infection and response Flashcards
what is the definition of health?
the state of physical and mental well-being.
what are pathogens?
microorganisms that cause infectious disease. these may be viruses, bacteria, protists, or fungi. they may infect plants or animals, and can be spread by direct contact, by water, or by air.
- bacteria and viruses may reproduce rapidly inside the body.
- bacteria may produce toxins that damage tissues and make us feel ill.
- viruses live and reproduce inside cells, causing cell damage.
describe Tobacco Mosaic VIRUS (TMV):
- widespread communicable plant infection; infects many species, e.g. tomatoes, tobacco.
- causes the leaves to discolour in a mosaic pattern; because of this, the rate of photosynthesis is reduced, and the growth of the plant is also reduced.
describe Rose Black Spot: FUNGUS
- caused by a fungus, which can be spread by water or wind (the fungus reproduces sexually to create spores, which can be carried in the wind).
- causes the leaves to develop purple or black spots. the leaves often then turn yellow and fall off.
- this causes the rate of photosynthesis to fall, reducing the rate of growth.
how can Rose Black Spot be treated? FUNGUS
- spray the plants with chemicals which kills fungi (fungicides).
- we can remove the infected leaves and destroy them.
what is a virus?
- not cells and not living.
- 10,000 times smaller than animal cells.
- can’t reproduce by themselves.
- once inside another cell, they can use the cell’s organelles to clone themselves, and can eventually burst the cell.
- this means the new virus cells can find other cells to take over, and destroy them, too.
- this damages our bodies, and makes us feel ill.
describe the measles VIRUS:
- spread by droplets, when an infected person coughs or sneezes.
- results in a red rash across the body and a high fever, and general illness.
- can be serious (and even fatal), but is rare in the UK as nearly everyone is vaccinated against it as a child.
describe the HIV VIRUS:
- stands for ‘Human Immunodeficiency Virus’.
- spread by sexual contact, or by exchanging bodily fluids (e.g. blood, when people share needles).
- causes an inadequate immune system, leaving the person more susceptible to catching other communicable diseases.
what happens when an individual ‘catches’ HIV? VIRUS
- at first, they might get flu-like symptoms for a few weeks (e.g. fever, aches, tiredness)
- at this point, can be cured using antiretroviral drugs.
- they’ll then start to feel better, but if no drugs are used, inside their body, the viruses are doing even more damage to their immune system.
- at one point, their immune system will become so weak that they’ll start to catch unusual infections (and even cancers)
- at this point, the person has developed AIDS, which is classed as a disease altogether, in which the immune system can’t cope anymore.
how can AIDS be treated?
- the individual can take ‘antiretroviral drugs’, preventing the virus from replicating within our bodies.
what is a bacteria?
- single celled organism.
- roughly 100x smaller than our own cells.
- causes disease.
- can reproduce by themselves, but often replicate rapidly inside our bodies due to the good food supply.
- produce toxins, which make us feel ill by damaging our cells and tissues.
what is the salmonella bacteria? BACTERIAL
- causes food poisoning.
- can catch from any food that’s been contaminated with the bacteria, from food prepared in unhygienic conditions, but is most often from chicken that caught the disease while it was alive.
- salmonella is relatively rare in the UK, as most chickens are vaccinated against it.
what are the symptoms and cures of salmonella? BACTERIAL
- symptoms include: a fever, stomach cramps, vomiting and diarrhoea.
- usually passes by itself within a week, and just ensure you stay well hydrated.
describe the bacterial disease gonorrhoea: BACTERIAL
- an example of a sexually transmitted disease (STD).
- passed on through sexual contact.
- symptoms include: pain while urinating, thick yellow/green discharge.
how can you prevent and treat gonorrhea? BACTERIAL
prevention:
- avoid unsafe sex.
- use barrier methods of contraception (e.g. condoms)
treatment:
- we used to use the common antibiotic ‘penicillin’, which would kill it.
- however now, lots of gonorrhoea strains have become resistant to penicillin.
- this means we have to use rarer and more expensive antibiotics.
describe the fungal disease Chalara Ash Dieback: FUNGAL
- fungal disease that affects ash trees.
- causes leaf loss, marks on the bark and dead shoots and branches.
- once a tree is infected, the disease usually kills it, either directly or indirectly (by weakening the tree so that its more susceptible to other diseases).
- spread by fungal spores travelling in the wind.
- infected trees are usually cut down and burnt.
describe the fungal disease Athlete’s foot: FUNGAL
- relatively common infection of the feet.
- itchy rash caused by a fungus growing and multiplying on the skin.
- usually appears between the toes, where it’s warm and dark and moist.
- not usually serious, but should be treated to stop it spreading to other parts of the body or to other people.
- usually treated with creams or sprays, containing fungicides which kills the fungi.
describe the protist disease Malaria: PROTIST
- communicable disease, spread by a pathogen (an example of a protist).
- infected individuals experience repeated bouts of fever, and it can be fatal.
