Topic 5 - Health and Disease ✅

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What is health according to W.H.O.

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

• Not just the absence of disease

What is the difference between communicable and non communicable diseases?

• Communicable diseases are passed directly between individuals

  • Caused by a pathogen

• Non communicable diseases cannot be transmitted between induvial

  • Generally long-lasting

  • Caused by lifestyle and genetics

Why does having one diseases lead to higher susceptibility of other diseases  

• A disease may weaken an individual's immune system, making you more susceptible to other diseases

What is a pathogen

A disease causing organism

Example (4) of pathogen

• Virus

• Bacteria

• Fungi

• Protist

Describe cholera

• Caused by bacteria

• Spread by drinking water that has been contaminated with infectious faeces

• Causes diarrhoea

How can cholera be reduced

• More access to clean water

• Improved sanitation

Describe tuberculosis

• Caused by bacteria

• Airborne

• Causes lung damage

How to reduce the spread of tuberculosis

• Improved hygiene and ventilation

• Infected individuals should avoid crowded areas

Describe chalara ash dieback

• Caused by fungus

• Spread airborne by spores

• Causes blackened leaves and bark lesions

How to reduce chalara ash dieback

• Kill infected plants

• Control movement of ash trees

Describe malaria

• Caused by protists

• Spread by mosquito vectors

• Causes damage to blood and liver

How can malaria be reduced

• Mosquito nets

• Insect repellent

Describe sotmach ulcers

• Caused by bacteria called Helicobacter

• Transmitted orally by eating infected food

• Causes stomach pain and vomiting

How to reduce stomach ulcers

Improve hygiene and sanitation

Describe ebola

• Caused by virus

• Spread by bodily fluids like blood, semen, saliva

• Causes haemorrhagic fever

How to reduce ebola

• Improve hygiene

• Isolate infected individuals

Describe HIV

• Caused by a virus

• Spread by bodily fluids during unprotected sex, injecting drugs using unsterilised needles

• Causes white blood cells to get destroyed, leading to AIDS

How to reduce HIV

• Do not have sex

• Do not share needles

• Wear a condom

 Can viruses survive outside of their host

• They need the host cell to reproduce

• This can be done in a lytic pathway or a lysogenic pathway

 What is the lytic pathway

• Using host cell machinery, the virus replicates its DNA

• These are assembled to form new virus particles

• When the host cell is full of virus particles, it bursts, in a process called lysis

• The process is then repeated with nearby cells

What is the lysogenic pathway

• The virus uses enzymes to insert its DNA into the host cell DNA

• The host cell replicates, and the DNA of the virus is also copied during this process

• The lytic cycle begins at this point, starting with the assembly of new viral particles

 

how are STIs spread

• Through sexual contact

• They are carried in bodily fluids such as semen and vaginal fluid

 

how can chlamydia and HIV be reduced

• Barrier methods of contraception e.g. Condom

• Not having sex

 how do plants protect themselves from pests and pathogens using physical barriers 

• They can use a cellulose cell wall, which is impermeable to many pathogens

• Or a waxy cuticle on the surface of the leaf, which acts as a barrier to most pathogens

how do plants protect themselves from pests and pathogens using chemical barriers

• Cells of some plants produce antimicrobial chemicals

• Some plants release compounds that attract large insects

  • These feed on the pests and stop them from eating the plant

• Humans can extract antimicrobial compounds for these plants to use in medicine and antibiotics

how can plant diseases be detected in the field

• Using visible cues

  • Chalara ash dieback causes malformations and browning of leaves

  • Aphids causes serious structural damage

  • Tobacco mosaic virus causes discolouration of leaves

5.11 - how can plant diseases be detected in the lab

• Use this method -

  • Cuttings are taken from diseased plant

  • The virus causing the disease is grown on an agar plate

  • The pathogen is tested and identified using a monoclonal antibody testing kit

 

What are the physical barriers the human body provides

 

• Mucus, cilia and skin

 

How does mucus protect us

• Produced by goblet cells in the airway

• Mucus traps bacteria and other pathogens before they reach the lungs and cause infection

 

How does cilia protect us

• Cilia waft away mucus that has trapped pathogens

• to be killed by stomach acid

How does skin protect us

• Skin cells provide a physical barrier against pathogens

• Protecting the tissues and cells beneath it from infection

 

What are the chemical barriers our bodies have

• Lysozymes

• Hydrochloric acid

 

How do lysozymes protect us

• Used by white blood cells to kill and digest bacteria

How does hydrochloric acid protect us

• Used to kill bacteria in food that reaches the stomach

• Prevents infection

 

5.14 - How does the body respond to an immunisation

• In vaccines there is a weakened or dead version of the pathogen

• There are antigens on these pathogens

• Your body creates antibodies to destroy thee antigens

• The antibodies attach to the antigens, meaning the antigens can't harm your body

• As your body makes antibodies to fight the pathogen's antigens, it also makes memory cells

• This means when your body gets the actual pathogen (not dead or weakened version), the memory cells will know how to fight the pathogen

Advantages of immunisation

• Has evidence of eradicating many diseases so far

• Immunisation leads to herd immunity, preventing epidemics

 

Disadvantages of immunisation

• There can be side effects like fevers

 

What is herd immunity

• When people are vaccinated it increases the percentage of the population that is immune

• The few people that are unvaccinated are then less likely to catch the disease, since the chance of contacting someone infected is low

5.16 - what are antibiotics used to treat + why

• Bacterial infections

• Because they inhibit cell processes in the bacterium but not the host organism

 

 

Name 3 aseptic techniques

• Use of an autoclave to prepare sterile growth medium and petri dish

• Use of a sterile inoculating loop to transfer microorganisms

• The need to keep petri dishes and culture vials covered

formula for cross sectional area of agar jelly

Pi x r²

What does the process of developing new medicines include:

• Many stages e.g.

