Infection and Response Flashcards
What are pathogens?
Pathogens are disease causing micro-organisms
E.g. bacteria, viruses, fungus, protists
What are Bacteria?
Bacteria are single celled organisms, prokaryotes - much smaller than eukaryotes
What are good uses of bacteria?
to make food like cheese and yogurt
to treat sewage
to make medicine
How do bacteria divide?
Binary fission (splitting in 2), reproduce rapidly
How do bacteria induce symptoms?
Bacteria produce toxins which affect the cells and make you feel ill, and sometimes directly damage and destroy cells
How do viruses induce symptoms?
Viruses take over your cells –> they live and reproduce inside your cells, damaging and destroying
What are 3 ways bacteria are spread?
- direct contact - STDs - can also infect person through cuts scratches and needle punctures that give access to blood, infected piece of a plant left in a field can infect new crops
2.air - droplet infection - tiny droplets are expelled when a person sneezes or coughs into the air. People nearby breathe in these droplets that contain pathogens
- Water - fungal spores in contaminated water can spread plant diseases. Humans eating raw uncooked contaminated meat
What is a group of bacteria called?
colony
What is aseptic technique + examples
-sterilise the work bench and all the equipment.
-sterilise hands and wear sterile gloves
-sterilise innoculating loop in blue flame
-open vial containing bacteria at an angle, close to the flame of the bunsen burner to maintain a sterile field
-open petri dish at an angle close to the flame of the bunsen burner
-sterilise innoculating loop before and after each use
What is growth of bacteria affected by?
growth rate of bacteria is affected by temperature, available nutrients, O2, pH
What is a vaccine
a dead or inactive antigen
What are viruses?
Viruses are even smaller than bacteria
Viruses take over your cells –> they live and reproduce inside your cells, damaging and destroying
What are the right conditions to culture bacteria in?
a culture medium ( agar gel), warmth and oxygen
Where can unnecessary contamination come from? (bacteria growth)
skin, the air, soil, water - this must be avoided - harmless bacteria can mutate into harmful bacteria
What aseptic techniques must be used before and whilst growing and preparing to grow bacteria?
-sterilise the work bench and all the equipment.
-sterilise hands and wear sterile gloves
-sterilise innoculating loop in blue flame
-open vial containing bacteria at an angle, close to the flame of the bunsen burner to maintain a sterile field
-open petri dish at an angle close to the flame of the bunsen burner
-sterilise innoculating loop before and after each use
What temperature is bacteria cultured at and why?
cultures are incubated at 25 degrees celsius as if it is closer to human body temp (37) then any mutating bacteria can become very harmful
What is growth of bacteria affected by?
temperature, available nutrients, O2, pH
How do you calculate growth of bacteria?
bacteria at the end of the growth period = bacteria at start of growth period x 2 ^number of divisions
What are ways to prevent the growth of bacteria?
- raise or lower the temperature
- disinfectant - kills bacteria in the ENVIRONMENT
- antiseptic - kills bacteria that is safe to use on the skin
- antibiotics - kills bacteria and is safe to use IN the body
What are examples of viral infections?
- Measles
- HIV (human immunodeficiency virus)
-TMV (tobacco mosaic virus) (plants)
Measles
Main symptoms = fever and red rash
Spread by droplet infection
An infected individual must be isolated to stop the spread
the spread can also be stopped using the vaccine
HIV (human immunodeficiency virus)
- Starts off like a flu-like illness
- Can be hidden for many years
- Eventually the immune system becomes so damaged that it can no longer work properly –>
- This stage is called AIDS (Acquired Immune Deficiency Syndrome)
- HIV is spread through sexual contact, bodily fluids (blood on needles and transfusions) and from mother to baby in breast milk
- No cure
What is the time between HIV and AIDS affected by?
The time between HIV and AIDS is affected by:
1. nutrition
2. overall health of person
3. access to antiretroviral drugs
TMV (Tobacco Mosaic Virus)
- causes a mosaic pattern on leaves due to cells being destroyed
- this affects the growth of the plant
- spread by contact and insects can act as vectors
- No treatment so farmers grow TMV-resistant strains of plants
What are examples of bacterial infections?
