Section 5 - Health, disease and the development of medicine - Fighting disease, lymphocytes, immunisation and medicine

Question 1

3 physical barriers to stop pathogens entering body and how?

Answer 1

• Skin. If damaged, blood clots quickly seal cuts and keep microorganisms out
• Hairs and mucus in nose trap particles that could contain pathogens
• Cells in trachea and bronchi produce mucus to trap pathogens. Other cells here have cilia which are hair-like structures which waft mucus up to back of throat where it can be swallowed

Question 2

2 chemical barriers to stop pathogens entering body and how?

Answer 2

• Stomach produces hydrochloric acid which kills most pathogens swallowed
• Eyes produce chemical called lysozyme which kills bacteria on surface of eye

Question 3

What do B-lymphocytes produce and what do they attack on a pathogen?

Answer 3

Produce proteins called antibodies to bind on to antigens on pathogen so it can be found and destroyed by other WBC. Antibodies specific to that pathogen and wont lock on to different ones

Question 4

What happens when a pathogen enters the body for the first time? How are memory lymphocytes?

Answer 4

Not enough B-lymphocytes so right amount of antibody produced to overcome infection. Memory lymphocytes produced and remain in body for long time and ‘remember’ specific antigen

Question 5

How does immunisation stop you getting infections?

Answer 5

Dead or inactive pathogens injected into body. They are antigenic (carry antigens) so body makes antibodies and memory lymphocytes to be made. If pathogen gets into body again, memory cause fast secondary response

Question 6

How do antibiotics work?

Answer 6

By inhibiting processes in bacterial cells but not in the host organism

Question 7

What happens in preclinical testing of a drug? 2

Answer 7

• Drugs first tested on human cells and tissues in lab

- Test drug on live animal to test that drug works, to find out how toxic it is and to find best dosage

Question 8

What happens in clinical testing of a drug?

Answer 8

• If drug passes animal tests, then tested on human volunteers in clinical trial
• Drug tested on healthy volunteers to make sure no harmful side effects on normal body working
• If results good, drugs tested on people suffering from illness and optimum dose found (most effective and fewest side effects)
• Patients randomly put into 2 groups. One given new drug, other given placebo to allow for placebo effect
• Clinical trials are blind. Sometimes double blind

Question 9

What is a placebo and placebo effect?

Answer 9

Placebo - substance that looks like drug but doesn’t do anything
Placebo effect - when patient expects treatment to work and so feels better even though treatment isn’t doing anything

Question 10

What are blind and double blind trials?

Answer 10

Blind - patient in study doesn’t know if they’re getting drug or placebo
Double blind - neither patient nor doctor knows until all results gathered so doctors monitoring patients and analysing results aren’t subconsciously influenced by their knowledge