2.6 Health, Disease, Defence and Treatments ❤️‍🩹

Communicable disease

contagious, microorganism passed from one organism to another

Non-communicable disease

not contagious, caused by lifestyle or genetic abnormalities

Healthy

person free from both types of disease

Microorganism

bacteria, virus, fungus

Cost to soceity

• unhealthy people may not be able to work and require healthcare

• NHS spends large amount on treating diseases e.g medicine, staff, hospital care

• long term treatment e.g stays in hospital for cancer

Examples of viruses

HIV (leads to aids), cold/flu, human papilloma virus (HPV)

Cause, prevention and treatment of HIV/ AIDS

• exchange of body fluids during sex, infected blood

• using a condom, not sharing needles

• controlled by drugs

Cause and prevention of cold/ flu

• airborne (droplet infection)

• flu vaccination

Cause and prevention of HPV

• sexual contact

• HPV vaccine at 12-13, also prevents cervical cancer

Examples of bacterium

salmonella food poisoning, tuberculosis, chlamydia

Cause, prevention and treatment of salmonella food poisoning

• contaminated food

• cook thoroughly, prevent cross contamination

• antibiotics

Cause and treatment of tuberculosis

• airborne (droplet infection)

• antibiotics

Cause, prevention and treatment of chlamydia

• sexual contact

• using a condom

• antibiotics

Examples of fungus

athlete’s foot, potato blight

Cause, prevention and treatment of athlete’s foot

• contact

• avoid direct contact with spores (flip flops)

• anti-fungal treatment

Cause, prevention and treatment of potato blight

• spores spread in air from plant to plant (especially when warm and humid)

• crop rotation

• fungicide

Droplet infection

microorganisms released into air when infected person coughs, sneezes, or talks

Aseptic techniques

procedures carried out to prevent the contamination of pure cultures of microorganisms

Defence mechanisms against entry

• skin barrier to microorganisms

• mucous membranes in nose, ears and eyes to trap microorganisms

• blood clotting, to stop it escaping and prevent entry where skin is damaged

Antigen

marker on cell/ pathogen surface with specific shape

Need for antigens

allows antibodies to be produced that are complementary in shape

Lymphocytes

produce antibodies which immobilise microorganisms by clumping them together

Purpose of immobilising microorganisms

reduces symptoms and prevents spread of infection/ reproduction, can be ingested easier

Phagocytosis

phagocyte engulfs and digests microorganisms using enzymes

Fighting pathogens process

1. lymphocyte recognises pathogen by antigens and produces complementary antibodies

2. antibodies bind and cause them to clump together, prevents spread and easier to kill

3. phagocytosis, they engulf and digest microorganisms with enzymes

Primary response

lymphocytes work to produce antibodies, person feels sick

Secondary response

memory lymphocytes, prevents person getting sick again, now immune

Memory lymphocytes

remain in body for very long time, respond quickly and produce antibodies if body is infected by same microorganism

Immunity

enough antibodies for body to fight off disease and prevent getting sick

Active immunity

when body’s lymphocytes are activated and produce specific antibodies needed to fight pathogen

Features of active immunity

• slow acting

• long lasting protection

Natural active immunity

primary response when microorganism enters

Artificial active immunity

vaccines

Passive immunity

when ready made antibodies from another source are introduced to body

Features of passive immunity

• slow acting

• short term protection (no memory lymphocytes)

Natural passive immunity

breastfeeding passes on the antibodies from mother/ across placenta

Artificial passive immunity

anti venom used after a poisonous bite

Vaccine

injection of dead or weakened pathogens

Why do pathogens need to be dead or weakened

otherwise would give you disease it is trying to prevent

How do vaccines work

stimulate immune system to produce antibodies and create memory cells

Purpose of vaccines

memory lymphocytes will produce large numbers of antibodies very quickly, wont get sick

Booster vaccine

needed to increase/ maintain high levels of antibodies for immunity long term

Effect of booster vaccines

rapid antibody response due to memory lymphocytes to prevent losing immunity

Plant defence mechanisms

• waxy cuticles prevent microorganisms entering/ leaving and thick cell walls surround

• produce antimicrobial chemicals to kill or inhibit growth of bacteria/ fungi e.g mint

• poisonous chemicals to deter herbivores from eating e.g digitalis from foxglove

Antibiotics

chemicals produced by fungi used against bacterial diseases to kill or reduce their growth

History of penicillin

1. first ever antibiotic

2. discovered by Alexander Fleming in 1920’s after he noticed bacteria didn’t grow near a mould contaminating his cultures

3. concluded mould released a substance preventing bacterial growth

4. scientists Florey and Chain produces pure penicillin in 1940’s and began large scale production

5. many have been discovered since, grown in carefully controlled conditions in fermenters