- Salmonella
- Gonorrhoea
Salmonella
- Found in raw meat, poultry, egg and egg products like mayonnaise
- In out bodies, they disrupt the balance of natural bacteria and cause salmonella food poisoning
- A common cause is eating uncooked or unhygienically prepared food
- Symptoms develop within 8-72 hours of eating
- Abdo cramps, vomiting, diarrhoea, BUT it can be fatal in VERY young or VERY old people
Gonorrhoea
- STD
- Has symptoms in the early stages and then becomes symptomless
Symptoms: - A thick yellow/green discharge from the genitals and pain on urination
- Untreated, it can cause long term pelvic pain, infertility and ectopic pregnancies (baby is outside the womb)
- Babies born to infected mothers may have severe eye infections or be blind
- Prevented by the use of condoms and reducing the number of sexual partners, abstinence
What are examples of fungal infections?
- Athlete’s foot
-Rose black spot disease
Athlete’s Foot
- Athlete’s foot - skin condition
-Can be treated using antifungal drugs but hard to treat deep tissue infections
-Damaged heart valves can develop serious fungal infections
Rose Black Spot Disease
- Fungal disease of rose plants
- Causes purple or black spots on the leaves and is a nuisance for garden or commercial flowers
- Weakens plants and stunts growth
spread by fungal spores being carried around in wind and water (rain) - Prevent it by removing or burning affected leaves and using chemical fungicides
What is an example of a Protist?
Malaria
Malaria
the protists reproduce sexually in mosquitos and asexually in humans
protists are passed into the bloodstream and affect the liver and red blood cells
causes recurrent episodes to fever and shaking
protists burst out of red blood cells
How can Malaria be prevented/treated?
Treated by:
-Using insecticide impregnated insect nets - to prevent biting
-Prevent the mosquitos to breed by removing standing water and spraying with insecticide to kill larvae
-Travellers can take anti-malarial drugs
How do platelets protect from a wound?
when there is a cut platelets form a scab covering the wound
What do lymphocyte cells do?
produce antibodies and antitoxins
What 2 types of white blood cells are there?
Phagocytes and Lymphocytes
What are examples of plant defences?
-Thorns, poisons, hairy stems or leaves to deter larger herbivores
-Drooping or curling at touch - to drop insects and shock larger herbivores
mimicry
How do vaccines work?
1- Vaccine is injected
2- Body recognises it and treats it as foreign
3- Lymphocytes make antibody for the antigen
the shape of the antibody is stored as a memory cell
4- The next time the body is re-introduced to the antigen, it will make lots of antibodies quicker using the memory cell
5- So it will destroy all of the pathogens before they cause symptoms
What does MMR stand for
Measles, Mumps and Rubella vaccine
What is Herd Immunity?
Large proportion of population is immune to disease (due to vaccine) –> spread of pathogen is decreased and disease may disappear
What must a good drug be?
- Effective - must prevent
- Safe - must not have bad side effects or be too toxic
- Stable.- must be able to store it under normal conditions
- Successfully have entered your body done its work and left
What is the process of preclinical testing?
-Testing on live cells and animals
- Drugs that pass this move on to clinical testing
(this is testing in humans)
- First low doses are given to healthy people to see if it is safe
- If it is safe it is given patients, and if it works it is trialled in larger groups
What are Double-blind trials?
Double-blind trials: group of patients getting the treatment AND the doctors giving the treatment do not know who is getting what - they are both blind
What is HPV?
HPV (Human Pappiloma Virus)
- causes cervical cancer in human
What is a risk factors for cervical and breast cancer?
Genetics
What health effects can alcohol lead to?
- Heavy alcohol usage can lead to cirrhosis in the liver - cirrhosis is when living cells are replaced by scar tissue
- Alcohol is a carcinogen
What is the effect of alcohol on pregnant women?
- Pregnant women drinking can lead to fetal alcohol syndrome
- Pregnant women drinking can lead to miscarriages, stillbirths, premature births and low birthweight
