health, disease and developing medicine

• what is health

  'a stare of complete physical, mental and social wellbeing' - World Health Organisation
• what is infirmity

  weakness of frailness, commonly due to old age
• what is disease

  a condition where part of the organism doesnt function properly
• what is a communicable disease

  a disease caused by pathogens

  can be spread between individuals
• what is a non-communicable disease

  a disease which cannot be transmitted between individuals
• what happens if you are affected by a disease

  you are more susceptible to other diseases (more likely to catch another disease)
• cholera

  caused by bacteria (vibrio cholerae)

  symptoms = diarrhoea

  spread through contaminated water

  prevent by having access to clean water supply

  communicable disease
• tubercolosis

  caused by bacteria (myobacterium tubercolosis)

  symptoms = coughing, lung damage

  spread through air when infected person coughs

  prevent by well ventilated homes, good hygiene, affected avoid public

  communicable disease
• malaria

  caused by protists (mosquitos)

  symptoms = damage to red blood cells, maybe liver

  spread through mosquitos (vectors-pass to humans but dont get infected)

  prevent by having mosquito nets, insect repellant

  communicable disease
• stomach ulcers

  caused by bacteria (helicobacter pylori)

  symtoms = stomach pain, vomiting, nausea

  spread through oral transmission(swallow contaminated food/water)

  prevent b having good hygiene, clean water

  communicable disease
• ebola

  virus

  symptoms = haemorrhagic fever (fever with bleeding)

  spread through bodily fluids

  prevent by isolating infected, sterilising areas

  communicable disease
• chalara ash dieback

  fungus which infects ash trees

  symptoms = leaf loss, bark lesions/wounds

  spread through air, wind

  prevent by removing infected trees, restrict movement of ash trees

  communicable disease
• what is a virus

  a protein coat around genetic material (not a cell)

  infect living (host) cells to reproduce

  life cycle starts when it infects a new host
• lytic pathway

  1. virus attaches to specific host cell, injects genetic material
  2. virus replicates genetic material which produces components of new viruses
  3. the host cell bursts and releases new viruses which infect more host cells
• lysogenic pathway

  1. injected genetic material is incorporated with host cell's dna
  2. the host cell divides, and the infected genetic material is replicated each time (virus = inactive)
  3. a trigger (presence of a chemical) causes viral genetic material to leave genome (dna)
  4. enters lytic pathway
• chlamydia

  bacteria which can only reproduce inside a host cell

  not always symptoms

  can cause infertility

  prevent by wearing condoms, screening individuals, avoiding sexual/genital contact
• HIV (human immunodeficiency virus)


  kills white blood cells, eventually leads to AIDS

  the immune system deteriorates, fails and is vulnerable to other infections

  spread by bodily fluids

  prevent by wearing condoms, avoid sharing needles, medication to avoid passing from mother to baby, screening, proper treatment
• physical plan defences

  waxy cuticle stops pathogen/pests entering/damaging, stops water collecting on leaf

  cell wall made from cellulose stops things entering cell
• chemical plant defences

  antiseptics to kill bacteria and pests

  produce chemicas to deter pests
• chemicals from plants which treat/relieve human symptoms

  quinine from bark of cinchona tree treated malaria

  chemical from bark and leaves of willow tree made aspirin which relieved pain and fever
• plant diseases in the field

  observations such as abnormal growth, colour

  environmental causes such as nutrient deficiency

  patches = spread through soil

  random distribution = airborne
• plant diseases in the lab

  very accurate

  detect antigens by using monoclonal antibodies and therefore detect the pathogen the antigen has come from

  detect dna by collecting small amounts of plant dna which contins pathogens
• physical human defences

  skin which is a barrier to pathogens. blood clots also seal wound if damaged

  hair/mucus in nose which traps particles

  trachea/bronchi cells which contains mucus which traps pathogens and is wafted by cilia to back of the throat to be swallowed
• chemical human defences

  hydrochloric acid in stomach kills most pathogens

  lysozymes in tears which kills bacteria on surface of the eye
• immune system

  white blood cells destroy pathogens

  b-lympocyte = type of white blood cell

  1. pathogen has antigens
  2. lymphocytes have antibodies which bind onto antigen of pathogen
  3. found and destroyed by other white blood cells
• primary immune response