  • Discovery

  • Development

  • Preclinical testing

  • Clinical testing

5.21 - how are monoclonal antibodies made 

• The rat is injected with antigens.

• Then it makes lymphocytes, which make antibodies to fight the antigens.

• The cells are taken out of the rat. In a lab, cancer cells are added to the cell.

• The cancer cell fuses with the lymphocyte to make a hybridoma cell.

• The hybridoma cells copy themselves and produce antibodies.

• The antibodies are called monoclonal antibodies because they came from a single cloned cell.

• The monoclonal antibodies are created to be harvested and used for different purposes.

How are monoclonal antibodies used in pregnancy testing

• Pregnancy test kits use monoclonal antibodies.

• These have been designed to bind with a hormone called HCG which is found only in the urine of pregnant women.

• Monoclonal antibodies are attached to the end of a pregnancy test stick onto which a woman urinates.

• If she is pregnant, HCG will be present in her urine and will bind to the monoclonal antibodies on the test stick.

• This will cause a change in colour or pattern which will indicate pregnancy.

• These specific monoclonal antibodies in the pregnancy test will only bind with HCG.

How are monoclonal antibodies used to analyse blood

• Monoclonal antibodies are modified so that they will bind to the molecule you are looking for

• They are bound to a fluorescent dye

• If the molecules are in the sample, then the antibodies bind it to it, and the dye can be observed

Advantages of monoclonal antibodies compared to drug and radiotherapy treatments

 

• They only bind to target cells, meaning healthy ones are not affected

What is the effect of exercise and diet on obesity

• Eating more calories than you burn causes you to put on weight

• Eating a large excess of calories, especially if a lot of them come from saturated fat, can lead to obesity

• Obesity can lead to CVD and high blood pressure, as well as type 2 diabetes

• To avoid obesity, eat a diet with less sugar, less processed food, and less saturated fat

 

How to calculate BMI

mass / height²

What is the effect of alcohol on liver diseases

• A high alcohol intake can lead to liver disease

• Fatty liver, common in alcoholics, can lead to liver cancer

• To reduce your chances of liver disease, try and drink less than 14 units of alcohol a week

 

What is the effect of smoking on cardiovascular disease

• Smoking increases the risk of lung cancer, COPD and CVD

• Cigarettes contain over 40 chemicals; they all have different effects - from lung cancer to heart failure

• You should quit smoking if you want to avoid CVD

What are some different treatments for CVD

• Life long medication

• Surgical procedures

• Lifestyle changes

Life long medication as a way to treat CVD

• There are medications to reduce cholesterol or reduce blood pressure

• People with high blood pressure may have to take multiple medications to reduce it

 

Surgical procedures as a way to treat CVD

• Coronary arteries supply the heart with oxygen

• If these are blocked, a coronary artery bypass can be performed

• Another method involves using a metal stent to widen arteries that have been narrowed by plaque

 

Name 3 lifestyle changes as a way to treat CVD

• Reducing salt in diet

  • helps prevent high blood pressure from developing

• Maintaining a healthy BMI (achieved by exercise)

  • reduces strain on the heart

• Reducing the amount of fat you eat

  • reduces the risk of fat deposits in the arteries

Stages of drug development

1. Screening for potential drugs

2. Preclinical trials

3. Clinical trials

4. Approval by a medical agency

What is a blind trial

• Where participants don't know whether they are receiving the new drug or the placebo

• Prevents patient being biased

What is a double blind trial

• Neither the participants nor the doctors know who is receiving the new drug or the placebo

• Prevents bias from doctors

Name the aseptic technique and why it is used - a t p s g m a p d

Autoclave to prepare sterile growth medium and petri dishes

• If this step does not take place, they are likely to be contaminated with other microorganisms

• This can potentially produce a new pathogen

Name the aseptic technique and why it is used - s i l

Sterile inoculating loop

• Kills unwanted microorganisms by passed incoculating loop through a flame

Name the aseptic technique and why it is used - p d s u d

Petri dish storage upside down

• This is to prevent condensation from the lid landing on the agar jelly and disrupting growth

Core practical - investigating the effects of antibiotics on microbial cultures METHOD

• Take a petri dish

• Sterilise it in an autoclave

• Use a permanent marker to draw 3 degments

• Place different antiseptics on filter paper discs, then use forceps to apply the filter paper disc onto to agar plate

• Tape down the lid

• Incubate at 25^o C for 2 days

• Calculate the area of the zones using pi r²

Independent variables for core practical

Different antibiotics or antiseptics

Dependent variable for core practical

Area of the zone of inhibition

Control variables for core practical

• Area of filter paper disc

• Species of bacteria

• Concentration of antiseptic

What are non communicable human diseases caused by

An interaction of a number of factors

Causes of CVD

• High intake of saturated fats

• Inactive lifestyle

Causes of lung and breast cancer

• Smoking for lung cancer

• Age and genetics for breast cancer

Causes of lung and liver disease

• Smoking

• High alcohol intake