Health and disease (Drugs, vaccination and CHD)

Question 1

What are the principles behind vaccination?

Answer 1

• When a person is artificially exposed to antigenic material, the immune system will respond as if it were a real infection and attempt to combat it with an immune response.
• This results in the production of T and B memory cells which will offer the person artificial immunity against the disease.

Question 2

What types of antigenic materials are used in vaccination?

Answer 2

1. Living microorganisms that have very similar antigens as the pathogens you’re vaccinating against. An example is cowpox for smallpox.
2. A modified harmless (attenuated) version of the same pathogen you’re vaccinating against.
3. Dead pathogens that still have their antigens present, usually ground up.
4. Just the antigens from the pathogens you’re vaccinating against.
5. A harmless toxin which would be produced by the pathogen you’re vaccinating against.

Question 3

What vaccination techniques are there?

Answer 3

1. Herd vaccination: Involves vaccinating almost the whole population that may be at risk from the disease (around 80-95%). This prevents people in the population from catching and spreading the disease, which will eventually lead to the extinction of the pathogen. Current programmes include MMR (measles, mumps & rubella) as well as others like pertussus and meningitis.
2. Ring vaccination: Involves only vaccinating people in the immediate vicinity of a known outbreak (street, town…). The idea is to prevent the disease from spreading further and to eradicate the pathogens before they become epidemic.

Question 4

What are the problems faced by vaccinations?

Answer 4

• Pathogens, especially viruses, mutate very quickly and are able to change their antigens. This renders their current vaccinations useless.
• An example is flu, which has killed millions of people over the last century.
• The strain of flu which is dominant changes almost every year, so research needs to be done to ensure new vaccines are available for the different flus each year and in-risk groups can be vaccinated.

Question 5

What is passive immunity?

Answer 5

Passive immunity is the process of injecting the person with ready made antibodies that protect against the disease without stimulating the person’s own immune system. This usually only offers short term immunity.

Question 6

What is active immunity?

Answer 6

Exposing the person to antigenic materials to trigger his/her own immune system to react and produce antibodies (as well as memory cells) against the antigen. This usually offers long term immunity

Question 7

What is natural immunity?

Answer 7

Immunity gained through natural phenomena including natural infections which results in immunity.

Question 8

What is artificial immunity?

Answer 8

Immunity gained by artificially exposure to antibodies or antigens/

Question 9

What is an example of natural passive immunity?

Answer 9

A mother can provide a baby with ready made antibodies through the placenta or breast milk which will protect the baby against infections the mother is immune against, at least until the baby develops a fully functional immune system.

Question 10

What is an example of natural active immunity?

Answer 10

When a person naturally suffers an infection from a disease which causes the production of antibodies and memory cells which offers the person immunity against the disease.

Question 11

What is an example of artificial passive immunity?

Answer 11

Injecting ready-made antibodies directly into a person’s bloodstream to provide the person with some protection against the disease.

Question 12

What is an example of artificial active immunity?

Answer 12

Injecting the person with an antigenic material which triggers an immune response which causes the body to produce antibodies and memory cells, immunising the person from the pathogen with the antigen.

Question 13

Why is there a need for new drugs?

Answer 13

• New diseases are being discovered.
• There are still many untreatable diseases in the world.
• Due to natural selection, many bacteria are becoming resistant to some antibiotics. It may not be long before all bacteria are resistant to present antibiotics, so new ones need to be found before that happens.

Question 14

What are some sources of new drugs?

Answer 14

• Chance: Like penicillin, a new drug may be discovered purely by luck without actually trying to find it.
• Tradition: Many ancient cultures rely on traditional herbal medicine for treating some illnesses. Observing the effects of these traditional medicine may help develop new modern drugs.
• Observation of wildlife:
  1. Monkeys and bears use citrus oil as an insecticide and antiseptic against insect bites.
  2. Chimpanzees swallow leaves to clean their digestive tracts.
  3. Birds line their nests with special leaves to protect their young from infections.

Question 15

How can new drugs be developed through research?

