excitable cells Flashcards

action potential: define the term action potential, list all cell types that are electrically excitable, and define threshold, refractory period, "all or nothing" behavior, depolarisation, repolarisation, hyperpolarisation and saltatory conduction

1
Q

where do action potentials occur

A

excitable cells e.g. muscle cells for contraction or B-cells in pancreas for insulin release

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2
Q

properties of action potentials

A

reliable and rapid

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3
Q

gradation effect on action potential formation

A

if, after synapse, depolarising graded response is sufficient to reach threshold, action potential will occur in that cell; if hyperpolarising graded response also present, causes inhibition

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4
Q

mechanisms responsible for action potential

A

time-course voltage vs time, voltage-gated ion channels and ion movement, permeability changes vs time

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5
Q

what does permeability depend on

A

conformational state of ion channels and population of specific ion channels

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6
Q

how are ion channels opened, inactivated and closed

A

opened by depolarisation, inactivated by sustained depolarisation, closed by hyperpolarisation

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7
Q

where is action potential generated

A

axon

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8
Q

passive propagation

A

decremental; over distance, potential change declines

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9
Q

active propagation

A

non-decremental allows impulses to be conducted down axon due to local current depolarising adjacent area if reaches threshold

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10
Q

nodes of Ranvier

A

larger population of Na+ channels and no myelin; if sufficient depolarisation achieved at next node following local current, action potential generated

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11
Q

saltatory conduction

A

allows rapid velocity of action potential

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