Human nervous system -B10

• What is homeostsis ?

  the maintenance of a constant internal environment
• What is negative feedback ?

  a response that opposes the stimulus
• What is the cns?

  brain and the spinal cord
• What is the PNS?

  sensory and motor neurons
• reflexes are:

  • automatic
  • rapid
  • protective
• Explain how a synapse works

  • impulse arrives
  • neurotransmitters released
  • diffuses across synaptic gap
  • binds to receptors on next neuron
  • impulse restarts
• What are the 5 general stages of homeostasis ?

  • stimulus
  • receptor cells
  • coordination centre
  • effector - muscle or gland
  • response
• What glasses are needed for hyperopia?

  Convex lenses
• What glasses are needed for myopia?

  Concave lenses
• How does the eye accommodate for a near object ?

  • ciliary muscles contract
  • suspensory ligaments relax
  • lens becomes rounded
  • greater refraction
• How does the eye accommodate for a far object?

  • ciliary muscles relax
  • suspensory ligaments pulled tight
  • lens flattens
  • less refraction
• What are the stages of a reflex arc?

  • stimulus
  • receptor cell
  • CNS
  • effector
  • response
• What does a sensory neuron do ?

  carries nerve impulse from receptor to the cns
• What does a motor neuron do?

  carries nerve impulse from the CNS to an effector
• What does the hypothalamus control ?

  homeostasis
• what does the cerebellum control?

  movement , muscular activity , balance
• What does the medulla control ?

  unconscious activity eg. heart rate
• What does the pituitary gland control ?

  Hormones
• What does the cerebrum control ?

  Higher brain functions, such as thinking, memory, and voluntary movements.
• Which part of the brain is at the top of the brain ?

  cerebrum

  
• Which part of the eye controls the movement of the lens? Ciliary muscles