificial active immunity
vaccine of antigens, can last a long time but sometimes require boosters
what is an epidemic
when a communicable disease spreads rapidly to a lot of people at a local or national level
what is a pandemic
when the same communicable disease that caused an epidemic spreads rapidly across a number of countries and continents
why do vaccines have to be changed regularly to prevent epidemics
so that they remain effective against the constantly changing antigens
what is herd immunity
when a significant number of a population have become vaccinated gives protection to people who haven’t had the vaccine, minimal opportunity for an outbreak to occur
what are some examples of diseases that cant be prevented by vaccine
malaria- plasmodium is very evasive, spends time in RBD so is protected by self antigens from the immune system, within an infected individual its antigens reshuffle
HIV- enters macrophages and T helper cells so disables the immune system itself
how was penicillin first discovered
discovered by Alexander Flemming in 1928, Howard Florey and Ernst chain developed an industrial process for making the new drug
what is the source and action of Penicillin
commercial extraction originally from mould on melons, antibiotic
what is the source and action of Docetaxel
derived originally from yew trees, treatment for breast cancer
what is the source and action for aspirin
based on compounds from willow bark, painkiller, anticoagulant, anti-pyretic (reduces fever) and anti-inflammatory
what is the source and action of prialt
derived from venom of a cone snail found in the oceans around Australia, painkiller 1000 times more effective than morphine
what is the source and action of vancomycin
derived from a soil fungus, powerful antibiotic
what is the source and action of digoxin
based on digitoxin, originally extracted from foxgloves, powerful heart drug used to treat atrial fibrillation and heart failure
what is pharmacogenomics
the science of interweaving knowledge of drug actions with personal genetic material
what is synthetic biology
developing bacteria to produce more drugs than usual, use bacteria as biological factories, mammals also genetically modified to produce much needed proteins in their milk
what is selective toxicity
antibiotics interfere with the metabolism of bacteria without affecting the metabolism of the human cells
how can we reduce the amount of antibiotic resistant infections
minimising the use of antibiotics, ensure that every course of antibiotics is completed, good hygiene
