SB5 - Health, Disease And The Development Of Medicines

Question 1

What is health?

Answer 1

A state of ‘complete physical, social and mental well-being’

Question 2

What is physical, social and mental well-being?

Answer 2

Physical - being free from disease, sleeping well, regular exercise, limited intake of harmful substances such as alcohol or drugs
Social - how you get along with other people, how your surroundings affect you
Mental - how you feel about yourself

Question 3

What is disease?

Answer 3

A disease is a problem with a structure or process in the body which is not the result of injury.

Question 4

What are pathogens?

Answer 4

Pathogens are microorganisms which cause diseases.

Question 5

What are communicable diseases?

Answer 5

Diseases which are caused by pathogens and can be passed from one person to another.

Question 6

What are non-communicable diseases?

Answer 6

Diseases which cannot be passed from person to person. They are a result of a problem in the body, such as a fault in genes or lifestyle.

Question 7

What are deficiency diseases?

Answer 7

Malnutrition occurs when you get to little or too much of a certain nutrient. The lack of specific nutrients can cause defiency diseases.

Question 8

What is kwashiorkor + symptoms?

Answer 8

Deficiency disease caused by lack of protein. Symptoms include enlarged belly, small muscles and failure to grow properly.

Question 9

What is scurvy + symptoms?

Answer 9

Deficiency disease caused by lack of vitamin C. Symptoms include swelling and bleeding gums, joint and muscle pain and tiredness

Question 10

What is rickets/osteomalacia + symptoms?

Answer 10

Defiency disease caused by lack of vitamin D/calcium. Symptoms include soft bones and curved leg bones.

Question 11

What is anaemia +symptoms?

Answer 11

Deficiency disease caused by lack of iron. Symptoms include red blood cells that are smaller than normal and in reduced numbers and tiredness.

Question 12

Describe one way in which lifestyle choices may affect liver disease.

Answer 12

Taking a large amount of ethanol (found in alcohol) over a long period of time may lead to liver disease, including cirrhosis.

Question 13

What is cardiovascular disease?

Answer 13

Any disease which affects the heart and/or blood vessels. Non-communicable.

Question 14

How do you calculate body mass index (BMI)?

Answer 14

BMI = Mass(kg)/height^2(m)

Question 15

How do you calculate waist to hip ratio (WHR)?

Answer 15

WHR = Waist circumference (m) / hip circumference (m)

Question 16

What value of BMI and WHR is considered obese?

Answer 16

BMI of 30+ is obese
WHR of 1+ is obese

Question 17

Is BMI or WHR a better indicator of CVD risk and why?

Answer 17

WHR is better because it takes into account the location of body fat, whereas BMI does not. Visceral (abdominal) fat is closely related to CVD risk, but other types of subcutaneous fat are not, so WHR is a better indicator of CVD risk.

Question 18

What is angina?

Answer 18

Chest pain - usually an early indicator of other types of CVD

Question 19

What is atherosclerosis?

Answer 19

A build of of fatty deposit in the arteries

Question 20

What are strokes?

Answer 20

Where the blood supply to a part of the brain is cut off - often caused by blood clots.

Question 21

What are heart attacks?

Answer 21

Where blood flow to the heart muscle is suddenly blocked - often caused by blood clots

Question 22

How could smoking cause CVD?

Answer 22

Tobacco smoke contains many harmful substances which can damage the lungs when breathed in. Some of them are absorbed into the blood stream and can damage the artery lining. Fat builds up at the site of the damage, making the artery narrower. A blood clot may block the artery here, or break off and block the artery elsewhere, leading to a heart attack or stroke.

Question 23

Why is ‘prevention better than cure’ for CVD?

Answer 23

Methods of preventing CVD include stopping smoking, regular exercise and a diet with less fats and sugars, which are beneficial to all aspects of health. However, cures for CVD include surgeries, which carry risk of infection and heart failure and statins, a medication which must be taken for life and carries side effects such as headaches and kidney failure.

