Topic 3: Infection and Response Flashcards
(26 cards)
Pathogens are…?
microorganisms that enter the body and cause disease
Both animals and people can be affected.
Bacteria are…?
very small cells (1/100th the size of your body’s cells) which can reproduce rapidly inside your body. Make you feel ill by producing toxins that damage your cells and tissues.
Viruses are…?
NOT CELLS
Tiny (1/100th a bacterium)
Live inside your cells and replicate themselves rapidly using the cells’ machinery to produce many copies of themselves and burst out, releasing all the new viruses.
This cell damage will make you feel ill
Protists are…?
EUKARYOTES and most are single-celled
Some are parasites - living on or inside other organisms and can cause damage - transferred by a VECTOR
Some Fungi are…?
single-celled. Others have a body made up of hyphae. These hyphae can grow and penetrate human skin and the surfaces of plants, causing disease. They can also produce spores, which can be spread to other plants and animals.
How can pathogens be spread?
Through air touch SHaring of bodily fluids (sex, sharing needles etc) Food Water Animals
Measles
VIRUS
The Measles Virus is spread by droplet infection.
It causes fever and a rash and can be fatal.
There is no cure
Isolation of patients and vaccination prevents the spread of the disease.
HIV?
VIRAL
HIV initially causes a flu-like illness.
Unless it is successfully controlled with antiretroviral drugs the virus attacks the body’s immune cells.
Late-stage HIV infection, or AIDS, occurs when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers.
HIV is spread by sexual contact or by the exchange of bodily fluids, such as blood — occurring when drug users share needles, it can be also be passed from mother to child through breastmilk.
TMV?
VIRUS
The Tobacco Mosaic Virus was the first virus ever to be isolated.
The virus causes a distinctive ‘mosaic’ pattern of discolouration on the leaves at the virus destroys the cells.
It is spread by contact and vectors.
It damages leaves, reduces photosynthesis and can seriously reduce the yield of a crop.
There is no treatment.
Spread is prevented by field hygiene and pest control.
Fungal diseases?
Fungal diseases are caused by fungi and, although there are relatively few that affect people, can be devastating to plants.
Rose Black Spot is a fungal disease spread in the environment by wind and water.
It damages leaves so they drop off, affecting growth as photosynthesis is reduced.
Spread is controlled by removing affected leaves and chemical sprays - but are not very effective.
Diseases by protists?
Protists (a type of single-celled organism) can cause a range of diseases in both animals and plants. They are relatively rare pathogens but the diseases they cause are often very serious and damaging to those infected.
Malaria is caused by parasitic protists and is spread by the bite of female mosquitos.
It damages blood and liver cells causing fevers and shaking.
Malaria can be fatal.
Some drugs are effective if given early, but the protists are becoming more resistant.
Spread is reduced by preventing the vectors from breeding and by using mosquito nets to prevent people from being bitten.
Plant Diseases and symptoms?
Plants can be infected by a range of viral, bacterial and fungal pathogens as well as insect pests.
Plants can be damaged by a range of ion deficiency conditions.
Plant diseases can be detected by a range of symptoms and identified in a number of ways, including gardening manuals involving laboratory tests, some involving monoclonal (forming a clone asexually from a single cell or individual) antibodies.
Some symptoms of a disease in a plant:
Stunted growth (eg nitrate deficiency)
spots on leaves (eg rose black spot0
areas of decay or rotting (eg rose black spot, blights on potatoes)
growths (eg crown galls caused by bacterial infection)
malformed stems and leaves (eg due to aphid/nematode infestation)
discolouration (eg yellowing or chlorosis in magnesium deficiency, mosaic patterns caused by TMV)
presence of visible pests (eg aphids/caterpillars)
Plant defence responses?
Plants have developed many defences against their common pathogens.
Including signalling systems that allow damaged cells to warn other cells within the plant that they are under attack.
Some plants cam even signal to other plants around them, allowing them to get their defences in place.
Physical plant defences against invasion include:
cellulose cell walls
tough waxy cuticles
layers of bark (or dead leaves) which fall off.
