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PHAR1803 > Action Potentials > Flashcards

Action Potentials Flashcards

1
Q

How many signals can a neuron send at once?

A

1

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2
Q

A neuron can only transmit at a uniform…

A

-Strength
-Speed

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3
Q

What can a neuron vary?

A

The frequency of the signals

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4
Q

What is voltage?

A

Measure of potential energy generated from separated charges

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5
Q

What is another word for voltage?

A

Membrane potential

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6
Q

What is another word for membrane potential?

A

Voltage

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7
Q

What is current?

A

Flow of charge from one point to another

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8
Q

What is the equation for current?

A

Current = Voltage/Resistance

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9
Q

What is resistance?

A

Whatever is getting in the way of the current

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10
Q

Where is a resting neuron more negative?

Inside or Outside

A

On the inside

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11
Q

Where is a resting neuron more positive?

Inside or Outside

A

On the outside

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12
Q

What is the resting membrane potential?

A

-70mV
Polarised

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13
Q

What is the net movement of ions through the sodium-potassium pump?

A

2K+ in and 3Na+ out

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14
Q

What maintains resting membrane potential?

A

The sodium-potassium pump

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15
Q

What does the sodium-potassium pump help achieve?

A

Makes it more positive on the outside

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16
Q

What is another word for the difference in membrane potentials?

A

Electrochemical gradient

17
Q

What are voltage-gated channels?

A

They open and close in response to changes in membrane potential

18
Q

At what voltage do Na⁺ voltage-gated channels open?

A

55mV

19
Q

What are ligand-gated channels?

A

They open when neurotransmitters latch to their receptors

20
Q

What is an example of a ligand-gated channel?

A

Seratonin

21
Q

What are mechanically-gated channels?

A

-They open in response to physical stretching of the membrane
-Ions quickly diffuse down concentration gradient

22
Q

What is the propagation of an action potential?

A

Action potentials spreading over the surface of an axon membrane

23
Q

How is an action potential propagated over the surface of the axon?

A

-As Na⁺ flows into the cell during depolarisation, the voltage of adjacent areas is affected and their voltage-gated Na⁺ channels open
-Self-propagating along membrane

24
Q

What is another phrase for a travelling action potential?

A

Nerve impulse

25
Q

What is another name for a nerve impulse?

A

Travelling Action Potential

26
Q

What is continuous conduction?

A

-Unmyelinated fibres
-Step-by-step depolarisation of each portion of the length of the axolemma

27
Q

Where does repolarisation occur?

A

Nodes of Ranvier

28
Q

Why can repolarisation only occur at nodes of ranvier?

A

There is a high density of voltage-gated ion channels

29
Q

What is saltatory conduction?

A

Current carried by ions flows through extracellular fluid from node to node

30
Q

Where does saltatory conduction take place?

A

Myelinated axons

PHAR1803 (27 decks)

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