Question 24

How can lifestyle changes prevent CVD?

Answer 24

Lifestyle changes such as regular exercise, better diet (less fatty and sugary foods) and stopping smoking can prevent CVD from occuring. It is usually the first treatment method used. It is highly uninvasive and will benefit health, however it takes a long time and won’t help if you already have CVD.

Question 25

How can medication cure CVD?

Answer 25

Statins reduce the amount of blood cholestrol, which cures CVD as cholestrol narrows arteries. It will prolong life however it must be taken for life and has bad side effects such as headaches and kidney failure.
Aspirin is a blood thinner which prevents blood clots by reducing the ‘stickiness’ of the platelets. They will prolong life however they must be taken for life and if the user starts bleeding, it is much more difficult to stop the blood.

Question 26

How can surgeries cure CVD?

Answer 26

Stents - expandable mesh tubes which are placed in narrowed arteries to widen them and improve blood flow. They are a lifelong cure and the surgery is quick however there is a risk of infection and blood clots may develop near the stent.
Bypass - new pieces of healthy artery attached to circumvent damaged arteries and continue blood flow. This is a lifelong cure however the surgery is fairly complicated and there is a risk of infection.
Heart transplant - healthy donor heart replaces damaged heart. This will cure CVD however it is a very long and complicated surgery and there is a risk of infection and rejection, so the patient must take immunosuppressants for life, putting them at risk of other diseases.

Question 27

What are the two main factors which cause CVD?

Answer 27

obesity and smoking

Question 28

Describe the structure of a virus

Answer 28

All viruses contain one or more strands of genetic material surrounded by a protein coat (capsid), although many have additional layers surrounding the capsid.

Question 29

Describe the lytic cycle

Answer 29

Virus particles attach to a cell and inject their genetic material. The cell copies the viral genetic material and makes new viral genetic material and proteins. These components assemble into new viruses, which escape from the cell (some viruses cause the breakdown of the cell (lysis), others leave by pushing out through the cell membrane). This damages the cells, and causes disease. The viruses that have left the cell can infect other cells.

Question 30

Describe the lysogenic cycle

Answer 30

Sometimes, when a virus injects its genetic material into a cell, the genetic material inserts into the cell’s genetic material. Every time the cell divides, the virus’ genetic material is replicated alongside the cell’s. This happens many times. Sometimes, the viral genetic material separates form the cell’s genetic material and the lytic cycle is triggered.

Question 31

What is cholera (symptoms, spreading method, how to prevent spread)?

Answer 31

Cholera is a disease caused by the bacteria Vibrio cholerae. It affects humans by causing large amounts of watery diarrhoea (rice water) and dehydration. If untreated, death will occur in 2-4 days. It is spread by drinking contaminated water, on flies and on unwashed hands. Spread can be prevented by chlorinating water before drinking it and washing hands after using the toilet and before eating or preparing food.

Question 32

What is tuberculosis ((TB) symptoms, spreading methods, how to prevent the spread)?

Answer 32

Tuberculosis is a bacterial disease caused by the pathogen Mycobacterium tuberculosis. It affects humans by causing weight loss, a persistent cough and coughing up blood form the lungs. Also causes night sweats, loss of appetite, fever. Spread through the air. This can be prevented by opening windows in enclosed spaces and wearing face masks.

Question 33

What is chalara ash dieback (symptoms, spreading methods, how to prevent the spread)?

Answer 33

Chalara ash dieback is a fungal disease caused by the pathogen Hymenoschyphus fraxineus. It affects ash trees by causing death and wilting in leaves and branches and eventual tree death. It grows on fallen leaves and stems of ash trees and wind carries spores onto ash tree leaves. To prevent this, remove all ah tree litter from around the trees.

Question 34

What is malaria (symptoms, spreading method, how to prevent the spread)?

