Health, Disease and the Development of Medicines - Topic 5

Causes:

• Faulty genes can lead to a genetic disorder e.g. sickle cell disease. This can be passed on to offspring, but not any other person.
• Malnutrition e.g. lack of nutrients can lead to a deficiency disease and/or a diet too high in sugars and fats can lead to obesity

Examples of deficiency diseases:

• Kwashiokor
• Scurvy
• Rickets
• Anaemia

BMI = mass (kg) / height (m) x height (m)

Waist:Hip ration = measurement of waist / measurement of hip

• Alcohol is a drug i.e. a chemical substance that alters the away in which your body or mind works
• Alcohol is a depresent i.e. a drug that decreases brain activity and slows down reactions
• Short term effects of drinking alcohol can include loss of balance and co-ordination, blurred vision, poor judgement and alcohol poisoning
• Long term effects are liver disease e.g. cirrhosis, heart disease and stroke, damage to the brain and addictive.

• Cirrhosis occurs when the liver becomes significantly scarred. Scar tissue replaces healthy tissue in the liver and prevents the liver from functioning properly.
• The damage cannot be reversed and eventually can become so extensive that your liver stops functioning

• Too much fat in the diet can increase the risk of many diseases, including Cardiovascular disease.
• This is a general term to decribe diseases associated with the heart and blood vessels.
• One sign of this is high blood pressure which can lead to a heart attack.

• Smoking is the manin contributor to cardiovascular disease. 
• Chemicals from cigarette smoke are absorbed from the lungs into the blood.
• These can lead to:
• Damaged blood vessels
• Increased blood vessels
• Make blood vessels narrower
• Increases the risk of clots forming

High blood pressure:

• Excercise more
• Stop smoking
• Take medication

Atheroma (fatty material that partially blocks a blood vessel)

• Widen the narrowed blood vessel by using stent
• Bypass
• Medication to reduce clotting blood

e.g. HIV virus and Chlamydia bacterium

Spread:

• By contact with sexual fluids during sexual intercourse (reduced by using a condom)
• Passed by pregnant mothers to their unborn baby via the placenta
• People can be screened for STI's.

e.g. HIV virus and Chlamydia bacterium

Spread:

• By contact with sexual fluids during sexual intercourse (reduced by using a condom)
• Passed by pregnant mothers to their unborn baby via the placenta
• People can be screened for STI's.

• All viruses contain genetic material surrounded by a protein coat, or capsid.
• Viruses have to enter a living cell to replicate different viruses and invade different cells e.g. plant cells, bacteria and human cells
• Some types of viruses cause the complete breakdown of a cell - this is called lysis.
• Other viruses can push their way out of a cell through the cell membrane damaging the cell, but not killing it.

• Lytic cycle - when a virus causes lysis.
• Lysogenic pathway - viral genetic material is inserted into the cells. Every time the cell divides the virus' genetic material is replicated as well. At a later stage viral protein is made and the virus returns to the lytic pathway

• The effect of viruses on bacteria can be studied using a bacterial lawn plate.
• These are petri dishes containing nutrient agar covered with a thin layer of bacteria
• Viruses are added. 
• Clear patches occur where the bacteria have been killed
• The larger the clear area the more effective the viruses are at replicating and killing bacteria.
• The radius is the circles can be used to calculate the size of the clear area. (pi x r squared)

• Viruses cannot replicate outside a host cell
• Virus attaches to host cell and enters
• Takes over cell processes for making: copies of viral DNA and viral proteins via protein synthesis
• Components assemble to form many new viruses
• These escape from the cell, destroying it i.e. lysis occurs
• Viruses infect other cells

• Plants are also attacked by pathogens e.g. bacteria, viruses and fungi
• They defend themselves by using: physical and chemical barriers
• Waxy cuticles on plants act as a physical barrier
• Bark will protect woody plants
• Pathogens also have strategies to penetrate cells e.g. fungal pathogens releasing enzymes to help them get nutrients inside plant cells
• They enter via softer tissues in young shoots

• Physical barriers do not protect the plants from herbivores, inclusing pests like caterpillars (leaf eating) and aphids (sap-sucking).
• Aphids penetrate the phloem tissue and can transfer viruses into the plant
• Many plants use chemical defences like poisons or insect repellents
• Producing chemicals uses energy so it must be worth the cost for the plant 
• E.g. produce poisons all the time e.g. foxglove
• Only produce chemicals when attacked

• Plants show signs of stress when conditions are not favourable for growth. Farmers need to identify causes of stress to be able to treat crops and prevent loss of yield. e.g:
• Too much or too little water
• Lack of soil minerals
• Attack by pests and disease

• Observe visible symptoms e.g.
• Changes in colour and growth
• Spots on leaves
• Lesions on stems
• Distrubution analysis i.e. looks at where the damaged plants occur within a field. Drones can be used to take photos and patterns compared e.g. wind could spread fungal spores in a particular direction; soil pathogens are passed to adjacent plants

• Identifying genetic material
• Grow pathogens from diseased plants on nutrient agar
• Use a microscope to study and identify pathogens
• Test soil samples for nutrients and toxins

