Unit 1 - Topic 4 - Communication and signalling - Section D - Nerve impulse transmission - Part I - Generation of a nerve impulse Flashcards

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1
Q

What is resting membrane potential

A

Resting membrane potential is a state where there is no net flow of ions across the membrane

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2
Q

What does the transmission of a nerve impulse require

A

Changes in the membrane potential of the neuron’s plasma membrane

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3
Q

What is an action potential

A

A wave of electrical excitation along a neuron’s plasma membrane

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4
Q

What do neurotransmitters initiate

A

A response by binding to their receptors at a synapse

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5
Q

What are neurotransmitter receptors

A

Neurotransmitter receptors are ligand-gated ion channels.

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6
Q

What triggers the opening of voltage-gated sodium channels

A

Depolarisation of the plasma membrane as a result of the entry of positive ions triggers the opening of voltage-gated sodium channels, and further depolarisation occurs

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7
Q

What is depolarisation

A

A change in the membrane potential to a less negative value inside

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8
Q

Inactivation of the sodium channels and the
opening of potassium channels restores what

A

The resting membrane potential

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9
Q

What does the binding of a neurotransmitter trigger and what is this followed by

A

Binding of a neurotransmitter triggers the opening of ligand-gated ion channels at a synapse. Ion movement occurs and there is depolarisation of the plasma membrane

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10
Q

What happens if sufficient ion movement occurs, and the membrane is depolarised beyond a threshold value

A

The opening of voltage-gated sodium channels is triggered and sodium ions enter the cell down their electrochemical gradient. This leads to a rapid and large change in the membrane potential.

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11
Q

What happens a short time after the sodium channel opens

A

The sodium channels become inactivated. Voltage-gated potassium channels then open to allow potassium ions to move out of the cell to restore the resting membrane potential

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12
Q

What does depolarisation of a patch membrane cause

A

Neighbouring regions of membrane to depolarise and go through the same cycle, as adjacent voltage-gated sodium channels are opened

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13
Q

What happens when the action potential reaches the end of the neuron

A

It causes vesicles containing neurotransmitter to fuse with the membrane this releases neurotransmitter, which stimulates a response in a connecting cell

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14
Q

Restoration of the resting membrane
potential allows what

A

The inactive voltage-gated sodium channels to return to a conformation that allows them to open again in response to depolarisation of the membrane. Ion concentration gradients are re-established by the sodium-potassium pump, which actively transports excess ions in and out of the cell

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15
Q

Following repolarisation what happens to the sodium and potassium ion concentration gradients

A

Following repolarisation the sodium and potassium ion concentration gradients are reduced. The sodium-potassium pump restores the sodium and potassium ions back to resting potential levels.

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