Answer 15

• Research into current drugs and how they work may help us develop them to become more effective or even used to treat new diseases.
• Research into the structure of pathogens may help us tailor drugs to fight certain infections.
• Research into why bacteria are resistant to some antibiotics may help us modify existing antibiotics to bypass resistance.
• Research into the genetics of pathogens may tell us information about how we can combat them or how we can vaccinate against then.

Question 16

What harmful substances does cigarette smoke contain?

Answer 16

• Tar.
• Carbon monoxide.
• Nicotine.
• Mixture of other chemicals in small quantities; some carcinogens.

Question 17

What are the short-term effects of tar?

Answer 17

• Covers alveoli walls and increases diffusion distance for oxygen and carbon dioxide, reducing efficiency of gas exchange.
• May cause constriction of the airways by smooth muscles due to allergic reaction.
• Destroys cilia and stimulates secretion of more mucus.
• Mucus accumulates and may block bronchioles, which may lead to suffocation.
• Pathogens trapped in mucus are not removed as cilia have been destroyed, increasing risks of lung infections like pneumonia.

Question 18

What are the long-term effects of tar?

Answer 18

• Smoker’s cough is an attempt to remove mucus from the airway.
• Smokers cough may damage alveoli and the lining of the airways which are replaced by less flexible scar tissue.
• Smooth muscle lining bronchioles may thicken and restrict airflow into and out of the lungs.
• Infection and inflammation may damage lining of bronchioles and alveoli.
• Phagocytes accumulate and release enzymes to reach airways by breaking down inner walls (mainly elastase).
• Elasticity of alveoli and bronchioles walls lost, so no recoil action is present to push air out of alveoli during expiration, leading to alveoli bursting.

Question 19

How can smoking lead to lung cancer?

Answer 19

• Cigarette smoke contains many carcinogenic chemicals (mainly benzopyrene) that get deposited along the airway in tar.
• These chemicals may enter lung tissue cells and reach the nucleus, where they disrupt the genetic material and may cause mutations.
• Most of these mutations have minor/no effect. However, if a mutation occurs in genes controlling cell division, the cell may become cancerous and may grow into a tumour, causing lung cancer.
• Cancer usually starts in the bronchi and spreads from there.

Question 20

What other diseases can smoking cause?

Answer 20

Chronic bronchitis: Inflammation of the airway lining due to build-up of bacteria-filled mucus. Symptoms include lung irritation, chronic cough and coughing up large amount of mucus.
Emphysema: Due to the loss of elastic fibres in the alveoli, it becomes more difficult for them to expire air which may lead to bursting during expiration. Alveoli also lose their ‘raspberry’ shape and become more rounded, reducing gaseous exchange surface area and making the lungs less efficient. This leads to shortness of breath and fatigue due to poorly oxygenated blood.
Chronic obstruction pulmonary disease: Combination of chronic bronchitis and emphysema which leads to generally unhealthy lungs.

Question 21

What effects does nicotine have on the body?

Answer 21

• Mimics neurotransmitters and increases rate of nervous impulses, making smoker more alert.
• Stimulates release of adrenaline which increases heart rate, blood pressure and breathing rate, leading increased risk of CHD.
• Constricts arterioles to extremities (arms, legs…) and decreases blood flow. This may potentially lead to the need for amputations.
• Makes platelets more ‘sticky’ and increases blood clotting rate and risk of thrombosis.

Question 22

What effects does carbon monoxide have on the body?

Answer 22

• Carbon monoxide binds onto haemoglobin to form carboxyhaemoglobin and prevent them from carrying oxygen. This reduces oxygen carrying capacity of blood and may lead to oxygen starvation of muscles and tissues, especially during exercise.
• Damages artery linings.

Question 23

What causes atherosclerosis?

Answer 23

1. Carbon monoxide and hypertension damages the endothelium of arteries.
2. Damage is repaired by growth of smooth muscles which encourage the deposition of low density lipoproteins if levels are high, platelets and dead blood cells under endothelium, causing buildup of atheromas.
3. Atheromas eventually breaks through endothelium and forms plaque which makes arteries rougher and less flexible. This increases resistance to blood flow. Lumen is also narrowed which restricts blood flow and increases blood pressure.

Question 24

What causes thrombosis?

