Lecture 4 vocab Flashcards

1
Q

What is the speed of thought classically measured by?

A

Reaction time

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2
Q

What speed range from 1 to 270 mph?

A

Speed of action potential propagation

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3
Q

What 3 factors does speed depend on?

A

Distance, Neuron characteristics, and complexity

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4
Q

What are action potentials?

A

It uses electricity to convey information very fact. relies on the electrical gradient across the cells membrane, is all or none, and may convey information over long distances

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5
Q

Is there a difference between speed or strength in action potentials?

A

No

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6
Q

When do the membrane potentials change?

A

When ions move in and out of the neurons

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7
Q

What defines the phases of the action potential?

A

K+ and Na+ ion movement

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8
Q

What are the stages of action potentials in a neuron?

A

resting state, depolarizing phase, rising/falling phase, and the refractory period

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9
Q

What happens in the resting state?

A

The leak channels are open(both Na&K but more K leak channels). resting membrane potential is maintained, the net negative charge inside cell is -65mV

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10
Q

What happens when neurons start to receive information?

A

Neurons sum up inputs at the axon hillock

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11
Q

What happens when EPSP(the depolarization unit) are inputted during the resting state?

A

it opens Na+ voltage channels and depolarize the membrane

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12
Q

What happens when the axon hillock depolarizes beyond threshold?

A

you get an action potential

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13
Q

What happens during an action potential?

A

Voltage gated sodium ion channels in the axon hillock open(allowing more sodium into the cell)

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14
Q

What happens in the depolarizing phase?

A

Leak channels open, membrane potential becomes more positive as Na+ enters the cell

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15
Q

At what mV does the action potential have to pass for it to occur?

A

At ~ -40/50mV many more Na+ channels open and an action potential is triggered

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16
Q

What are the two key players in an action potential?

A

Voltage-gated Na+ channels & voltage-gated K+ channels

17
Q

What do Voltage-gated Na+ channels do

A

They cause large depolarization and it occurs in the rising phase

18
Q

What do Voltage-gated K+ channels do

A

They cause repolarization and occur in the falling phase

19
Q

When do Voltage-gated Na+ channels open?

A

They are closed at rest and open in response to depolarization past threshold, letting in Na+

20
Q

What happens in the rising phase?

A

An action potential has been triggered and many Na+ channels open, Na+ channels then become inactive, contributing to undershoot K+ channels are triggered to open, but with a short delay, Membrane potential spikes toward maximum

21
Q

What determines the amplitude of the rising phase?

A

The number of open channels

22
Q

What happens in the falling phase?

A

Na+ channels are inactive, K+ channels open and K+ flows out of the cell membrane, Membrane potential decreases towards resting potential

23
Q

What happens during the refractory period(undershoot)?

A

Na+ channels are inactive and then close, K+ channels remain open, Membrane potential is below resting potential and closer to EK

24
Q

What are the two phases of the refractory period?

A

There is the absolute refractory phase(1st) and the relative refractory phase(2nd)

25
Q

What happens in the absolute refractory phase do?

A

an action potential cannot be triggered (Na+ channels inactive, K+ channels open)

26
Q

What happens in the relative refractory phase?

A

an action potential is possible, but requires a stronger stimulus than at rest (Na+ channels closed, K+ channels open)

27
Q

What happens after the two phases of the refractory period?

A

K + channels close and neuron returns to resting potential through action of ion pumps (return to Phase 1)

28
Q

What are sensory neurons?

A

They are the nerve cells that are activated by sensory input from the environment

29
Q

How do sensory neurons impact APs?

A

The stimulus specific to the neuron activates a specific receptor or ion channel

30
Q

How do APs spread along an axon to reach the axon terminal?

A

Mode of axon potential conduction depends on weather or not the axon is myelinated

31
Q

Where are APs initiated?

A

At the axon hillock

32
Q

Where are Voltage-gated Na+ channels concentrated?

A

At the axon hillock

33
Q

After initiation what can an AP do?

A

It can travel or jump down the axon to the axon terminal

34
Q

What do APs do in non-myelinated axons?

A

They propagate continuously and an influx of sodium in one AP triggers another AP besides the first

35
Q

What keeps APs travelling in only one direction?

A

The refractory period(the undershoot)

36
Q

What do myelinated axons use?

A

Saltatory conduction

37
Q

What is Saltatory conduciton?

A

A faster and more efficient way to propagate an action potential down the axon

38
Q

Where are the voltage-gated Na+ channels clustered?

A

At the nodes of Ranvier

39
Q

Where do APs only need to be regenerated at?

A

The Nodes