B1 understanding organisms 2

Malaria
1. caused by a protozoan called plasmodium
  1. feed on human red blood cells
  2. plasmodium is a parasite, humans are host
    1. parasite feed on another living organism causing it harm
2. carried by mosquitoes=vectors,not affected by disease
  1. transmitted to humans by mosquito bites
3. knowledge of mosquito lifestyle has helped stop spread
  1. draining stagnant water
  2. putting oil on top of water surface
  3. spraying insecticide
  4. helped develop new treatments
cancers
1. change in lifestyle and diet can reduce risk of cancer
2. not smoking reduces lung cancer
  1. using sunscreen reduces skin cancer risk
  2. benign tumour cells such as warts divide slowly so are harmless
    1. cancers are malignant tumours, uncontrolled growth and spread
      1. survival and mortality rates should be considered
fight against illness
1. pathogens are disease causing organism
  1. produce the symptoms of an infectious disease by damaging body cells or producing poisonous waste products called toxins
  2. the body protects itself by producing antibodies
    1. lock onto antigens on the surface of pathogens such as bacterium.
      1. kills pathogen
2. human white blood cells
  1. produce antibodies
  2. this results in active immunity
  3. long lasting
  4. vaccination using antibodies from another human or animal result in passive immunity which is a quick but short term affect
  5. each pathogen ha sits own antigens so a specifically antibody is needed for each pathogen
  6. process of immunisation is called vaccination
    1. injects harmless pathogen carrying antigens
      1. antigens trigger a response by whoite blood cells, producing correct antibodies
        memory cells a type of T-lymphocyte cell remai s in body providing long lasting immunity to that disease
        carries small risk but avoids lethal of effect of pathogen
        decreases spread of disease
treatments and trials
1. antibiotics and antiviral drugs are specific in their action
2. antibiotic destroys pathogen
3. antiviral slows down pathogen development
4. new treatments such as vaccinations use animal testing, human tissue and computer models before human trials
  1. a placebo is a harmless pill
    1. used in comparison drug testing
      1. effect of new drug can be assessed
      2. blind trial- patent doesn't know fake/real
        excessive use of antibiotics results in resistant forms of bacteria being more common than non resistant
        reistnat MRSA has thrived causing seriosu ilnness
      3. double blind trial patient or doctor doesn't know
        avoid bias and feel good factor
The eye
1. Learn functions pf eye
  1. binocular vison helps judge distance by comparing images from each eye, the more different they are the nearer the object
    1. the eye can focus light from distant or near objects . this is calle ACCOMADTAION
      1. to focus light on distant objects the ciliary muscles relax and suspensory ligaments tighten so the lens has a less rounded shape
      2. to focus on near object ciliary muscles tighten and suspensory ligamnets slacken so the lens regains a more round shape, a concave lens to correct short sight
    2. red-green colour blindness is caused by lack of specialised cells in the retina
      1. long and short sight is caused by eyeball or lens being the wrong shape . in long sights the eyeball is too short or lens is too thin so image is focused behind the retina, In short sight the eyeball is too long or lens is too rounded so lens refracts light too much so image focused in front of retina
        corneal surgery or glasses or contact lenses correct long nd short sight .
        convex lens corrects long sight. concave lens corrects short sight
Nerve cells
1. they are neurone, nerve impulseles pass along axon
  1. stimulus...receptor...sensory neuron...central nervous sutem...motor neuron...effector....reponse
    1. reflex action
    2. spinal refelex = receptor...sensory neurone...relay neruone...mptor neuron...effector
  2. neurone are adapted to being long,branched endings to pic up impulses and having an insulator sheath
  3. the gap between neurones is a synapse, impulse triggers release of transmitter substance which diffused across the synapse. The transmitter substmace binds with receptor molecules in the membrane of the next neurone causing the impulse to continue.

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B1 understanding organisms 2

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