Preclinical trials

• conducted in laboratories

• tested on cells, tissues and animals

• check if drug is toxic and effectiveness

Clinical trials

• tested on small number of healthy volunteers, then more

• to find optimum dosage with balance with minimal side effects

• eventually tested on sick to ensure it works

Peer review

• research is reviewed by other scientists before publication

• ensures findings are valid, reliable and meet standards with feedback

• drug can then be licensed for use

Advantages of animal testing

• Avoids testing on humans at this stage

• Can check for side effects in living organisms

Disadvantages of animal testing

• Animals are different from humans, so drug may react differently

• Raises ethical issues

More effective antibiotic

larger clear zone

Antibiotic resistance

drugs can no longer kill the bacteria, caused by their overuse

Antibiotic resistance process (natural selection)

1. variation among phenotypes of bacteria, some are resistant to antibiotics

2. treating with antibiotics provides competition

3. resistant individuals survive, less resistant don’t (differential survival)

4. resistant bacteria reproduce and pass on resistance gene to next generation

5. number of resistant bacteria increase

Superbug

resistant to multiple antibiotics so infections are difficult to treat e.g MRSA

Reducing superbugs

1. hygiene, regular handwashing and cleaning hospital environments

2. controlled antibiotic use, prescribe only when necessary

3. isolation, keep patients infected separate to prevent spread

Why superbugs are hard to eradicate

• bacteria can mutate quickly

• resistant strains survive and multiply

• limited development of new antibiotics

Inheritance of non communicable diseases

some people carry a gene that predisposes them to conditions

Lifestyle factors of non communicable diseases

• poor diet

• lack of exercise

• overexposure to sun

• misuse of drugs

Poor diet effects

• eating too much sugar and fat can cause obesity

• may lead to cardiovascular disease or type 2 diabetes

• unbalanced diet means missing out on essential vitamins and minerals

Lack of exercise effects

• taking in more energy than they use can cause obesity

• exercise is needed to strengthen bones and heart/ improve mood

Overexposure to sun effects

• too much UV radiation can cause mutations in skin

• may lead to skin cancer

• very preventable, less time in sun or using sunscreen

Misuse of drugs, alcohol

• unlikely to cause harm in moderation

• binge drinking (large amount in short period) can damage liver and organs

• drinking during pregnancy causes serious brain damage to foetus, foetal alcohol syndrome

Misuse of drugs, tobacco

• Tar causes bronchitis, narrow bronchi and bronchioles

• also causes emphysema which damages alveoli and reduces surface area for gas exchange

• leads to lung cancer/ abnormal cell division

• nicotine is addictive and affects heart rate

• carbon monoxide combines with haemoglobin and reduces oxygen capacity

Build up of cholesterol in arteries

causes them to become narrow, restricting blood flow

Heart attack/ CHD

build up of cholesterol in coronary arteries

Stroke

build up of cholesterol in brain

Heart attack/ CHD process

1. cholesterol builds up in coronary artery

2. becomes narrow as blockage/ clot forms

3. blood flow is restricted

4. heart muscle is starved of glucose and oxygen

5. respiration is reduced/ stopped and heart cells die

Stroke process

1. cholesterol builds up in artery in brain

2. becomes narrow as blockage/ clot forms

3. blood flow is restricted

4. part of brain is starved of glucose and oxygen

5. respiration is reduced/ stopped and brain cells die, reduced brain function e.g paralysis

Decreasing risk of cholesterol buildup

• healthy diet

• regular exercise

• managing stress

• avoid smoking

Treating heart attack and strokes

angioplasty to widen arteries and drugs such as statins or aspirin to prevent

Angioplasty

• balloon inserted into blocked artery and inflated to expand wire cage/ artery

• stent (mesh tube) placed, balloon removed, to keep open and restore blood flow

Statins

lower blood cholesterol levels

Aspirin

reduces blood clotting to prevent blockages, thinner and less sticky

Cancer

uncontrolled cell division that can lead to development of a tumour

Benign

encapsulated, surrounded by boundary so does not spread

Malignant

not encapsulated, spreads via blood causing secondary tumours so far more dangerous

Lifestyle factors in cancer

• cervical cancer, reduced with HPV vaccine

• lung cancer, increased by smoking (carcinogens)

• skin cancer, increased by tanning/ excessive sun exposure

Early detection

via screening programs, improves chances of treatment and recovery

Importance of early detection

tumour may be smaller and not have spread, significantly increasing survival rates

Treatments of cancer

surgery, radiotherapy, chemotherapy and immunotherapy

Treating cancer with surgery

1. physically removes cancer cells

2. few side effects

3. will not work if spread or inaccessible

Treating cancer with radiotherapy

1. x rays or radiation to kill cancer cells

2. target cells deep in body, accurate

3. damages healthy cells too

Treating cancer with chemotherapy

1. using drugs to kill cancer cells

2. target cells anywhere, good if spread

3. lots of side effects e.g hair loss, weak immunity

Treating cancer with immunotherapy

1. injecting antibodies which attach to cancer cells and allow immune system to kill

2. fewer side effects and doesn’t harm healthy cells

3. not suitable for all cancer types