Answer 34

Malaria is a disease caused by the protozoan Plasmodium falciparum. It affects humans by causing a high fever, vomiting, hot+shivery, headaches, intense muscle pain, diarrhoea, possible coma and death. It is spread when mosquitos carrying malaria bite humans. To stop this, hang insecticide-treated mosquito nets over all beds and remove any stagnant water, get house sprayed with anti-mosquito products.

Question 35

What is AIDS ((aquired immunodeficiency syndrome) symptoms, spreading method, how to prevent the spread)?

Answer 35

AIDS is a condition caused by the virus HIV (human immunodeficiency virus). It affects humans by causing the destruction of helper T cells. Virus attacks the immune system so patients become immune compromised. In later stages, patients likely to die of secondary infections. The disease is spread though unprotected sex with an infected person or through direct contact of the blood of an infected person (such as when sharing drug needles). This can be prevented by not sharing needles, using barrier methods (such as condoms) every time you have sex, abstinence, HIV prevention medications).

Question 36

What is a stomach ulcer (symptoms, spreading method, how to prevent the spread)?

Answer 36

Stomach ulcers are caused by the bacteria Helicobacter pylori. It affects humans by causing a burning sensation in the stomach, can be associated with heartburn and indigestion. Spread by kissing infected people and consuming contaminated food/water. The spread can be prevented by not drinking more than 2 alcoholic drinks per day, not mixing alcohol with medicine, washing hands frequently, limiting use of aspirin, ibuprofen, naxprofen.

Question 37

What is Ebola (symptoms, spreading method, how to prevent the spread)?

Answer 37

Ebola is a disease caused by the virus Ebola haemorrhagic fever virus. It affects humans by causing sore throat, fever, vomiting, diarrhoea, rashes, bleeding internally and externally, has a mean death rate of about 50%. It is spread through eating raw or undercooked meat or contact with the bodily fluids of an infected person. Don’t touch people with Ebola, get infected people to a treatment centre, wash hands with soap and water frequently, quarantine those in close contact with an infected person.

Question 38

What is chlamydia (symptoms, spreading method, how to prevent the spread)?

Answer 38

Chlamydia is a disease caused by the bacteria Chlamydia trachomatis. It affects humans by causing some people pain when peeing, unusual discharges, unusual bleeding however most people are asymptomatic (which is why it spreads well). This can be prevented by getting tested for chlamydia and using condoms when having sex.

Question 39

What are some physical defences of plants?

Answer 39

Waxy cuticle - covers leaves and makes it difficult for pathogens to enter the leaf
Bark - layers of dead cells protect their stems with thick bark
Thorns - deter herbivores
Leaves that droop or curl when touched - deter herbivores

Question 40

What are some chemical defences of plants?

Answer 40

Poisons - some plants produce poisons to deter herbivores and pathogens (e.g. foxgloves produce a poison which affects the heart rate of animals that feed on it)
Distress signals - some plants use chemicals as distress signals to other plants to warn them of danger in the area.
Antiseptics - many plants have antibiotic/antiseptic properties which kill pathogens

Question 41

What are the ways to identify plant disease?

Answer 41

Observing symptoms and comparing them to those from a gardening manual or website.
Sending samples of the diseased plant to a plant pathologist, who will analyse it under a microscope or do DNA analysis to test for certain diseases.
Trial and error - if you think the plant has a fungal infection, spray it with fungicide, if this doesn’t fix it, try something else.
Distribution analysis - helps track the spread of the disease.

Question 42

What are some symptoms of plant disease?

Answer 42

Discolouration, stunted growth, abnormal growths, lesions (areas of damage), wilting.

Question 43

What are some physical defences of humans against disease?

Answer 43

The skin covers most of the body and stops pathogens getting inside the body. The nose has hairs which trap pathogens. Mucus is produced, which traps pathogens and ciliated epithelial cells waft the mucus up the trachea to be swallowed.

Question 44

What are some chemical defences of humans against disease?

Answer 44

The stomach contains hydrochloric acid which kills any pathogens caught in the mucus. Tears contain lysozymes which are enzymes which destroy bacterial cells by breaking down their cell walls.

