B6 Preventing And Treating Diseases Flashcards
What is the human defence system made out of
The general defence system
the specific defence system
Where can pathogens into the body
Eyes, nose, mouth, cuts, ear and the penis or vagina
Is the general defence system
Tries to stop pathogens entering the bloodstream
made up of the bodies natural barriers
they act against pathogens
What are the general defence system barriers
Skin
stomach acid- hydrochloric acid
Mucus
earwax
What is this specific defence system
If the general defence system fails the body relies on the specific defence system
Made up of white blood cells found in the blood
What are the two types of white blood cells
Phagocytes
Lymphocytes:
What does phagocytes do
engulf pathogens and digest them making them harmless
What does Lymphocytes do
produce antibodies in response to ‘foreign’ antigens.
The antibodies attach to the antigens destroy them.
They also can produce antitoxins which cancel out the effect of the pathogen’s toxins.
What are antigens
Every cell in our body has one
They are like ID cards meaning that the body can figure out if it is meant to be in your body or not
What are memory lymphocytes
These are the cloned remains of the original lymphocyte
Which means that if that pathogen attacks again the body can produce antibodies quicker than the original time
How does a vaccination provide immunity?
A dead/weakened/inactive pathogen is injected into the patient’s bloodstream. The pathogen still retains the antigens.
Specific lymphocyte recognises the specific antigens and 1) produces clones of itself and 2) produce large amounts of the correct antibody.
After the lymphocyte has destroyed the pathogen the antibodies are broken down, but the clone of lymphocytes remain in the bloodstream as ‘memory lymphocytes’.
This provides immunity to that specific pathogen.
If the same pathogen re-enters the body the white blood cells respond (more) quickly to produce large amounts of the correct antibodies, preventing infection.
What is herd immunity
Vaccinating a large proportion of the population against a certain pathogen (e.g. flu vaccine).
This is to reduce the number of people getting the disease and avoid an outbreak.
Where did traditional drugs come from
plants
microorganisms
Where dod the heart drug digitalis originate
from foxgloves
Where did the painkiller aspirin originate
from willow
Where did Penicillin originate and who discovered it
from the Penicillium mould
discovered by Alexander Fleming
Why are drugs Rigourously trialled and tested
So they are safe
So do not have any toxic side effects
So the correct dose is given
So they are stable – can be taken under normal conditions and can be stored safely.
What are the different stages of Drug trials
Pre-clinical trials: this is where drugs are tested on cells, tissues and live animals e.g. mice. This is to ensure there are no unwanted side effects.
Clinical trials: this is where the drug is tested on humans. There are 3 stages.
Phase 1: drug is tested on healthy volunteers. Low doses are used.
Phase 2: drug is tested on people who actually have the disease (i.e. the patient).
Double blind trial: Some patients are given the actual drug, some are given a placebo (a ‘fake’ drug without the active ingredient). Neither the patient nor the doctor knows who has been given the drug or placebo. This is to remove bias. At the end of the trial the Scientists from the drug company can compare data.
Phase 3: larger numbers of patients are used. Patients are given the drug or placebo. This is to verify the efficacy/effectiveness of the drug and to determine the correct
dose.
What are antibiotics?
Antibiotics are chemicals that kill (pathogenic) bacteria inside the body. Specific antibiotics kill specific bacteria.
Why do antibiotics not kill viruses?
They do not work against viruses because viruses live and reproduce inside cells.
Why is it difficult for Scientists to develop drugs that kill viruses?
It is difficult to develop drugs that kill viruses as viruses reproduce inside cells.
Therefore it is difficult to just kill the virus and not the body’s tissues too.
How do bacteria become resistant to certain antibiotics?
- Antibiotics kill individual bacterial pathogens of the non-resistant strain.
- Resistant/mutated pathogens survive and reproduce.
- The population of the resistant strain of pathogens increases because they are not
affected/killed by the antibiotic. - The resistant strain will then spread because people are not immune to it and there is
no effective treatment.
How can we reduce the spread of antibiotic resistant bacteria?
Do not prescribe antibiotics for mild infections because they will get better due to the body’s normal immune system
Do not prescribe antibiotics for viral infections / colds / flu because antibiotics do not kill viruses
If you do prescribe antibiotics make sure the patient finishes the full course because
any bacteria left may develop resistance, survive and reproduce rapidly (due to lack
of competition)
