Nerves and Hormones

The Nervous System
1. Sense Organs
  1. Detect stimuli
  2. Contain receptors
    1. Groups of cells sensitive to a stimulus
      1. Change stimulus energy in electrical impulses
  3. Eyes
    1. Stimuli=light
    2. Sense=sight
  4. Ears
    1. Sense=hearing
    2. Stimuli=sound
  5. Nose
    1. Sense=smell
    2. Stimuli=Gas Chemical
  6. Tounge
    1. Sense=Taste
    2. Stimuli=Chemical
  7. Skin
    1. Sense=Touch
    2. Stimuli=Pressure, temperature
2. How it works
  1. Sensory Neurone
    1. Carry electrical impulses from receptors to central nervous system
  2. Relay Neurone
    1. Signals from sensory neurone to motor neurone
  3. Motor Neurone
    1. Signals from CNS to effector muscles or glands
  4. Effectors
    1. Muscles contract in response to nervous impulses
    2. Glands secrete hormones
  5. CNS
    1. Made up of Brain and Spinal Chord
Synapses
1. Connection between two neurones
2. Nerve signal transferred by chemicals which diffuse across a gap
  1. These chemicals set off new electrical signal in next neurone
Controlling Fertility
1. Contraceptive Pill
  1. Prevents Pregnancy
  2. Oestrogen stops body from producing FSH
  3. Artificial hormone levels stop if you forget to use it
  4. Pros
    1. Made families smaller-prevents hunger issues
  5. Cons
    1. Destroys eggs
2. IVF
  1. FSH Used
    1. As many eggs as possible mature
  2. Sperm mixed with eggs, fertilised eggs planted in tiny ball of cells
  3. Happens in fallopian tube
  4. Pros
    1. Helps struggling families
  5. Cons
    1. Expensive
    2. Many eggs are killed
  6. Helps fertilisation happen
Plant Hormones
1. Auxins
  1. Controls growth near tips of roots & shoots
  2. Responds to light (phototropism) gravity (gravitropism) and moisture
  3. Moves backwards to stimulate cell elongation
  4. No tip, no auxin
  5. Shoots grow towards light and away from gravity
  6. Roots grow towards gravity and moisture
2. Uses
  1. Selective Weedkillers
    1. Only gets rid of unwanted plants
  2. Fruit Ripening
    1. Helps fruit stay riper for longer-long shelf life
  3. Rooting Powder
    1. Stimulates Growth
  4. Seedless Fruits
Homeostasis
1. Keeping internal conditions stable
2. Ion Content
  1. Lost in sweat
  2. Absorbed into blood
  3. Excess should be removed
    1. Kidneys remove it
      1. Ends up in urine
3. Water Content
  1. Lost in sweat
  2. Lost in breath
  3. Lost in Urine
4. Sugar Content
  1. Food puts glucose into the blood
    1. Normal metabolism of cells removes it
    2. Exercise removes too much
  2. Insulin helps you to maintain correct glucose levels
5. Temperature
  1. Enzymes work best at 37oC
    1. Body tries to maintain this temp
  2. Brain acts as a thermostat
Reflexes
1. Automatic responses to certain stimuli
2. Reduces chances of being injured
3. Stimulus
  1. Receptor
    1. Sensory neurone
      1. Relay Neurone
        Motor Neurone
        Effector
        Response
The Menstrual Cycle
1. Day 1:Bleeding Starts
  1. Day 4-: Lining builds up
    1. Day 14: Egg Released
      1. Day 14-28: Wall Maintained
        Day 28:Lining breaks down
2. Hormones Involved
  1. FSH
    1. Produced by pituitary gland
    2. Causes egg to mature in ovary
    3. Stimulates ovaries to produce oestrogen
  2. Oestrogen
    1. Produced in ovaries
    2. Causes pituitary to produce LH
    3. Inhibits further release of FSH
  3. LH
    1. Produced by pituitary gland
    2. Stimulates release of egg around middle of cycle

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Nerves and Hormones

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	Created by I Turner about 10 years ago