Lecture 4 vocab

Question 1

What is the speed of thought classically measured by?

Answer 1

Reaction time

Question 2

What speed range from 1 to 270 mph?

Answer 2

Speed of action potential propagation

Question 3

What 3 factors does speed depend on?

Answer 3

Distance, Neuron characteristics, and complexity

Question 4

What are action potentials?

Answer 4

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

Question 5

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

Answer 5

No

Question 6

When do the membrane potentials change?

Answer 6

When ions move in and out of the neurons

Question 7

What defines the phases of the action potential?

Answer 7

K+ and Na+ ion movement

Question 8

What are the stages of action potentials in a neuron?

Answer 8

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

Question 9

What happens in the resting state?

Answer 9

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

Question 10

What happens when neurons start to receive information?

Answer 10

Neurons sum up inputs at the axon hillock

Question 11

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

Answer 11

it opens Na+ voltage channels and depolarize the membrane

Question 12

What happens when the axon hillock depolarizes beyond threshold?

Answer 12

you get an action potential

Question 13

What happens during an action potential?

Answer 13

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

Question 14

What happens in the depolarizing phase?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

What are the two key players in an action potential?

Answer 16

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

Question 17

What do Voltage-gated Na+ channels do

Answer 17

They cause large depolarization and it occurs in the rising phase

Question 18

What do Voltage-gated K+ channels do

Answer 18

They cause repolarization and occur in the falling phase

Question 19

When do Voltage-gated Na+ channels open?

Answer 19

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

Question 20

What happens in the rising phase?

Answer 20

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

Question 21

What determines the amplitude of the rising phase?

Answer 21

The number of open channels

Question 22

What happens in the falling phase?

Answer 22

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

Question 23

What happens during the refractory period(undershoot)?

Answer 23

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

Question 24

What are the two phases of the refractory period?

Answer 24

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

Question 25

What happens in the absolute refractory phase do?

Answer 25

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

Question 26

What happens in the relative refractory phase?

Answer 26

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

Question 27

What happens after the two phases of the refractory period?

Answer 27

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

Question 28

What are sensory neurons?

Answer 28

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

Question 29

How do sensory neurons impact APs?

Answer 29

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

Question 30

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

Answer 30

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

Question 31

Where are APs initiated?

Answer 31

At the axon hillock

Question 32

Where are Voltage-gated Na+ channels concentrated?

Answer 32

At the axon hillock

Question 33

After initiation what can an AP do?

Answer 33

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

Question 34

What do APs do in non-myelinated axons?

Answer 34

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

Question 35

What keeps APs travelling in only one direction?

Answer 35

The refractory period(the undershoot)

Question 36

What do myelinated axons use?

Answer 36

Saltatory conduction

Question 37

What is Saltatory conduciton?

Answer 37

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

Question 38

Where are the voltage-gated Na+ channels clustered?

Answer 38

At the nodes of Ranvier

Question 39

Where do APs only need to be regenerated at?

Answer 39

The Nodes