Answer 24

1. Plaque and nicotine increases the chances of blood clots occurring.
2. Blood clots restrict or even completely stops blood flow in the artery it occurs in.
3. Small part of a blood clot may break away and is carried around body in blood until it blocks a narrow artery it can’t fit through.

Question 25

What causes coronary heart disease?

Answer 25

1. Arteries delivering oxygen and nutrients to cardiac muscles are called coronary arteries.
2. Atherosclerosis and thrombosis restricts or blocks blood flow completely to some cardiac muscles.
3. Cardiac muscle suffers from oxygen starvation and has less oxygen available for aerobic respiration.

Question 26

What effects does CHD have?

Answer 26

• Angina: Severe chest pain that extends up left arm and neck due to damaged cardiac muscles.
• Myocardial infarction (heart attack): Death of a region of cardiac muscle as a result of atherosclerosis and thrombosis which completely block a coronary artery.
• Heart failure: When the heart sustains too much damage and can no longer function properly, due to multiple MI. This usually results in the need for a heart transplant.

Question 27

What causes strokes?

Answer 27

Stroke is the death of an area of brain tissue usually caused by one of two factors:

1. Thrombus blocks an artery leading to the brain which reduces blood flow and starves brain tissue of oxygen.
2. Atherosclerosis and hypertension causing an artery leading to the brain to burst, cutting off blood supply of some brain tissue.

Question 28

What effects do strokes have?

Answer 28

• Numbness and weakness of face, arms and legs on one side of the body.
• Confusion, difficulty in speech and comprehension.
• Blurred vision.
• Difficulty in walking, balance and coordination.
• Severe and unexplained headache.

Question 29

How can CHD be treated?

Answer 29

1. Taking medication to lower blood pressure.
2. Taking medication to lower cholesterol level.
3. Open heart surgery to remove the plaque in coronary arteries.
   These measures are usually quite expensive, so people are encouraged to avoid CHD in the first place.

Question 30

What is arteriosclerosis?

Answer 30

Hardening and loss of elasticity of artery walls resulting from deposition of calcium and other mineral ions, especially in atheromas.

Question 31

What factors increase risk of CHD?

Answer 31

1. Age: Risk increases as age increases.
2. Gendre: Men are statistically more likely to die from CHD than women.
3. Smoking: Smoking increases risk of atherosclerosis and thrombosis.
4. Obesity: Obesity also increases risk of atherosclerosis due to LDLs.
5. Hypertension: Increases risk of atherosclerosis as well as haemorrhages.
6. High blood cholesterol: Encourages formation of LDLs which increases risk of atherosclerosis.
7. Diet: High saturated fats diet encourages formation of LDLs. High salt diet causes hypertension.
8. Genetics: Family history of CHD increases risk.
9. Diabetes: Causes hypertension which increases risk.
10. Stress: Encourages bad diet and hypertension.

Question 32

What is epidemiology?

Answer 32

The study of the distribution of a disease in populations, and the factors that influence its spread.

Question 33

What information can be gained from an epidemiological study?

Answer 33

• Which countries are at risk.
• Which parts of the population (age, gender) are at risk.
• Which lifestyle factors increase risk.

Question 34

What statistical evidence is there linking smoking and disease?

Answer 34

1. A regular smoker is 3 times more likely to die a premature death than a non smoker.
2. 50% of regular smokers are likely to die from smoking-related diseases.
3. The more cigarettes are smoked per day, the more likely and earlier a premature death will come.

Question 35

What evidence is there linking lung cancer to smoking?

Answer 35

1. A smoker is 18 times more likely to die from lung cancer than a non-smoker, heavy smokers are 25 times more likely.
2. 25% of smokers die from lung cancer.
3. The chances of dying from lung cancer reduces when you quit.

Question 36

What evidence is there linking COPD to smoking?

Answer 36

1. COPD is common amongst smokers but rare amongst non-smokers.
2. 98% of people with emphysema are smokers.
3. 20% of smokers have emphysema.

Question 37

What evidence is there linking CHD to smoking?

Answer 37

Evidence is less clear since CHD is a multifactorial disease. However, chemicals like nicotine encourage the mechanisms that lead to atherosclerosis and are therefore linked to CHD.