Bullet point notes

 

 

CANCER

      A cancer is caused when a group of cells continue to divide rapidly when they dont 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

Cancer

Causes

Lung Cancer             

Chemical carcinogens in tobacco smoke (e.g. tar) and air pollution.

Skin Cancer              

(Melanoma)              

UV light (Damage to ozone layer)

Colon Cancer

Chemical carcinogens e.g. Food additive/named additive

Slow gut transit time

Leukaemia

Ionising radiation

mouth/oesophagus/ larynx cancer

Caffeine/alcohol

 

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/ 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 LDLs

                              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 LDLs (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.

 

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

 

SCREENING

  • Disease detected in early stages so treated quickly

 

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