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B5 Test Revision (The Nervous System (Nerves and Neurones (A nerve is a…

- - - - Coughing
        
        Object about to go down windpipe
        
        Diaphragm relaxes to exhale air
      - Sneezing
        
        Foreign object in nose
        
        Sneeze to push out object
      - Blinking
        
        Object comes towards eye
        
        Close eye
      - Knee jerk
        
        Tendon under knee cap stretched
        
        Leg extends
    - - Reflexes happen in the following sequence
        
        Stimulus
        
        Recpetor
        
        Sensory neurone
        
        Relay neurone
        
        Motor neurone
        
        1 more item...
  - - - Electrical signal travels down the first neurone to the nerve ending
        
        Signal cannot cross the gap and so is converted to a chemical transmitter, this diffuses across the gap and binds to a receptor on another neurone
        
        The binding causes a new electrical signal to be produced and the neuro-transmitter is destroyed
- - - - Nerve impulses sent to skin
        
        In the skin...
        
        Hair lies flat
        
        Body temperature falls back to normal
        
        Vasodilation
        
        Sweat glands produce sweat, takes heat from skin as it evaporates
  - - - Nerve impulses sent to skin
        
        In the skin...
        
        Hair stands on end to trap an extra layer of heat
        
        Body temperature rises back to normal
        
        Vasoconstriction
        
        In the muscles...
        
        Shivering to produce heat energy through respiration
- - - - Short and fat (near objects)
        
        Long and thin (far objects)
    - - Slack (loose) for near objects
        
        Taught (tight) for far objects
    - - Contracted to be shorter (near object)
        
        Relaxed to be longer (far objects)
    - - A lot (near objects)
        
        A little (far objects)
    - - Spreading out for a near object
        
        Near parallel for far objects
  - - - Causes include: eyeball too long, cornea too curved or lens is too strong
        
        Concave lens helps to focus light on back of retina
      - Light rays focus before/ in front of the retina
    - - Causes include: eyeball too short, cornea not curved enough, lens isn't strong enough, ciliary muscles not strong enough
        
        Convex lens helps light focus on back of retina
      - Light rays focus behind retina
- - - - They're produced in parts of the body called endocrine glands
  - - - Produces thyroxine
        
        Controls metabolic rate
    - - Produces adrenaline
        
        Prepares body for 'fight' or 'flight'
    - - Produces many hormones
        
        Controls the thyroid, ovaries and testes
      - Also known as the master gland as it produces hormones which act upon other organs/glands (stimulating production of other hormones)
      - Acts in response to body conditions and releases hormones to stimulate other glands to produce particular effects
    - - Produces insulin
        
        Controls blood sugar
    - - Produces oestrogen and progesterone
        
        Controls menstrual cycle
    - - Produces testosterone
        
        Controls puberty in males and sperm production
- - - - Sweat - water ions and urea lost - unconrolled
    - - Produces urine loses water - excess water, ions and urea removed via kidneys - controlled
    - - Breathing out water vapour (exhalation) - uncontrolled
    - - Incomplete re-absorption of water
  - - - Skin through sweating
      - Passing urine produced by kidneys
  - - - Advantages
        
        Long term cheaper
        
        Lead a normal life
      - Disadvantages
        
        Surgery carries a huge risk
        
        Kidney could be rejected so you're on immuno-suppresant drugs
        
        Precise tissue match is needed
        
        Shortage of donors
    - - Disadvantages
        
        Long term very expensive
        
        Must be connected to machine for several hours each week
        
        Strict diet
        
        Only works for limited time
      - Advantages
        
        Keeps you alive
        
        Enables very ill patients who wouldn't survive an op to live
        
        Short term cheaper
- - - - Sugar used to make energy in respiration, found in blood plasma
    - - Substance made of glucose, stored in liver
    - - Hormone, tells body to change glucose to glycogen
    - - Hormone that changes glycogen back to glucose
  - - - Little or no insulin in the pancreas, blood glucose levels rise as it cannot enter the cells
      - Mainly in the under 40s of the population
    - - Slow rise of blood sugar levels as not enough glucose gets in the cells, this gets higher and higher until pancreas wears out
      - Mainly in the over 40s of the population
    - - Blurred vision
      - Tiredness
      - Slow healing
      - Thirst
      - Common urination
      - Weight loss
- - - - Stimulates shoot elongation, seed germination, fruit and slower maturation - assures seeds to germinate at the right time of year, promotes flowering in correct day length. (Regulates growth)
    - - Responsible for ripening of plants/fruits and can be used to speed up ripening
        
        Unusual as it's a gas, produced by ageing part of plants, stimulates enzymes which ripen fruit - can also control cell division
    - - Increase shoot growth, inhibits root growth
- - - - Receives impulses from other parts of brain and spine, coordinates movement and posture
    - - Controls a lot of unconscious activities such as heart rate and breathing rate
    - - The largest part of the human brain, made up of 2 halves. Contains sensory centre, motor centre, speech, language, memory, consciousness and intelligence
- - - - Stimulates ovaries to make oestrogen
      - Causes eggs in ovaries to mature, one each month
    - - Prevents more FSH being secreted, repairs uterus lining after menstruation