4.1.1 - Communicable Disease (set C - Preventing And Treating Disease)

Question 1

What are autoimmune diseases?

Answer 1

When immune system stops recognising ‘self’ cells and starts to attack healthy body tissue - numerous reasons why this is believed to happen (eg abnormal T regulator cells)

Eg arthritis

• immunosuppressant drugs can be used as treatments

Question 2

Outline the autoimmune disease arthritis?

Answer 2

• affects the joints especially the hands,wrists and ankles

No cure however treatments involved anti-inflammatory drugs, steroids and pain relief

Question 3

Outline the autoimmune disease type 1 diabetes?

Answer 3

Affects the insulin-secreting cells of the pancreas

• treatment involved insulin injections and pancreas transplants

Question 4

Explain the 2 forms of natural immunity?

Answer 4

• natural active immunity
• natural passive immunity

Question 5

Outline natural active immunity?

Answer 5

When your body encounters a pathogen the immune system produces T and B memory cells so if you encounter the pathogen again you can quickly recognise the antigens and destroy the pathogen

• active as body produces antibodies and memory cells

Question 6

Outline natural passive immunity?

Answer 6

Baby’s immune system can not make antibodies - system developed which allows antibodies from mother to cross placenta to fetus

• first milk mother makes is called colostrum which is very high in antibodies which can pass into infants blood without being digested

Question 7

Outline artificial passive immunity - provide an example?

Answer 7

For certain potentially fatal diseases, antibodies are formed in one individual and extracted, and injected into the blood stream of another - gives temporary immunity and can save the individuals life

• for example someone infected with tetanus will experience muscle spasms, difficulty breathing and swallowing - treated by tetanus antibodies extracted from a horses bloodstream

Question 8

Outline artificial active immunity - provide an example?

Answer 8

The immune system of the body is stimulated to make its own antibodies to a safe form of an antigen when injected into the bloodstream eg through a vaccine

• antigen is usually not the normal live pathogen (could result in disease) but instead the pathogen is made safe, eg its weakened (attenuated)

Question 9

explain how vaccines can be used to provide artificial active immunity?

Answer 9

Vaccines may contain killed or inactive pathogens, attenuated (weakened) strains of live bacteria of viruses or toxin molecules extracted form the pathogen

injected into bloodstream and stimulates production of antibodies

Question 10

Explain ways the pathogen is made safe and reduces risk of infection - explain what vaccines contain - give examples?

Answer 10

• killed or inactivated bacteria and viruses - eg whooping cough
• attenuated strains of live bacteria or viruses - eg rubella
• toxic molecules which have been altered and detoxified - tetanus
• genetically engineered antigens - eg hepatitis B vaccine

Question 11

Outline how vaccines work?

Answer 11

1) pathogen made safe by a number of ways - so that the antigens are intact but do not risk infection

2) small amounts of safe antigen are injected into blood

3) primary immune response is triggered by foreign antigens - body produces antibodies and memory cells

4) if you come into contact with live pathogen again than secondary immune response is triggered and pathogen is destroyed rapidly

Question 12

Explain what an epidemic is?

Answer 12

When a communicable disease spreads rapidly to a lot of people at a local or national level

• can be prevented by mass vaccination

Question 13

Explain what a pandemic is - why can they be hard to combat?

Answer 13

When a communicable disease spreads rapidly across a number of countries and continents - some can not be prevented by vaccinations

• for example malaria - protoctist that causes malaria spends time inside erythrocytes (protected by self antigens)
• HIV enters macrophages and T helper cells - disables the immune system itself

Question 14

Outline the sources of medicines, explain what they treat - give 3 examples?

Answer 14

• pencillin - comes from mould - effective at treating bacterial diseases
• aspirin - comes from willow bark - painkiller and anti-inflammatory
• digoxin - extracted from foxgloves - strong heart drug used to treat atrial fibrillation/heart failure

Question 15

Explain the importance of maintaining biodiversity regarding medicine?

Answer 15

Important we don’t destroy plants, animals or microorganisms which could provide key life-saving drugs

• lots of current drugs come from these sources - scientists yet to explore majority of life on earth

Question 16

Outline the role of pharmacogenetics as a possible source of medicine - provide an example?

Answer 16

Personalised medicine which work with your individual combination of genetics and disease

• human genome can be analysed which can give and understanding of the genetic basis of a disease - eg 30% of breast cancer caused by mutation in HER2 gene - activity of this gene could be shut down by specific drug

Question 17

Explain the role of synthetic biology for treating disease?

Answer 17

Using genetic engineering we can develop populations of bacteria to produce needed drugs that would be too rare, too expensive or not available

Question 18

Outline the problem regarding antibiotics?

Answer 18

Antibiotics have been widely prescribed for many patients even if the infection is minor and could be dealt with my their immune system

• has led to them becoming less effective due to bacteria becoming more resistant

Question 19

Outline how bacteria becomes resistant to antibiotics?

Answer 19

population with no antibiotic-resistant bacteria - experiences a chance mutation in one bacterium which produces a gene for antibiotic resistance

Antibiotic-resistant bacteria survives antibiotics and reproduces - passing on the resistant mutation

• bacteria reproduce rapidly - once mutation occurs not long before big population of antibiotic-resistant bacteria

Question 20

Explain how agriculture is impacting antibiotic resistance?

Answer 20

farmers routinely add antibiotics to animal feed - this accelerates natural selection of antibiotic-resistant strains of both humans and animal pathogen

Question 21

Explain the types of antibiotics?

Answer 21

bactericidal (they kill) or bacteriostatic (they inhibit growth processes) - do this by targeting prokaryotic features

Question 22

Outline the ways of reducing antibiotic resistance - give 5 points and explain them?

Answer 22

• Tighter controls in countries in which antibiotics are sold without a doctor’s prescription
• Doctors avoiding the overuse of antibiotics, prescribing them only when essential and making sure they are the correct ones
• When prescribed a course of antibiotics, the patient finishing the entire course (even if they feel better after a few days) so that all the bacteria are killed, and none are left to mutate to become resistant strains
• The use of ‘wide-spectrum’ antibiotics being reduced and instead those antibiotics that are highly specific to the infection (‘narrow-spectrum’ antibiotics) being used
• The type of antibiotics prescribed being changed so that the same antibiotic is not always prescribed for the same infections and diseases (this reduces the chance of a resistant strain developing)

Question 23

Explain how the spread of already-resistant strains can be limited?

Answer 23

• ensuring good hygiene practices such as handwashing and the use of hand sanitisers (this has reduced the rates of resistant strains of bacteria, such as MRSA, in hospitals)
• isolating infected patients to prevent the spread of resistant strains, in particular in surgical wards where MRSA can infect surgical wounds

Question 24

Explain 3 factors causing antibiotic resistance?

Answer 24

• Overuse of antibiotics and antibiotics being prescribed when not necessary
• Large scale use of antibiotics in farming to prevent disease when livestock are kept in close quarters, even when animals are not sick
• Patients failing to complete the full course of antibiotics prescribed by doctors