qs

• Outline the ways in which the structures of a sensory neurone and a motor neurone are similar

  • both have volted gated channels
  • both have axons
  • both have dendrites
  • both have a cell body with a nucleus
  • both have myelin sheath covered with schwann cells
• resting pot of -70mV

  sensory and motor neurones
• transmit nerve impulses from the CNS

  Motor
• connect to other neurones via synapses

  Sensory and motor
• connect to effectors


  Motor
• Why is it described as a transducer

  converts one from of energy into another
• Deformation of plasma membrane at the tip of neurone causes membrane to become more permeable. suggest why

  Neurone channels open cuz of INCREASED PRESSURE
• generation of an AP follows the All or nothing law. Explain that

  If stimulus not strong enough, AP not generated
• Describe how information about strength and intensity of a stimulus is communicated to the brain

  A higher frequency of impulses represents a strong stimulus
• suggest an explanation for the fact that AP's are not generated constantly whilst wearing clothes

  Na+ channels remain open
• Outline role of synapses in nervous system

  • cell signalling
  • convergence - transmit impulses from many neurones to a single neurone
  • Divergence - transmit impulses from a single neurone to many neurones
  • ensure transmission between neurones in one direction only
• Suggest a part of the neurone where the plasma membrane has receptors

  Post synaptic membrane

  explanation: Prevents attatchment of ACHE (neurotrans) to its receptors
• Name the liver cells that can lead to regeneration and the type of cell division that they carry out

  name: Hepatocytes/ Liver stem cells

  division: Mitosis
• Cross section of myelinated neurone (schwann cell structure)

  • cytoplasm
  • axon
  • nucleus
• gap between schwann cels

  nodes of ranvier
• Explain difference in speed of conduction of an AP along length of a myelinated neurone and a non-myelinated neurone

  in Myelinated neurones

  • have a faster conduction rate
  • salt. conduction - AP jumps from node to node
  • depolar. only occurs when Na+ channels are present
  • Longer local circuits
  • Myelinated neurones have longer sections with no Na+ channels present
• Suggest, with reasons, the effects of the toxin once it has entered a neurone

  • vesicles cant fuse with the cell membrane
  • therefore, ACHE not secreted
• Name one hormone that can increase heart rate

  Adrenaline
• Parts of a sensory neurone

  • receptor cell
  • dendrites
  • dendron
  • cell body with a nucleus
  • Axon
  • myelin sheath
  • axon terminal
• Describe and explain how resting potential is establishes and how it is maintained in a sensory neurone

  • Na/K pump uses ATP by Active Transport
  • actively moves Na+ out of neurone and K+ goes in -> Na/K pump actively moves 3 Na+ out of axon and 2 K+ into Axon
  • K+ diffuses freely back out of cell
  • membrane less permeable to Na+ so fewer Na+ diffuse back in
  • volted gated Na+ channels closed
• Comment of relationship between strength of a stimulus and the resulting AP

  Strong stimulus increases but not magnitude of AP