• Mnay medicines have been developed from substances plants use to protect themselves e.g. Aspirin (produced from salicylic acid made by willow trees) and Artemisinin (extracted from the wormwood plant)
• Most modern medicines are now produced in a lab using chemical substances. 
• They are tested in bacterial cultures or human cells
• Aseptic techniques are required to prevent contamination e.g. autoclave to sterilise equipment and growth medium (nutrient agar)

SEE PHYSICAL BARRIERS TABLE IN BIO FOLDER TOPIC 5

• All the organs in the body that protect against disease
• Attacks pathogens and tries to prevent them causing harm
• Uses antigens to identify if something belongs to the body or comes from outside
• Antigen = A protein on the surface of all cells and viruses
• Lymphocytes:
• White blood cells
• Have proteins on their surface called antibodies
• Antibodies attach to a specific antigen on a microorgansim and helps to destroy or neutralise it. 

• Pathogens have antigens on their surface that are unique to them
• A lymphocyte with an antibody that perfectly fits the antigen is activated
• This lymphocyte divides over and over again to produce clones of identical lymphocytes
• Some of the lymphocytes secrete large amounts of antibodies. The antibodies stick to the antigens and destroy the pathogen
• Other lymphocytes remain in the blood as memory lymphocytes, ready to respond immediately if the same antigen ever enters again.

• A lymphocyte that remains in the blood for a long time after an infection or vaccination
• Cause a faster secondary response if the same pathogen attacks again to prevent you from becoming ill
• i.e. you are immune to that pathogen
• Immunity to one pathogen does not make you a immune to a different pathogen - different pathogens need different antibodies to attack them.

• Making someone immune to a pathogen artificially e.g. by vaccinating them.
• The vaccine contains weakened or inactive pathogens, or bits of the pathogen that include the antigens
• Vaccines may be injected or taken by mouth
• Herd immunity = when the majority of people in a group are immunised which provides protection to the few who are not by reducing their chanced of meeting an infected person.

• Antibiotics are substances that either kill or inhibit their growth or reproduction.
• Antiobiotics do not harm human cells, they therefore can be used to attack bacterial infections that the immune system cannot control
• Different antibiotics work in different ways. e.g. ceftazidime works by damaging the cell walls of certain bacteria; penicillin prevents the formation of a cell wall
• Many bacteria are developing resistance to antibiotics and new antibiotics must be developed to control infection.

1. Pre-clinical stage - tested on cells or tissues in the lab. Can the drug eneter the cells and have the desired effect?

2. Tested on animals to see how it works on a whole body, without risk to humans

3. Small clinical trial - tested on a small group of healthy people to check for side effects (unitended, often unpleasant or harmful, effect of a medicine)

4. Large clinical trial - tested on many people with the disease. The correct dose is determined.

5. Prescribed by doctors if all tests are passed

• Monoclonal antibodies can be made to match the antigens on pathogens i.e. they can be used to identify pathogens.
• They can be made to stick to platelets (fragments of blood cells that help the blood to clot)
• If a cloit forms in the wrong place it can cause a heart attack or a stroke (clot in the brain)
• They can be used to diagnose cancer by detecting cancer cells. Radioactive antibodies attach to cancer cells and can be detected using a PET scanner.
• Cancer cells can be killed using drugs (chemotherapy) or ionising radiation (radiotherapy)

• These treatments also damage healthy cells
• Cancer drugs can be attached to monoclonal antibodies so that they are delivered to cancer cells only.
• This reduces the amount of drug needed to kill cancer cells and reduces the risk of damaging healthy cells.

• Monoclonal antibodies = many identical antibodies

Uses:

• Pregnancy tests
• To identify pathogens
• Identify clots in the brain or heart
• Medical diagnosis e.g. detect cancer cells
• Used in chemotherapy to target cancer cells

• A lymphocyte that produces the required antibody is fused with a cancer cell to form hybridoma cells
• Stage 1 - a particular antigen is injected into a mouse. The mouse produces lymphocytes that make antibodies against the antigen
• Stage 2 - the lymphocutes are fused with cancer cells grown on culture medium in the lab to form hybridoma cells
• Stage 3 - the hybridoma cells divide and make monoclonal antibodies against the antigen

• Pregnancy test sticks contain monoclonal antibodies that react to a hormone in the urine that is produced after fertilisation has occured. 
• The hormone (antigen) matches the antibodies
• A dye turns from colourless to red to confirm pregnancy
• Site A - line containing monoclonal antibodies. Line will appear when the test is positive.
• Site B - line contains antibodies to a protein that is always present in urine and when it appears, it shows that the test is working properly.

• Risk factors are things that are linked to an increase in the likelihood that a person will develop a certain disease during their lifetime.
• They don't gaurantee that someone will get the disease

• Non-communicable diseases can have knock-on effects for local areas.
• For example, in areas where there are high levels of obesity, smoking or excess alcohol consumption, there's likely to be a high occurence of certain non-communicable diseases, e.g. cardiovascular or liver disease.
• This can put pressure on the resources