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B3 (Nervous system (Damage (Prevents impulses passing, PNS has limited…

- - - - a.k.a. myopia
      - Lens too strong, or eyeball too long
      - Corrected with concave lens to diverge light
    - - a.k.a hypermetropia
      - Lens too weak, or eyeball too short
      - Corrected with convex lens to converge light
    - - Cone cells respond to RGB
      - Missing/altered cone cells result in colour blindness
  - - - Circular muscle contracts
      - Pupil size decreased
    - - Radial muscle contracts
      - Pupil becomes dilated
  - - - Light must converge more
      - Ciliary muscles contract
      - Ligaments relax
      - Lens becomes short and fat
    - - Light must diverge more
      - Ciliary muscle relax
      - Ligaments are tight
      - Lens is pulled long and thin
- - - - Body hairs lower to prevent trapped air
      - Sweat produced, releases heat through evaporation
      - Vasodilation - blood vessels near skin widen, heat loss by radiation
    - - Body hairs rise to trap insulating layer of air
      - Vasoconstriction - reduces blood flow near skin
      - Shivering - increases respiration
  - - - Produced by pancreas
      - Stimulates liver to convert glucose to glycogen
      - When too much glucose
    - - When glucose is gone
      - Converts glycogen back into glucose
    - - Type 1
        
        Cannot make insulin
        
        Normally begins in childhood
        
        Immune system destroys pancreatic cells
        
        Thirst, tiredness, weight loss, thrush
        
        10% of cases
      - Type 2
        
        Cells do not respond to insulin
        
        Late onset, linked to obesity
        
        Progressive - may not be aware
        
        90% of cases
  - - - capsule - outer membrane
      - cortex - outer part
      - medulla - inner part
    - - Glomerular filtrate
        
        Most water
        
        Most salts
        
        Most glucose
        
        Most urea
        
        Passes into Bowman's capsule
      - Remain in blood
        
        Large proteins
        
        Blood cells (too large)
    - - Back into blood
      - Most water (hormone controlled)
      - Most salt
      - All glucose
      - All amino acids
      - Some urea
    - - 1) Hypothalamus detects low water potential
      - 2) Pituitary gland secretes ADH
      - 3) Collecting ducts become more permeable to water
      - 4) More water reabsorbed into blood
      - 5) Low volume, concentrated urine
    - - Hypertonic
        
        High levels of glucose and salts
        
        Drunk before exercise to provide extra energy
      - Isotonic
        
        Equal to blood plasma
        
        Drunk after exercise to replace salt/sugar lost
      - Hypotonic
        
        Low levels of glucose and salts
        
        Thirst quencher, asborbed more quickly
- - - - a.k.a cerebral cortex
      - Personality & conscious thought
      - Sensory information
    - - Fine motor control
      - Posture & balance
    - - Connects hemispheres of cerebrum
    - - Controls body temp.
      - Secretes hormones
    - - Produces hormones
      - Regulates growth, metabolism etc.
    - - Controls visual/auditory systems
    - - Breathing, heart rate, blood pressure
      - Automatic processes e.g. sneezing
  - - - Evidence from stroke victims
      - Electrodes to stimulate regions
      - Computed tomography (CT) scans use X-rays to produce images
      - Magnetic resonance imaging (MRI) uses magnets to identify blood flow
      - fMRI (functional) can do it in real time
    - - Informed consent needed
      - Many case studies needed
      - Difficult to isolate specific regions
      - Sensitive tissue, does not regenerate
- - - - Non-hormonal
      - Barrier method
      - Also prevents STDs
    - - Non-hormonal
      - Release copper which kills sperm
    - - Progesterone & oestrogen
      - Prevents ovulation (inhibits LH)
      - Thickens mcusu from cervix
      - Prevents implantation of fertilised egg
    - - Thickens mucus from cervix
      - Thins lining of uterus (less production of oestrogen)
      - Prevents ovulation (inhibits LH)
  - - - Surgical scarring (F)
      - Issues with cervical mucus (F)
      - Endometriosis - womb lining grows in other places (F)
      - Lack of sperm (M)
      - Hypogonadism - low levels of testosterone (M)
    - - FSH ripens follicle
      - LH causes ovulation
      - hCG used to mature egg
    - - 1) FHS & LH given
      - 2) Eggs harvested and mixed with sperm
      - 3) Embryos placed in womb