Bullet point notes
¨ A cancer is caused when a group of cells continue to divide rapidly when they don’t need to.
¨ This is caused by a change to the genes regulating cell division. The changed gene is called an oncogene (a cancer gene)
¨ The mass of additional cells is called a tumour
¨ Tumours have a rapid rate of cell division.
¨ & Abnormal cytoplasmic characteristics.
¨ They are Denser/harder/different colour than the surrounding tissues.
¨ Cells in tumours are clones and remain undifferentiated.
¨ Benign tumours are encapsulated
¨ Malignant tumours easily spread. This is known as metastases
¨ Malignant cells enter bloodstream
¨ Colonise cells in other parts of the body
CARCINOGENS CAUSE CANCER
¨ Removal of tumour surgery
Cancers and screening
¨ Cancers are most successfully treated if detected early
¨ In the UK there are regular screening programmes e.g. Mammography/cervical smears
¨ Programmes to increase awareness of potentially dangerous changes
Reducing Cancer Risk
¨ high fibre/lowfat diet decreases risk of some types of cancer – breast/colon cancers
¨ some high fibre foods contain substances/ß carotene/vitamin A/vitamin C/selenium that may prevent inhibit cancer
¨ Atheroma forms deposits under/in the Epithelium of arteries.
¨ If blood cells are damaged clotting factors are released.
¨ Clots in coronary arteries reduce blood flow to heart muscle therefore reduce O2 supply.
¨ Low saturated fat diets reduce build up of atheroma.
¨ High salt diets cause high blood pressure. As can stress
¨ Lack of exercise leads to:
¨ Atheroma can lead to a loss of elastic tissue which can lead to an aneurysm – this is where a section of the artery collapses forming a balloon full of blood. If this ruptures it can have severe effects
¨ Diets high in saturated fats lead to high plasma levels of LDL’s (cholesterol), this increases the risk of atheroma development
¨ Influenza virus enters body through respiratory surface of lungs. (infects epithelium of nasal passages, pharynx, lungs).
¨ Influenza is spread by droplet infection.
¨ Influenza virus protein coat changes when viral DNA mutates.
¨ Drug treatment difficult because viruses are inside cells therefore drugs cannot reach them. Also the drugs are likely to damage host cell as well.
¨ Retroviruses are RNA viruses
¨ Vaccine= preparation which stimulates lymphocytes to produce antibodies;
¨ Vaccine acts as an antigen / stimulates immune response/ antibody production; to destroy pathogen before it multiplies/ causes disease;
¨ Vaccinations are not effective with 100%of recipients.
¨ Over time immunity may be reduced. This is because the memory cells that are produced in response to the first exposure can die. If this happens a booster is needed as levels of antibody may fall below immune level.
¨ New strains/mutation of pathogen may not be covered.
¨ If a high proportion of a population is vaccinated it will prevent the pathogen spreading to those not vaccinated. This is known as herd immunity.
TYPES OF VACCINE
¨ Killed virulent strain e.g. whooping cough/influenza.
¨ Living attenuated strain e.g. measles/mumps.
¨ Antigens separated from virus e.g. influenza.
¨ Antigen gene transferred to harmless organism e.g. Hepatitis B
¨ Toxoid eg Diptheria – antigen is toxin modify by heat still antigen but not toxic.
¨ Living viruses capable of causing disease in children with weak/slow immune response.
¨ Mutation to virulent form.
¨ Allergic reaction to a component of the vaccine.
¨ Breakdown of alveolar walls
¨ Reduces surface area of alveoli; for diffusion of oxygen/gas exchange
¨ Walls of alveoli broken down to produce larger air spaces
¨ Diffusion of gases/gas exchange reduced/less oxygen enters blood
¨ Narrower bronchioles reduce gas flow
¨ Loss of elasticity reduces gas flow/unable to ventilate efficiently
¨ Lungs permanently inflated
¨ Less energy available/less respiration available for muscles
¨ rate of diffusion into blood insufficient to sustain activity
BRONCHITIS OR EMPHYSEMA
¨ coughing attacks
¨ difficulty in breathing/short shallow breathing
¨ phlegm and coughing blood
¨ inability to sustain any physical exertion
¨ Causes include
¨ (High levels of) air pollution
¨ Industrial smoke/dust etc