Disease

Name the 4 main types of pathogens

• Viruses

• Bacteria

• Fungi

• Protists

How are communicable diseases spread?

• Direct contact

• Water

• Through air (e.g. sneezing)

• Unhygienic food preparation

• Vector- any organism that can spread disease

Give 3 examples of viral diseases

• Tobacco mosaic disease (TMV)

• HIV/AIDS

• Measles

What is TMV?

TMV is a plant disease which is spread from contact between plants or a farmer's hands.

It infects the chloroplasts of plant leaves and changes their colour from green → yellow or white in a mosaic pattern

↳ Reduces the plant's ability to photosynthesise and grow properly → reduces crop yield

What is human immunodeficiency virus? What does it do?

HIV is an STI which is spread from by unprotected sex but also from: cuts, sharing needles, and breast milk.

An infected individual will experience flu-like symptoms which pass so many do not know they are infected.

Months or years after the infection, HIV can develop into AIDS which attacks the patient's immune system

What is measles?

A viral disease, usually caught by young people.

It is transmitted through the air and can cause fever and skin rashes.

Fortunately, there is a vaccine

Name the 2 bacterial diseases

• Gonorrhoea

• Salmonella

What is gonorrhoea? What are the symptoms and treatments?

Gonorrhoea is an STD caused by bacteria

Symptons include:

• Pain whilst urinating

• Thick yellow/green discharge from the vag/pp

Treatment- antibiotics BUT they are becoming resistant

What is salmonella? What are the symptoms?

A bacteria which causes food poisoning so poultry are vaccinated

Symptoms:

• Fever

• Stomach cramps

• Vomitting

• Diarrhoea

What is malaria? What are the symptoms?

Malaria is a protist disease spread by mosquitos which suck blood from an infected person.

The protist then asexually reproduces in the liver

Symptoms:

• Fever

• Sweats and chills

• Vomitting

• Diarrhoea

Name 2 examples of fungal disease

• Athlete's foot

• Rose black spot

What is rose black spot?

Rose black spot is a plant disease which infects the leaves and cause black/purple spots on leaves and turn the rest of the plant yellow.

↳ Reduces the ability to photosynthesise therefore stunting growth

Transmitted by:

• The air

• Water

• Direct contact from gardeners

Treated using fungicides

How can the spread of communicable diseases be prevented?

• Personal hygiene

• Sterilising water

• Vaccination

• Contraception

What are antibodies?

Lymphocytes which engulf pathogens and destroy them

What are memory cells?

Lymphocytes which become memory cells can ‘remember' how to make a specific antibody for the same pathogen, making the immune response faster

What is an antigen?

Antigens are ‘markers' which bind to an antibody and are unique for each pathogen, allowing the immune system to distinguish between each pathogen

What are anti-toxins?

Specialised antibodies which bind to a toxin produced by a pathogen and neutralising it

*They do NOT kill the pathogen

Describe antibiotic resistance

Bacteria can mutate and become resistant to antibiotics so the population of resistant bacteria increases due to natural selection and continue to rapidly reproduce

What are the risk factors for non-communicable diseases?

• Smoking

• Diet

• Physical inactivity

• Alcohol/drugs

• Stress

What is cancer?

The uncontrollable growth and division of cells

Name the 2 types of tumours. What are the similarities and diferences?

Benign- Grows slowly; usually grows within a membrane, so can easily be removed; does not invade other parts of the body

Malignant- Grows quickly; invades neighbouring tissues and can spread to other parts of the body in the bloodstream; as the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body - this is called metastasis.

What causes cancer?

• Genetics

• Carcinogens- chemicals and other agents which cause cancer

  ↳ They damage DNA, causing mutations

• Smoking/Alcohol

• UV radiation

• Diet

How does smoking increase the risk of cardiovascular disease?

• damages the lining of the arteries

  ↳ Causes build up of fatty material

• Inhalation of carbon monoxide

  ↳ reduces the amount of oxygen that can be carried by the blood

• Nicotine increases heart rate

  ↳ heart strain

How does smoking increase the risk of pulmonary disease?

