B1 - Diseases and Immunity Flashcards
Infectious diseases are caused by microorganisms which are parasites called pathogens. But what can cause non infectious diseases like scurvy, anaemia, diabetes/cancer and red-green colour blindness?
Scurvy - lack of vitamin (c) / vitamin deficiency
Anaemia - lack of iron / mineral deficiency
Diabetes/cancer - body disorder
Red-green colour blindness - genetic inheritance
How can you reduce the risk of cancer?
- sunbathe a little but don’t burn
- don’t eat too much fat and don’t be overweight
- don’t eat too much red meat and processed food
- eat lots of fresh fruit and vegetables
- take regular exercise
- avoid drinking too much alcohol
What causes diseases and what might they do?
Disease causing microorganisms are called pathogens which may damage cells and release chemicals called toxins.
What type of pathogen causes athletes foot, cholera, flu and malaria?
Athletes foot - fungi
Cholera - bacteria
Flu - viruses
Malaria - Protozoa
How does malaria spread?
Malaria is caused by a parasite which is spread by female mosquitoes. When it bites people, they can spread disease. Human and vectors are both hosts for the malaria parasite. It is spread from person to person by vectors.
How do you control malaria?
- sleeping under a net and using insect repellent
- draining areas of stagnant water
- using insecticides to kill them
What are antibiotics? What do they do?
They are chemicals produced by some fungi and bacteria, to kill or prevent the growth of other bacteria or fungi. We use them to kill pathogens when we have a infectious disease.
Why do antibiotics not work on viruses? What is their replacement?
Because viruses do not grow and have no metabolic reactions to be prevented. Antivirals inhibit the replication of viruses inside the host.
Why must we be careful with antibiotics? Give an example?
If antibiotics are not used carefully, then resistant strains of bacteria develop. MRSA is an example, it is resistant to a lot and can cause infections if they get into a wound after surgery.
What barriers does the body have to pathogens?
- skin
- stomach acid
- tears
- mucus in airways
- blood clotting when you cut yourself
What are the two types of white blood cells?
- phagocytes engulf ( ingest) the pathogens
- lymphocytes produce antibodies or antitoxins
What are antibodies? How do they work?
They are proteins.
- Each pathogen has particular antigens which a specific shape on its surface
- each type of antibody has a particular shape and can lock onto a particular antigen
- immune system makes the right sort of antibodies to lock onto the antigens of the particular pathogen that is in your body
- once coated with antibodies, white blood cells can ingest and kill the pathogens
What is immunity?
Once you have recovered from an infection, if the same pathogen enters your body again, your body makes antibodies so quickly that the pathogen is destroyed before it makes you feel ill.
How does immunisation work?
- a small amount of dead or inactivated pathogen is introduced into your body - usually by injection. The dead or inactivated pathogen still have the antigens on their surface.
- some of your white blood cells recognise these antigens on the pathogens and make antibodies
- if later on, the live pathogen gets into your body, you white cells quickly make the right sort of antibodies
- these antibodies destroy the pathogens before they make you ill
What is active and passive immunity? Pros and cons?
Passive - injected with antibodies made in a lab -> you don’t make your own
Active - injected with dead or inactive pathogen -> make your own
Passive is useful if you have been infected by a pathogen that can quickly kill you, but it does not last as long as active immunity.