Question 45

What is an antigen?

Answer 45

Antigens are molecules on the surface of cells or virus particles which can be used by the immune system to identify if something inside the body is foreign.

Question 46

Explain the production of antibodies.

Answer 46

Pathogens have antigens on their surface which are unique to them. Some lymphocytes become activated as they have antibodies which fit with the antigen of the pathogen. The activated lymphocytes divide rapidly and some secrete many antibodies which bind to and destroy pathogens. Some of the lymphocytes created remain in the blood as memory lymphocytes so that if they are ever infected with the same pathogen again, the response will be much quicker.

Question 47

Why is the primary response slower than the secondary response?

Answer 47

In the primary response, the lymphocytes must first undergo clonal selection (choosing the right lymphocytes which produce the antibodies needed) and then clonal expansion (lymphocytes dividing). Many fewer antibodies are produced in the primary response. However, in the secondary response, some memory lymphocytes already exist, so they immediately begin dividing and lots of antibodies are produced quickly, so the person feels less sick.

Question 48

What is phagocytosis?

Answer 48

Macrophages locate pathogens. They then engulf and digest them.

Question 49

Why are antitoxins produced?

Answer 49

Some pathogens secrete toxins which could be harmful to our bodies, so our lymphocytes produce antitoxins to neutralise the toxins and ensure they will not do us any damage.

Question 50

How do vaccines give people immunity without making people sick?

Answer 50

Vaccines contain weakened or inactive versions of the pathogens, meaning that the person does not get sick. They contain the same antigens as the real pathogen, so an immune response is triggered. This causes the production of antibodies and memory lymphocytes. This means that if the person is infected with that pathogen, a secondary response will be triggered and they will not feel sick as the response is much faster.

Question 51

What is herd immunity?

Answer 51

When a large proportion of a population has been vaccinated, then those that aren’t vaccinated are protected because they are unlikely to come into contact with an infected person, as the pathogen finds it difficult to spread throughout the population.

Question 52

How do antibiotics work?

Answer 52

Many antibiotics work by damaging the cell wall of bacteria, causing them to die. Others work by damaging the bacterium’s DNA.

Question 53

How do new medicines get tested?

Answer 53

First, it is tested on cells and tissues in a lab. Then, if this is successful, it is tested on live animals. Then, if that was successful, it can be tested on humans (healthy volunteers) then people afflicted with the disease.

Question 54

What are you looking for in a clinical trial?

Answer 54

Efficacy - how well the drug works
Toxicity - what side effects the drug produces, how safe is it
Dosage - how much should you give to patients

Question 55

Core practical - antibiotics

Answer 55

• prepare an agar plate with a bacterial lawn using aseptic technique
• mark the bottom of the plate in sections, label each one with the antibiotic you are using and one for control
• sterilise the forceps and use them to place one antibiotic disc n the correct section
  -repeat for other discs
• tape the lid on
• after incubated, measure the diameter of the clear space around each disc. Work out the area of each space.
• draw a graph of your results.

Question 56

What are monoclonal antibodies and how are they produced?

Answer 56

Monoclonal antibodies are antibodies produced by hybridoma cells. They are produced by injecting an antigen into a mouse, which will produce lymphocytes against the antigen. The lymphocytes are extracted. Myeloma (cancer) cells are grown and extracted. The cancer cells and lymphocytes are fused to form hybridoma cells, which both produce antibodies and continue dividing forever.

Question 57

How can monoclonal antibodies be used in cancer treatments?

Answer 57

Chemotherapy drugs can be attached to monoclonal antibodies so that only the cells that need treating are damaged.

Question 58

How do pregnancy tests work?

Answer 58

They work by detecting a hormone only produced during pregnancy (hCG). This happens because there are monoclonal antibodies on the test strip, which will bind to the hormone if present. This will cause a dye to be released, which produces a line showing that the woman is pregnant.