B3 - Infection and Response Flashcards
Pathogens
Microorganisms that enter the body and cause disease
What do pathogens cause?
Communicable diseases (they can spread around easily)
Can both plants and animals be affected by pathogens?
Yes
Give 4 different types of pathogens
Bacteria, viruses, protists, fungi
Bacteria
Very small cells (1/00th the size of your body cells) which can produce rapidly inside your body
They make you fell ill by producing toxins that damage your cells and tissues
Viruses
Extremely small (1/100th the size of a bacterium)
They can reproduce rapidly inside your body
They have to live inside a living organism to replicate themselves using the cells’ machinery to produce many copies of themselves. Then it bursts and releases new viruses. Cell damage makes you feel ill
Protists
All protists are called eukaryotes and most of them a re single-celled
Some protists are parasites which live on or inside other organisms which can cause them damage
Fungi
Some fungi are single-celled and others have a body which is made up of hyphae. These hyphae can grow and penetrate human skin and the surface of the plant, causing diseases. The hyphae can produce spores which can be spread to other plants and animals
Give some ways pathogens can be spread
Water
Air
Direct Contact
Give the 3 viral diseases
Measles
HIV
Tobacco
How are measles spread?
Droplets from an infected person’s sneeze or cough
Symptoms of measles
Red skin rash and show signs of a fever
Why can measles be very serious
If their are complications e.g. pneumonia and encephalitis
How can measles be prevented?
When most people are young, they are vaccinated against it
How is HIV spread?
Sexual contact or exchanging bodily fluids e.g. share needles
HIV symptoms
HIV initially causes flu-like systems for a week
How can HIV be controlled?
Antiretrovial drugs which can stop the virus replicating in the body
What does the HIV virus do?
It attacks the immune cells
What is late stage HIV infection or AIDS?
When the body’s immune system is badly damaged and it can’t cope with other infections or cancers
TMV symptoms on plants
Causes a mosaic pattern on the leaves of the plants
What does TMV do?
Affects the growth of the plant as they plant cannot carry out photosynthesis
Give an example of a fungal disease
Rose black spot
Rose black spot symptoms on plants
Purple or black spots which can turn yellow and drop off
How is rose black spot spread?
Water or the wind
How can plants be treated from rose black spot?
Fungicides and by stripping the plant of its affected leaves
Give an example of a protists disease
Malaria
How is malaria transported?
Through a mosquito (vector) in which they feed on an infected animal and feeds on an uninfected animal
How does malaria get from the mosquito to the organism?
It infects it by inserting the protists into the animal’s blood vessel
Malaria symptoms
Repeating episodes of fever
How can you stop the spread of malaria?
Stopping mosquitoes from breeding and from using insecticides and mosquito nets
Give 2 examples of bacterial diseases
Salmonella and Gonorrhoea
Salmonella
A type of bacteria that causes food poisoning
Salmonella symptoms
Fever, stomach cramps, vomiting and diarrhoea
What causes salmonella symptoms
Toxins
How is salmonella caught?
From eating food that has been contaminated with Salmonella or unhygienic conditions
How can you prevent salmonella?
Chickens and turkeys are given vaccinations against Salmonella
Gonorrhoea
STD (bacteria)
How are STDs passed on?
Through sexual contact
Gonorrhoea symptoms
Pain when they urinate or yellow/green discharge from the vagina or penis
What was gonorrhoea originally treated with?
An antibiotic called penicillin but this has become trickier now because strains of the bacteria have become resistant to it
How can you prevent the spread of gonorrhea
Antibiotics and barrier methods of contraception such as condoms
Give some general ways that you can prevent the spread of disease
Being hygienic
Destroying vectors
Isolating infected individuals
Vaccination
Give some physical defensive features your body has
- Skin acts as a barrier to pathogens
- Hairs and mucus in your throats to trap particles that could contain pathogens
- trachea and bronchi are lined with cilia which waft the mucus up to the back of the throat where it can be swallowed
- stomach produces hydrochloric acid which kills pathogens that make it that far from the mouth
How does you immune system attack pathogens?