Chemical plant defences include antibacterial chemicals and poisons to deter herbivores
Many plants have mechanical adaptations against herbivores such as thorns and hairs, leaves that droop or curl when touched, and mimicry (imitation) to trick animals.
Salmonella?
Salmonella - food poisoning BACTERIAL
fever, stomach cramps, vomiting and diarrhoea
Caused by toxins the bacteria produce
By eating food that’s been contaminated with the bacteria or by being prepared in unhygienic conditions
In the UK, most poultry is given a vaccination against salmonella
Gonorrhoea?
BACTERIAL
An STD - having unprotected sex
pain when urinating
Thick yellowy-green discharge from the vagina or penis
Originally treated with penicillin but is now tricky as strains of the disease have become resistant to it
Treated with antibiotics and should use barrier methods of contraception (condoms)
Reducing the spread of diseases?
Being hygienic
Destroying vectors
Isolating infected individuals
Vaccination
Human defences?
The skin acts as a barrier and it also secretes antimicrobial substances which kill bacteria
Hairs and mucus in your nose trap particles that could contain pathogens
The trachea and bronchi secrete mucus to trap pathogens - are also lined with cilia - hair like structures that waft the mucus up to the back of the throat to be swallowed
The stomach produces hydrochloric acid that kills pathogens that make it that far from the mouth.
The white blood cells and pathogens?
- They consume the pathogens - by engulfing the foreign cells and digesting them - PHAGOCYTOSIS
- Producing antibodies - When WBCs come across foreign antigen (unique molecules on the surface of pathogens) they will start to proteins called antibodies to lock onto invading cells so they can be found and destroyed by other WBCs.
The antibodies produced are unique to that specific antigen.
Antibodies are then produced rapidly and carried around the body to find all similar bacteria or viruses.
If the person is infected with the same pathogen again, the WBCs will rapidly produce the antibodies to kill it - the person is naturally immune to that pathogen and won’t get ill. - Producing antitoxins - To counteract the toxins produced by invading bacteria.
Vaccination?
These involve injecting small amounts of dead or inactive pathogens. These carry antigens, which cause your body to produce antibodies to attack them - even though the pathogen is harmless. Eg = MMR vaccine = Measles, Mumps and Rubella
Pros and cons of vaccination
Herd immunity - If a large proportion of the population is immune to a disease, the spread of the pathogen in the population is very much reduced and the disease may even disappear
They don’t always work
You can have a bad reaction to a vaccine - swelling/fever/seizures.
Drugs to cure/relieve symptoms?
Painkillers- drugs that relieve pain, but don’t actually tackle the cause of the disease or kill pathogens - purely relieving symptoms
Antibiotics - penicillin - actually kill the bacteria causing the problem without killing your cells. Different antibiotics kill different types of bacteria
BUT antibiotics don’t destroy viruses. They reproduce using your body’s cells, making it very hard to develop drugs that do not damage the bodies cells.
Resistant Bacteria?
Bacteria can mutate - sometimes these mutations cause them to be resistant to an antibiotic
If you have an infection, some bacteria might be resistant to antibiotics, so when you treat the infection, only the non-resistant strains will be killed. Meaning that the non-resistant bacteria will survive and reproduce and the resistant strain will increase.
It could cause serious infection that cannot be treated with antibiotics.
eg. MRSA (meticillin-resistant Staphylococcus aureus) causes serious wound infections and cannot be treated by powerful antibiotic meticillin.
To slow down the rate of development of resistant strains, it’s important for doctors to avoid over-prescribing antibiotics and that you finish the whole course when you have to take them.
Drugs that came from plants?
Aspirin = painkiller and to lower fever = From a chemical found in willow Digitalis = heart conditions = From a chemical found in foxglove
Drugs that came from microorganisms?
Alexander Flemming cleared out some Petri dishes containing bacteria. He noticed that one of them containing bacteria had mould on it, and the area around the mould was free of bacteria
He found that the mould (Penicillium notatum) on the Petri-dish was producing a substance that killed the bacteria = penicillin
