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Bullet point notes |
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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
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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
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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:
¨ 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
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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
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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.
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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.
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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
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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
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SCREENING
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