Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Psyco 275 > Resting Membrane and Action Potentials > Flashcards

Resting Membrane and Action Potentials Flashcards

1
Q

What is a neuron at rest?

A

Unstimulated/inactive

Can change when excited by input

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

How does a negative charge build-up inside the cell?

A

The membrane bilayer is selectively permeable
Ions cannot cross easily which results in a polarized membrane (-70 mV)
Ions are unequally distributed across the membrane

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

How do we record membrane potential?

A

Use intracellular and extracellular electrodes to detect the difference between the inside and outside of cells

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

What is the ionic distribution outside of the cell?

A

Higher [Na+] outside of the cell

  • the membrane extremely resists passage
  • driven inside cell by electrostatic forces and concentration gradient

Higher [Cl-] concentration outside of the cell

  • membrane slightly resists passage
  • more at equilibrium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the ionic distribution inside of the cell?

A

Higher [K+] inside of the cell

  • driven inside by electrostatic pressure and outside by a concentration gradient
  • membrane is highly permeable to K+ because they are more leaky channels

Negatively charged proteins inside
-cannot cross the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the factors that maintain resting potential?

A

Concentration gradient
Electrostatic pressure
Passive forces
Active forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a concentration gradient?

A

Tend to equally distribute

Move from high to low concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is electrostatic pressure?

A

Like repels like

Opposites attract

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

What are passive forces?

A

Random motion due to selective permeability to ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are active forces?

A

Sodium-potassium pumps; maintain the stability of resting membrane potential
Re-distribution of ions

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

How do sodium-potassium pumps provide long-term maintenance of resting membrane potential?

A

Active transporter

Maintains equilibrium potential by continuously transferring 3Na+ out and 2K+ in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do postsynaptic potentials create excitatory signals?

A

Excitatory neurotransmitters bind and cause rapid change to the postsynaptic cell
Causes depolarization of the cell (cell becomes less negative)
An excitatory postsynaptic potential increases the likelihood of an action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an EPSP?

A

Excitatory postsynaptic potential
Graded response
Bigger stimulation = bigger PSP
larger positive ion influx = larger EPSP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do postsynaptic potentials create inhibitory signals?

A 
Inhibitory neurotransmitters bind and cause rapid change to the postsynaptic cell
Causes hyperpolarization (cell becomes more negative) 
An inhibitory postsynaptic potential decreases the likelihood of an action potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an IPSP?

A

Inhibitory postsynaptic potential

Large negative ion influx = larger IPSP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a graded response?

A

The amplitude of the signal proportional to stimulus intensity
Passive decay over space and time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a rapid transmission?

A

Instantaneous rate of transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does the integration of PSPs help the cell depolarization reach threshold?

A

One EPSP will not generate an action potential

We need to add or combine incoming signals within a given neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the threshold of excitation?

A

Synapses closer to the axon hillock have a larger effect on firing due to the incremental transmission of far away PSPs
The integration of inputs must result in about -65 mV at hillock for an action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is spatial summation?

A

Occurs at axon initial segment
Integration of PSPs across postsynaptic locations
Local EPSPs and IPSPs occurring simultaneously combine to amplify or cancel out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is temporal summation?

A

Integration across time on the same synapse

Multiple rapid inputs from the same presynaptic site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an action potential?

A

Reversal of membrane potential by stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why doesn’t an action potential degrade?

A

Does not degrade along the length of the axon due to the voltage-gated channels

24
Q

What type of response is an action potential?

A

All or nothing is the membrane depolarizes to the threshold voltage

25
Q

How are action potentials affected by higher or longer stimulation?

A

The firing frequency increases

26
Q

What happens to the action potential when it just meets the threshold?

A

There are fewer action potentials produced

27
Q

What happens to the action potential when it goes way about the threshold?

A

There are many action potentials produced

28
Q

What channels generate and propagate action potentials?

A

Voltage-gated sodium channels

29
Q

Where are voltage-gated ion channels found?