  when a pathogen enters the body the first time, the immune response is slow because there arent enough lymphocytes to make the antibody. the body slowly makes antibodies, and whilst doing so, the infected person starts to show symptoms. the body eventually makes enough antibodies to get rid of the pathogen
• secondary immune response

  whilst making the antibodies, memory lymphocytes are also produced which remember a specific antigen for a long time. this means that if the same pathogen enters the body again, the (secondary) immune response would be faster and stronger as there are already enough antibodies to get rid of the pathogen. as this happens very fast, the pathogen is gone before the person starts to show symptoms
• immunisation

  when dead/inactive pathogens are injected into the body which carry antigens. the body makes antibodies and memory lymphocytes

  if a live pathogen enters the body, the secondary immune response is fast as there are already memory lymphocytes

  some diseases have been virtually wiped out due to immunisation (smallpox)

  however this doesnt always work and might have a bad reaction to the vaccine
• herd immunity

  when most of the population are immunised so it is harder for the disease to spread

  helps protect those who cannot get the vaccine or those that dont have it as there are less people to pass on the disease
• monoclonal antibodies

  lots of clones of a single B-lymphocyte

  all antibodies are identical, all target one specific protein antigen

  can bind to anything
• producing monoclonal antibodies

  • antibodies are produced by lymphocytes which dont divide easily
  • tumour cells divide lots, but dont produce antibodies
  • fusing a mouse B-lymphocyte and myeloma (tumour) cell creates hybridoma cell
  • hybridoma cells can be cloned to get identical cells, and divide quickly to produce same (monoclonal) antibodies which can be collected and purified
• monoclonal antibodies and pregnancy tests

  pregnant women have hormone HCG which is found in urine

  1. bit you urinate on has antibodies to hormone and blue beads
  2. the test strip (which turns blue if pregnant) has more antibodies to hormone stuck to it so they dont move
  3. if youre pregnant, hormone binds to antibodies on the blue beads, the urine moves up the stick carrying the hormone and the beads which eventually bind to antibodies on the strip. blue beads get stuck on the strip and turn it blue

  if not pregnant, the blue beads have no hormone to stick to, so test strip doesnt turn blue
• monoclonal antibodies can target cancer cells

  cancer cells have proteins on cell membranes (tumour markers) which arent found on normal body cells

  in a lab, monoclonal antibodies can be made to bind to tumour markers, which helps diagnose and treat cancer
• monoclonal antibodies help diagnose cancer

  1. antibodies are labelled with a radioactive element which is given to a patient through a drip (goes into blood and carried around body)
  2. when the antibodies come into contact with cancer cells, they bind to the tumour markers
  3. a picture of the patient's body is taken with a special camera which detects radioactivity. where there's a bright spot, there are cancer cells. this helps see where the cancer is, the size and to see if its spreading
• monoclonal antibodies helps target drugs to cancer cells

  1. an anti-cancer drug is attached to monoclonal antibodies
  2. they are given to a patient through a drip
  3. the antibodies only target specific cancer cells as they only bind to the tumour markers
  4. the drug kills the cancer but no other normal body cells near the tumour
  5. this has lower side effects compared to other drugs or radiotherapy as they can kill normal cells too
• monoclonal antibodies to find blood clots

  1. when blood clots, proteins in blood join together to form a solid mesh
  2. monoclonal antibodies bind to these proteins
  3. a radioactive element can be attached to the antibodies, so when injected into the body, a radioactive camera shows bright spots which is where the blood clot is

  this is useful as it finds potentially harmful blood clots and so they can be removed before they harm the patient
• antibiotics

  work by inhibiting processes in bacterial cell but not the host cell (inhibit building of cell wall which prevents bacteria dividing so kills them-human host cells dont have cell wall)

  there are different antibiotics for different types of bacteria

  dont destroy viruses
• testing for drugs

  1. create drug
  2. test on human cells and tissue in lab (pre-clinical testing)
  3. test on live animals (pre-clinical testing)
  4. test on healthy volunteers (clinical testing)
  5. test on people suffering with illness (clinical testing)
  6. approved by medical agency
• pre-clinical testing

  tested on human cells and tissue in lab

  tested on live animals to see if it produces effect you need, found our best dosage and to see if it is toxic
• clinical testing

  test on healthy volunteers to see if theres any harmful side effects on humans

  tested on people suffering to find optimum dosage