nervous system

• Nervous system

  • Type of message: Electrical impulses, neurotransmitters
  • What carries the message: Nerves, synapses
  • Number of target organs: One
  • Speed of reaction: Rapid
  • Duration of effects: Short term
• Reflex arc of touching a hot pan

  1. Stimulus – Hot pan

  2. Heat detected by receptors in the skin

  3. Signal sent along the sensory neuron to the relay neurone

  4. The relay neurone sends a signal to the motor neurone

  5. The motor neurone causes the effector (muscle in the arm) to move the hand away from the hot pan (response)
• stimulus - change in the environment
• effector - muscle or gland that carries out the response.
• 1. sensory neurone
  2. relay neurone (spinal cord in the CNS).
  3. motor neurone (sends the nervous impulse to the effector)
• CNS - central nervous system. includes the brain and the spinal cord.
• PNS - peripheral nervous system. includes all the other parts of the nervous system outside the CNS.
• stimulus --> sensory receptors --> sensory neurons --> relay neurons --> motor neurons --> effector --> response
• Sensory neurone

  A) myelin sheath

  B) nucleus

  C) axon

  D) axon terminal

  E) cell body

  F) dendron

  G) dendrites

  
• Relay neurone (in the CNS)

  A) dendrites

  B) axon

  C) axon terminal

  D) dendron

  E) cell body

  
• Motor neurone (connects to the effector)

  A) nucleus

  B) myelin s

  C) cell body

  D) dendrites

  E) axon

  F) axon terminal

  
• myelin sheath is a fat that coats nerves, to provide insulation and increase the speed of the signal
• dendrites receive the nervous impulse (before cell body)
• axons transmit the nervous impulse (after the cell body)
• reflexes are fast, involuntary responses that happen without conscious thought.
• the eye

  A) suspensory ligament

  B) cornea

  C) iris

  D) pupil

  E) ciliary muscle

  F) lens

  G) optic nerve

  H) retina

  I) sclera

  
• long-sightedness is when the image isn't refracted enough to hit the retina, therefore is focused beyond the retina. it is corrected by a convex lens
• short sightedness is where the image is refracted too much so hits the front of the retina instead of the back. It is corrected with concave lenses.
• accommodation is the ability of the eye to change focus from distant objects to near ones