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Effector: Part of the body which responds to stimuli

Central Nervous System

1. Brain
2. Spinal Chord

1. Senesory Neurone: Carries impulses from the receptor to the central nervous system
2. Motor Neurone: Carries impulses from teh central nervous system to the effectors
3. Realy neurone: connects the sensory neurone to the motor neurone.

Motor Neurone

• Myelin Sheath: Is fatty and insulates electricity inside the axon.
• Dendrites: Recieve nerve impulses from sensory cells.

Reflex Action, Involuntary/Voluntary

• Reflex arc is the path taken by an impulse in a reflect arc
• Stimulus->Receptor->Sensory neurone->Relay neurone->Motor Neurone-> Effector->Response

Spinal Chord (Reflex arc only concerned with stimulus from the skin)

• Stimulus (sharp object) -> Sensory neurone (through dorsal route in white matter) -> (synaps in grey matter) -> realy neurone -> (synaps) -> motor neurone (in white matter) -> muscle effector (move hand)
  

The Eye

Know the structure of the eye. Will put image here someday.

How we see

• Light rays from objects are refracted by the cornea and focussed by the lengs. This forms an upside down image on the retina. This upside down image is corrected by our brain so we see the correct way up.

1. ciliary muscles relax
2. suspensory ligaments become tight
3. lends get pulled thin and flat. (less convex)
4. It is the first of the above images

Focussing on near Objects

1. ciliary muscles contract
2. suspensory ligaments relax
3. lens becomes fatter and rounder (more convex)
4. second of above images

Rods and Cones: Contain light sensative pigments which are bleached in light and generate an impulse

 Plant Response

Phototrophic response: growth in response to directional stimulus, light

Top of the plant shoot is the receptor of light for growth

Auxn is a chemical growth regulating substance, which is produced at the tip of shoots when exposed to light.

• Auxin diffuses down the shoot, on the side which is shaded
  • it causes cells in zone of cell elongation to grow faster
  • therefore one side is long/bigger than the other, so the plant bends towards the light.