A

Along the axon

30
Q

When do voltage-gated ion channels open?

A

in response to membrane potential depolarization

31
Q

When do voltage-gated ion channels close?

A

Close to continued depolarization

32
Q

What happens when sodium channels open?

A

Sodium rushes into the cell based on the electrostatic and concentration gradient
The membrane potential reaches +50 mV

33
Q

When do sodium channels close?

A

When depolarization reaches a threshold

34
Q

What happens when potassium channels open?

A

Potassium rushes out of the cell based on the electrostatic and concentration gradient
Membrane repolarizes and becomes slightly hyperpolarized
These channels close gradually

35
Q

How is membrane potential reestablished?

A

By random motion of ions and the sodium-potassium pump

36
Q

What are the differences between PSPs and APs?

A

EPSPs/IPSPs

  • decremental over space and time
  • fast
  • passive

APs

  • non-decremental
  • conducted more slowly than PSPs
  • passive and active
37
Q

What is the absolute refractory period?

A

Voltage-gated sodium channels are inactivated for about 1 msec post-AP initiation
Cannot start a new AP in the same location on the axon

38
Q

What is the purpose of the absolute refractory period?

A

Prevents backwards movement of the AP

39
Q

What is the relative refractory period?

A

Happens during the after hyperpolarization
Requires larger than threshold stimulus to initiate new AP
More intense stimulation can overcome hyperpolarization to increase the firing rate

40
Q

How are action potentials conducted across the axon?

A

A row of voltage-gated sodium channels creates a domino effect that causes a wave of depolarization
Spreading can occur in two directions
-anterograde
-retrograde

41
Q

What is orthodromic conduction?

A

Anterograde movement

-hillock to boutons

42
Q

What is antidromic conduction?

A

Retrograde movement

-boutons to hillock

43
Q

What is the velocity of axonal conduction of APs?

A

Large diameter = faster because there is less friction
Myelinated = faster
Large are myelinated = really fast

44
Q

What is saltatory conduction?

A

AP jumps from node to node
Requires less energy
Sodium channels are only located on nodes

45
Q

What is conduction in myelinated axons like?

A

Faster action potentials
Passive (rapid and decremental) from node to node
-diminished before the next node but is enough to open the next sodium channel

46
Q

Are all axons myelinated?

A

Long, peripheral nerves

Cells spanning locations within the CNS

47
Q

What does myelin degeneration do?

A

Impairs AP conduction

48
Q

What does MS attack?

A

Immune system attacks myelin

  • schwann cells
  • oligodendrocytes
49
Q

What are the steps of chemical transmission?

A
  1. AP reaches the end of the axon terminal
  2. Calcium enters the cell
  3. Presynaptic density release neurotransmitter into the cleft via exocytosis
  4. Neurotransmitter binds receptors on post synaptic density
  5. Receptors influence post synaptic neurons
  6. Neurotransmitter degradation/recycling
50
Q

What are the 5 types of synaptic contacts?

A 
Axodendritic 
Axosomatic 
Dendrodendrtic 
Dendroaxonic 
Axoaxonic
51
Q

What is an axodendritic synaptic contact?

A

Axon to dendrite

Most common

52
Q

What is an axosomatic synaptic contact?

A

Axon to soma

53
Q

What is a dendrodendritic synaptic contact?

A

Dendrite to dendrite
Reciprocal
-can be transmitted in either direction

54
Q

What is a dendroaxonic synaptic contact?

A

Dendrite to axon

55
Q

What is an axoaxonic synaptic contact?

A

Axon to axon
Mediate presynaptic inhibition or facilitation
-selectively influence synapse rather than entire neuron

56
Q

What is a directed synapse?

A

Site of neurotransmitter release close to postsynaptic contact
Most common

57
Q

What is an undirected synapse?

A

The site of release and contact is far
Has varicosities
Common for monoamines
The neuroendocrine system releases neurohormones into the bloodstream

Psyco 275 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions