Fighting disease Flashcards
(23 cards)
What are bacteria and why do they make you feel ill?
Tiny cells (1/100tj size of body cells) They reproduce rapidly inside your body and make you feel ill by damaging your cells and producing toxins
What are viruses and why do they make you feel ill?
They are not cells (1/100th size of bacterium)
They replicate themselves by invading your cell and the cell bursts releasing new viruses and making you feel ill
What is the first part of your bodies defence system?
Skin, hairs, mucus,
How does your body prevent microorganisms getting in through cuts?
Small fragments of cells called platelets allow your blood to clot quickly
How do white blood cells help fight pathogens?
They can engulf foreign cells and digest them
They can produce antitoxins
They can produce antibodies
How do antibodies work?
Every invading cell has antigens on its surface
When your white blood cells find an antigen they begin to produce antibodies to lock on to and kill the invading cells
They are specific and will then produce rapidly to kills similar pathogens
If infected again your body will remember it and you shouldn’t get ill
How do vaccinations work?
Vaccinations involve injecting small amounts of dead or inactive pathogen into your body so that your body will produce antibodies in response so if the real pathogen came you wouldn’t get ill so your body would rapidly mass produce the correct antibody
How do antibiotics work?
They kill the bacteria without killing your body cells
How do bacteria become resistant to antibiotics?
Bacteria can mutate which causes them to become resistant
If you have an infection the resistant bacteria will survive the antibiotics and reproduce and the population will increase.
The resistant strain could cause a serious infection untreatable by antibiotics
How can you test antibiotics in the lab?
Agar jelly (a culture medium)
is poured into a petri dish
Inoculated loops (once flamed) are then used to transfer microbes where they then multiply
Paper disks are soaked in different antibiotics and placed on jelly,
Antibiotic resistant bacteria will grow but non resistant will die
What are the pros of vaccination?
They have helped control lots of infectious diseases which were common in the U.K. (Eg. Polio, measles, tetanus)
Epidemics can be prevented if a large number of the population are vaccinated
What are the cons of vaccination?
They don’t always give you immunity
You can sometimes have a bad reaction to a vaccine e.g. Swelling or fever
How can antibiotic resistant bacteria be avoided?
Avoid over prescribing drugs
What two types of drugs are there?
Ones that relieve the pain and reduce the symptoms but don’t cure it e.g. Paracetamol
Antibiotics that actually kill or prevent growth of bacteria e.g. Penicillin
What can’t antibiotics destroy?
Viruses
What did Semmelweis notice in the 1840’s?
That a huge number of women were dying after childbirth from a disease called puerperal fever
What did he believe spread the disease and what did he do?
Doctors spreading the disease on their unwashed hands
By telling doctors to wash their hands in antiseptic solution he cut the death rate from 12% to 2%
What did the antiseptic solution do?
Kill the bacteria (this wasn’t known at the time so why his method worked couldn’t be proved so it was dropped when he left the hospital)
What dangers do we face with bacteria?
Bacteria can mutate to produce new strains
A new strain could be antibiotic resistant so current treatments would no longer clear infection
Or a new strain that hasn’t been encountered before meaning no one is immune to it this could rapidly spread and cause an epidemic
What dangers do we face with viruses?
They may also mutate making it difficult to develop vaccines against them as when the DNA changes they have different antigens
Viruses could evolve to be deadly and infectious which could cause a pandemic before antiviral drugs were developed
What does a phagocyte do?
ingest and absorb the pathogens or toxins
release an enzyme to destroy them
the phagocytes may also send out chemical messages that help nearby lymphocytes to identify the type of antibody needed to neutralise them
What are the main two types of white blood cell?
Phagocyte
Lymphocyte
What does a lymphocyte do?
Carries antibodies that neutralise pathogens by
they bind to pathogens and damage or destroy them
they coat pathogens, clumping them together so that they are easily ingested by phagocytes
they bind to the pathogens and release chemical signals to attract more phagocytes
Lymphocytes may also release antitoxins that stick to the appropriate toxin and stop it damaging the body.