• Damages the bronchioles

  ↳ Destroys many alveoli

• Inflamed airways

  ↳ Mucus build up

• Patient becomes breathless

  ↳ Unable to obtain oxygen required for respiration

What are the human and financial cost of non-communicable diseases to an individual, a local community, a nation or globally

Human: - shorter life expectancy, reduced quality of life, high medical expenses, loss of income if unable to work, Increased cost of living due to adaptations

Community- Pressure on local healthcare systems, strain on community healthcare budgets

Nation- High mortality rates, economic lossed due to reduced productivity, high investment in public health

Globally- High death rats, health inequalities between high and low income countries

What are the effects of smoking on babies?

• Increases the chance of miscarriage

• More likely to suffer from asthma

• The physical and intellectual development of the baby is affected

• Increase risk of birth defects

What are the effects of alcohol on the liver?

• Lipids build up in the liver

• Leads to alcoholic poisoning

• Cirrhosis- scarring of the liver → loses its ability to function

• Reduced ability to process alcohol

What are the effects of alcohol on the brain?

• Slows reaction time

• Difficulty walking

• Impaired memory

• Slurred speech

• Changes in sleep patterns and mood

• Psychiatric problems

What are the effects of alcohol on unborn babies?

• Smaller in size

• Smaller brain with fewer neurones

• Long term learning and behavioural difficulties

Describe why being obese increases the risk of type 2 diabetes

Being obese means that there are more deposits of lipids in the abdomen which can cause the body's cells to become sensitive to insulin

↳ Harder for the cells to absorb glucose, therefore resulting in high blood sugar

How does having coronary heart disease increase the risk of a heart attack?

• Build up of fatty plaque in the coronary artery

  ↳ Artery becomes blocked so there is a reduced blood flow to the heart

  ↳ Heart muscle dosen't receive oxygen and glucose needed for respiration

  ↳ Heart muscle can no longer contract

• Heart attack occurs

How can cardiovascular disease be treated?

• Statins

• Stents

• Heart transplants

• Artificial heart

How can drugs be used to treat coronary heart disease?

Statins lower chlorestrol in blood by lowering the production in the liver

↳ Patients can experience bad side effects such as: headaches, memory loss, liver damage

How are stents used to treat cardiovascular disease?

Stents are inserted to the coronary artery to open them up and maintain blood flow

How can a heart transplant be used to treat cardiovascular disease?

When a patient goes into heart failure, then the heart is unable to pump sufficient oxygen around the body

↳ There are a shortage of donor hearts

↳ Patients must take immunosupressant drugs in order to prevent their body from rejecting the heart → higher risk of infection

Explain how vaccines work

• Weakened or dead forms of a pathogen enter the body

• This stimulates the white blood cells to produce antibodies

• Memory cells are formed so that they can recognise and respond quickly to the same pathogen

How does the nose defend against pathogens?

• The nose has internal hairs, which act as a physical barrier to infection

• Produces mucus

  ↳ Traps pathogens before they can enter the lungs → when you blow yoour nose, mucus is removed and so are any pathogens trapped within it

In what order are drugs developed?

• Computer simulation

• Cells

• Tissues

• Animals

• Healthy volunteers

• Patients

What is the difference between a blind trial and double blind trial?

Blind trial- researchers know which is the placebo but the volunteers don't

Double blind trial- both the volunteers and researchers don't know which is the placebo

What are monoclonal antibodies?

Identical copies of one type of antibody

Describe the formation of monoclonal antibodies

1. An antigen is injected into a mouse

2. This triggers the production of lymphocytes which produce specific antibodies

3. Spleen cells are extracted as they produce the lymphocytes

4. Lymphocytes are fused with cancer cells called myeloma cells to form hybridoma cells

5. These divide and multiply rapidly to produce millions of monoclonal antibodies specific to that antigen

What are the uses of monoclonal antibodies?

• Pregnancy tests

  ↳ They bind with a hormone called HCG → only found in the urine of pregnant women

  ↳ HCG will bind to the monoclonal antibodies on the test stick → change in colour or pattern

• Cancer diagnosis and treatment

  ↳ Cancerous cells have antigens → monoclonal antibodies can bind specifically with these antigens

  ↳ monoclonal antibodies will bind with these cancer cells and clump them together → easier to identify a cancerous tumour

What are the benefits and limitations of monoclonal antibodies?

Benefits:

• Test for pregnancy

• Test for STD

• Treat cancers - carry drugs directly to the tumour

Limitations:

• Unwanted side effects

• Expensive to produce

• Requires the use of animals → unethical