nervous coordination Flashcards

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1
Q

describe how an action potential is maintained across the axon membrane in a neurone (3)

A
  • Higher concentration of sodium ions outside the neurone and higher concentration of potassium ions inside the neurone
  • membrane is more permeable to potassium ions
  • 3Na+ actively transported out and 2K+ actively transported into the membrane
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2
Q

why is speed of transmission faster along a myelinated axon then along a non-myelinated axon (3)

A
  • myelination provides electrical insulation
  • in a myelinated neurone depolarisation occurs at the nodes of ranvier
  • in a non-myelinated neurone depolarisation occurs along the whole length of the axon
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3
Q

describe the events involved in transmission along a cholinergic synapse (6)

A
  • depolarisation (nerve impulse) of the presynaptic membrane
  • calcium ion channels open and calcium ions enter the synaptic knob
  • calcium ions cause the synaptic vesicles to fuse with the pre-synaptic membrane and release acetylcholine (neurotransmitters)
  • acetylcholine diffuses across the synaptic cleft
  • acetylcholine attaches to receptors on the post-synaptic membrane
  • sodium ions enter the post synaptic neurone leading to depolarisation
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4
Q

explain the role of inhibitory substances (GABA) (6)

A
  • GABA receptors found on the post-synaptic membrane
  • GABA binds to its receptors increasing membrane permeability to Cl- ions
    -Cl- ions diffuse through Cl- ion channels
  • causes inside of post-synaptic neurone to become more negative
  • more Na+ ions required to reach threshold for action potential
  • so less likely to generate an action potential when stimulated
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