Bullet point notes

CANCER

¨      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

Treatment

¨      Removal of tumour surgery

¨      radiotherapy

¨      chemotherapy

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

CARDIOVASCULAR DISEASE

¨      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:

¨                              low BMR (basal metabolic rate)

¨                              raised resting pulse

¨                              excess LDL’s

¨                              poor circulation in the heart muscle.

¨      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

VIRAL DISEASES

¨      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

VACCINATION

¨      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.

DANGERS

¨      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.

MENSTRUAL CYCLE

¨      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

FSH

¨      stimulates growth / development of follicle;

¨      stimulates secretion of oestrogen;

¨      enhances effect of LH in stimulating ovulation;

LH

¨      stimulates (final) development of follicle;

¨      stimulates ovulation;

¨      stimulates development of corpus luteum;

¨      stimulates production of progesterone / corpus luteum produces progesterone.

Oestrogen

¨      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:

Progesterone

¨      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;

DEMOGRAPHICS

• During the high stationary stage the population has a high fluctuating death rate and birth rate. The diseases are mainly infectious diseases e.g. cholera. Many such diseases are waterborne. These usually affect children most causing a high infant mortality. There is an absence of medical facilities. There is an uncertain food supply.

• In the early expanding stage (Agricultural revolution meant) more food was available/better diet. There was also better sanitation/water supply.

• In the late expanding stage children ceased to be economically useful/child labour laws passed/education compulsory. This made the desired family size smaller (especially when infant mortality decreased).

• In the low variable stage there is improved contraception and women’s aspirations depend on lower family size

AGING

¨      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

EMPHYSEMA

¨      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

¨      Smoking

¨      Industrial smoke/dust etc

BEHAVIOUR

¨      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;

territories

¨      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

Aggressive encounters

¨      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

Kinesis

¨      Move faster in unfavourable environment

¨      increases chance of finding suitable environment/remaining in a favourable environment

¨      Rate of movement related to intensity of stimulus

Habituation

¨      Stimulus repeated many times;

¨      No reinforcement by actual predator;

¨      Nerve adaptation/ nerve impulses blocked

GROWTH

¨      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.

SCREENING

• Disease detected in early stages so treated quickly