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.
¨ oestrogen stimulates LH production
¨ LH produced by pituitary gland
¨ LH stimulates ovulation
¨ LH stimulates formation of corpus luteum
¨ LH stimulates production of progesterone (by corpus luteum)
¨ progesterone maintains / thickens uterine lining
¨ LH inhibits FSH production
¨ without ovulation there is no egg release / no egg to fertilise
¨ stimulates growth / development of follicle;
¨ stimulates secretion of oestrogen;
¨ enhances effect of LH in stimulating ovulation;
¨ stimulates (final) development of follicle;
¨ stimulates ovulation;
¨ stimulates development of corpus luteum;
¨ stimulates production of progesterone / corpus luteum produces progesterone.
¨ stimulates repair / proliferation of uterine lining;
¨ (as it rises in concentration) it inhibits FSH;
¨ eventually positive feedback on FSH;
¨ (as it peaks its concentration) it stimulates release of LH:
¨ maintains / proliferates the uterine lining;
¨ inhibits release of FSH;
¨ inhibits release of LH;
¨ fall in progesterone results in menstruation;
¨ fall in progesterone removes inhibition of FSH and new cycle commences;
¨ Osteoporosis /loss of calcium from bones/ rate of cell replacement decreases/ less protein made as DNA becomes defective;
¨ fall in metabolic rate/decreased activity;
¨ loss of brain cells causes slower responses, slower learning ability, loss of memory;
¨ lower rate of nervous conduction reduces reaction time;
¨ cartilage on joints wears own/arthritis reduction in ease of movement;
¨ arteriosclerosis/atherosclerosis reduce efficiency of circulatory system
¨ reduced vital capacity of lungs/ reduced elasticity become more breathless on exertion;
¨ Faulty copying of DNA and a lifetime of exposure to mutagens leads to accumulated genetic changes/mutations. So faulty proteins may be made
¨ cross-linking of proteins such as collagen in connective tissue, causes connective tissue to stiffen e.g. in heart, affecting resting cardiac output;
¨ other effect, e.g. wrinkling of skin/ reduced renal filtration rate/ slower circulation of blood.
¨ Body’s immune system produces antibodies against its own cells as the immune system deteriorates with age. Which also allows abnormal cells to proliferate
¨ 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
¨ Inborn response/not learned/genetically determined; e.g. ability to produce a song of a specific length and containing specific notes
¨ shown by all individuals of species
Benefits of courtship behaviour:
¨ Species recognition;
¨ sex identification;
¨ courtship/attract a mate;
¨ synchronise sex behaviour/strengthen pair bond;
¨ territory marking/defence;
¨ In winter maintains food supply to survive adverse conditions
¨ used for acquiring a mate/pair formation/courtship
¨ retaining the mate/pair bonding
¨ food supply for young/less competition for food
¨ protection of young
¨ less disease transmission
¨ lower chance of predation
¨ natural selection of fittest/only fittest obtain territories
¨ Less chance of injury
¨ requires less energy
¨ is established territories intruder is submissive/withdraws (so fighting is not needed)
¨ fighting used when both individuals have a chance of acquiring it
¨ song/display used to advertise fitness
¨ Move faster in unfavourable environment
¨ increases chance of finding suitable environment/remaining in a favourable environment
¨ Rate of movement related to intensity of stimulus
¨ Stimulus repeated many times;
¨ No reinforcement by actual predator;
¨ Nerve adaptation/ nerve impulses blocked
¨ Growth of brain and head very rapid in early years
¨ Enables scope for greater learning in childhood;
¨ allows development of complex types of behaviour;
¨ extended childhood allows longer period of learning;
¨ No need for reproductive organs to develop until adulthood;
¨ Reproductive organs develop slowly until puberty (12/13 years), when development is faster;
¨ Growth of reproductive organs at puberty allows reproductively mature individuals to be distinguishable;
¨ Reproductive organs are developing when the body/ person is mature enough to rear children
¨ delays reproduction until physical/ mental maturity reached.