Biology topic 3 Flashcards
(31 cards)
What is a pathogen?
Microorganism that enters the body and causes disease. They can cause communicable infections, diseases, which easily spread.
Both plants and animals can be affected by pathogens.
List the four main pathogens
Bacteria, viruses, protists, fungi
What are bacteria?
Very small living cells about 1/100th the size of your body cells, can reproduce rapidly inside your body. Make you feel ill by producing toxins that damage your cells and tissues.
What are viruses?
Viruses aren’t cells. They are tiny 1/100th the size of bacterium. They can reproduce rapidly inside your body. They live inside yourself and replicate themselves using the cells machinery to produce many copies of themselves. The cell, usually then Bursts, releasing all of the new viruses. The cell damage is what makes you feel ill.
What are protists?
Single celled eukaryotes. Some protists are parasites. Parasites live on or inside other organisms and can cause them damage. Often transferred to the organism buy a vector which doesn’t get the disease itself (carried by an insect).
What are fungi?
some are single celled, some have a body made up of hyphae (thread like structure). The hyphae grow and penetrate human skin and the surface of plants, causing diseases. They can produce spores which spread to other plants and animals.
What are the three ways pathogens can be spread?
Water - picked up in dirty water from drinking or bathing eg. Cholera is a bacterial infection, spread by drinking
contaminated water.
Air - can be carried in air, then breathed in. Some Airbourne pathogen is a carried in the air in which droplets produced when you cough or sneeze such as influenzer.
Direct contact - some pathogen is a picked up by touching contaminated surfaces including skin. Athletes foot is a fungus which makes skin itching flake off, mostly spread by touching the same things as an infected person such as shower floors.
What are the three viral diseases you need to know?
Measles, HIV, tobacco mosaic virus.
What is measles?
Viral disease spread by droplets from sneezes or coughs. People develop red skin, rash or fever. Can be fatal if there are complications, can lead to pneumonia or brain infection called encephalitis. Most people are vaccinated against measles when they’re young.
What is HIV?
A virus spread by sexual contact, or by exchanging bodily fluids such as blood, can happen when sharing needles. Causes flu like symptoms, can be controlled with antiretroviral drugs which stop the virus replicating.
The virus attacks the immune cells.
It can’t cope with other infections or cancers, at this stage, it’s known as AIDS.
What is tobacco mosaic virus?
Affects many species of plants, such as tomatoes. Causes a mosaic pattern on the leaves of plants, causing them to become discoloured, meaning they can’t carry out photosynthesis of as well so the virus affect growth.
Give an example of a fungal disease
Rose black spot - fungus causing purple or black spots on the leaves of rose plants, they turn yellow and drop off.
This means less photosynthesis happens so the plant doesn’t grow. It spreads through the environment in water or by the wind. it can be treated by fungicides, and stripping the plant if it’s affected Leaves which must be destroyed.
Give an example of a disease caused by protist
Caused by a protist.
Part of a malarial protist’s life-cycle takes place inside the mosquito, which of factors that pick up the mallarial protest when they feed on an infected animal.
Each time the mosquito feeds on another animal, it’s infected by inserting a protist into the animals blood vessels.
Malaria, causes, repeating episodes of fever, and can be fatal.
The spread of this disease can be reduced by stopping the mosquitoes from breeding.
People can be protected from mosquitoes, using insecticides and mosquito nets.
Give an example of two bacterial diseases
Salmonella, gonorrhoea
What is salmonella?
Bacteria, causing food poisoning.
Causes people to suffer from fever, stomach cramps, vomiting and diarrhoea.
Symptoms caused by toxins bacteria produce. Can be Court from eating contaminated food.
In the UK, most poultry is given a vaccination against salmonella to control the spread of the disease.
What is gonorrhoea?
A sexually transmitted disease.
STDs passed on by sexual contact.
Caused by bacteria.
Symptoms of pain when urinating, and thick, yellow or green discharge from the vagina the penis.
Used to be treated with antibiotics and penicillin, but this has become harder because strains of bacteria have become resistant to it.
To prevent the spread of it, people can be treated with antibiotics and should use barrier methods of contraception.
What are the four ways spread of disease can be reduced or prevented?
Being hygienic.
Destroying vectors (use of insecticides)
Isolating infected individuals.
Vaccinating people.
Explain the bodies defence system
The human body has features which stop lots of nasties is getting inside. (e.g. skin acts as a barrier to pathogens, and secretes, antimicrobial substances, which kill pathogens).
Hair and mucus in your nose trap particles which could contain pathogens.
The trachea and bronchi ( breathing pipes) are lined with cilia (hair) which waft mucus up the back of the throat, where it can be swallowed.
The stomach produce is hydrochloric acid, killing pathogens.
How does your immune system attack pathogens?
If they make it into your body, your immune system destroys them. The most important part of the system is white blood cells which travel in your blood and crawl into every part of you constantly patrolling for microbes, they have three lines of attack;
1) Consuming them - white blood cells can engulf foreign selves and digest them (phagocytosis).
2) Producing antibodies - each invading pathogen has an antigen on its surface, when white blood cells come across this, they will produce proteins called antibodies to destroy them. (These are specific to that type of antigen and won’t look onto any others). The antibodies are produced rapidly and carried around the body to find similar bacteria. If the person is infected with the same pathogen again, they will be immune to it as the blood cells know which antibodies to reproduce.
3) Producing antitoxins - these counteract toxin is produced by the invading bacteria.
What is a vaccination?
When infected with a new pathogen white blood cells, take a few days to learn how to deal with it making you ill.
Vaccinations inject small amounts of dead, or in active pathogens, which are harmless, but get the white blood cells to produce the correct antibodies for if you become ill with that in the future
If live pathogens of the same type appear, after that white blood cells can rapidly produce antibodies to kill of the pathogen.
What are the positives of vaccinations?
Help control lots of communicable diseases that were once common in the UK, such a small pots.
Big outbreaks of disease called epidemics, can be prevented if a large people are vaccinated.
What are the negatives of vaccinations?
You may be vaccinated, but if a significant number of people aren’t the disease will spread quickly anyway.
Vaccines don’t always work and sometimes don’t give you immunity.
You can sometimes have bad reactions to them, but they are very rare.
Which drugs relieve symptoms?
Painkillers are drugs which relieve pain, but they don’t tackle the cause of the disease or kill pathogens they just reduce symptoms.
Which drugs cure the problem?
Antibiotics such as penicillin, they kill bacteria, causing the problem without killing your own body cells, different antibiotics, kill different types of bacteria.
They don’t destroy viruses though. Viruses reproduce using your body cells, makes it difficult to develop drugs, which destroyed just a virus. Use of antibiotics has greatly reduced number of deaths from communicable diseases.