White blood cells patrol for microbes and they have 3 lines for attack
Give the steps white blood cells take to attack pathogens
1) phagocytosis
2) produce antibodies
3) produce antitoxins
Phagocytosis
White blood cells engulf foreign cells and digest them
Producing antibodies
1) Every pathogen has unique molecules called antigens on its surface
2) When some types of white blood cells come across a foreign antigen, they will start to produce antibodies (proteins) to lock onto the invading cells so that they can be found and destroyed by other white cells. The antibodies produced are specific to that antigen and won’t lock onto any others
3) Antibodies are produced rapidly and carried around the body
4) If the person is infected by the same pathogen again. white blood cells will rapidly produce the antibodies to kill it
Producing antitoxins
These counteract toxins produced by invading bacteria
Vaccinations
They work by injecting small amounts of dead or inactive pathogens which carry antigens which causes your body to produce antibodies to attack them even though the pathogen is harmless
Once a person has been vaccinated, how does that prevent the real disease?
White blood cells can rapidly mass-produce antibodies to kill of the pathogen
Pros for vaccination
- Vaccines have helped control lots of communicable diseases
- Big outbreaks of disease if a large percentage of the population is vaccinated (herd immunity
Cons of vaccination
- Vaccines don’t always work/they sometimes don’t give you immunity
- You can sometimes have a bad reaction to a vaccine. But bad reactions are very rare
Painkillers
Drugs that relieve pain. However they don’t actually tackle the cause of the disease or kill pathogens, they just help reduce the symptoms.
Antibiotics
They kill the bacteria causing the problem without killing your own body cells
Give examples of a painkiller
Aspirin
Give an example of an antibiotic
Penicillin
Why can antibiotics sometimes not work?
Because bacteria can mutate causing them to be resistant
What is the process of bacteria becoming anti-biotic resistant
Bacteria that survive the antibiotic will survive and reproduce and the population of the resistant strain will increase (natural selection)
How can you slow down the rate of antibiotic resistance?
Avoid over-prescribing antibiotics and only for something more serious
Why is it important to finish the whole course of antibiotics?
To prevent the rate of antibiotic resistance
Where do many drugs come from?
plants because they produce a variety of chemicals to defend themselves against pests and pathogens
Aspirin
Used as a pain killer to lower fever which was found in willow
Digitalis
Used to treat heat conditions which was found in foxgloves
How did Alexander Fleming discover antibiotics?
He was clearing out some Petri dishes containing bacteria, and noticed that one of the dishes of bacteria also had mould on it and the area around the mould was free of the bacteria
mould - (penicillium notatum)
penicillin - the substance that killed the bacteria
What are the 3 main stages of drug testing?
Preclinical testing (on tissue) Preclinical testing (on live animals) Clinical trials
What happens during the first step of drug testing?
1) Drugs are tested on human cells and tissue
2) You can’t use human cells and tissues to test drugs that affect whole or multiple body systems because of an intact circulatory system
What happens during the second step of drug testing?
1) Test the drugs on live animals, this is used to test efficacy, toxicity and dosage
2) New drugs must be tested on 2 live mammals. Some people it’s cruel to test on animals, but others believe this is the safest way to make sure a drug isn’t dangerous before it’s given to humans
Efficacy
Whether the drugs works and produces the effect you’re looking for
Toxicity
How harmful it is
Dosage
The concentration that should be given, and how often it should be given
What happens during the third step of drug testing?
1) If the drug passes the tests on animals, it’s tested on human volunteers in a clinical trial
2) First it is tested on healthy volunteers to prevent that it doesn’t have any harmful side effects and dosage increases
3) If the tests on healthy people succeeded, drugs can be tested on people suffering from the illness and the optimum dose is found
4) To test how well the drug works, patients are randomly put into 2 groups. One is given the new drug , and the other is given a placebo. This is so the doctor can see the difference the drug makes - it allows the placebo effect
5) Clinical trials are blind and the patient doesn’t know what they are getting. It is double-blind because the doctor doesn’t know until all results are gathered. This prevents the doctors getting influenced by their knowledge
6) Peer reviewed
Placebo
A substance that’s like the drug being used tested but doesn’t do anything
Placebo effect
When the patient expects the treatment to work and so feels better, even though the treatment isn’t doing anything
