Chapter 3 pt 2 Flashcards

Exam 1

1
Q

What is happening at resting membrane potential?

A
  • During the resting potential there is free-flowing “leaky” K+ channels and closed Na+ channels
  • When a depolarizing stimulus comes along, the membrane potential becomes less negative and approaches the threshold potential (-40mV)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens when the membrane potential reaches threshold?

A
  • The voltage-gated Na+ channels open, triggered by the certain membrane voltage being reached (not by a chemical)
  • the channels activate: Na+ ions rush into the cell
  • the membrane potential moves towards the positive range
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is going on when the voltage-gated Na+ channels inactivate?

A
  • After a fixed period of time after the positive voltage is reached, the Na+ channels inactivate
  • Relative refractory period: step 4… the neuron can fire an action potential but needs a stronger stimuli

inactivation= state in which channel is “closed”/ nonfunctioning and temporarily unable to open again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Voltage-gated K+ channels activate

A
  • As the inside of the cell becomes more +, voltage-gated K+ channels open.
  • K+ moves out and the resting potential is restored. MORE flows out bc of delayed activating channels opening
  • The membrane becomes more negative again
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is up w the leaky K+ channels throughout the action potential process?

A
  • The leaky K+ channels remain open throughout the whold process- what changes is the direction the K+ is flowing
  • Movement is in both directions until the action potential peak occurs, at this point it is only allowed to go outside.
  • Mostly driven by the concentration gradient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is active propagation?

A
  • Active propagation of an action potential is slow (10m/s) but it does not weaken due to sodium-ion channels “recharging”
  • Takes many small steps down the axon with some chance of failure at every step due to not enough Na+ ions… requires activation of valtage-gated sodium channels along the entire length of the axon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is passive propagation?

A
  • Not dependent on voltage changes
  • Is fast but it weakens so it could disappear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Saltatory Conduction

A
  • An action potential starts at the axon hillock, moving passively through the myelinated segment- quick but weakening
  • When it reaches first NoR, it regains full charge through active means
  • Then moves passively through next myelinated segment

takes about 7ms to move one meter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Neurotransmitter release

A
  • As a result of an action potential, Ca2+ channels in the axon terminal (bouton) will open, Ca2+ will enter the cell
  • Ca2+ causes synaptic vesicles to fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft, a process known as exocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is exocytosis?

A

When NT is released into synaptic cleft after Ca2+ causes the vesicle to fuse with the presynaptic membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Tetrodotoxin and Saxitoxin

A
  • TTX- puffer fish
  • STX/PTX- paralytic shell fish toxin
  • block voltage-gated Na+ channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Batrachotoxin

A
  • BTX- frog
  • Forces Na+ channels to open
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Agitoxin and Betabungarotoxin

A
  • A- Scorpion
  • B-Snake
  • Block voltage-gated K+ channels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Multiple Sclerosis

A
  • person’s immune system makes antibodies that attack myelin, disrupting the conduction of action potentials
  • symptoms vary widely, affecting sensory and/or motor systems depending on which axons are attacked
  • risk is much higher to people exposed to the Epstein-barr virus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly