Brainscape's Knowledge GenomeTM

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


See full index

Cognition & Senses - wk 1 > membrane potential and neuronal action potentials > Flashcards

membrane potential and neuronal action potentials Flashcards

1
Q

electrical signals necessary for neural function are mediated by the flow of ions through:

A

aqueous pores in the nerve cell membrane

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

what are one of the principle theraputic targets of drugs

A

ion channels

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

what is membrane potential

A

charge difference across the plasma membrane

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

the plasma membrane acts as a:

A

capacitor

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

what is a capacitor

A

two conductive surfaces (ions in solution) separated by a non-conductive surface (lipid bilayer)

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

when ion channels open, current is allowed:

A

to flow across the plasma mebrane potential

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

what is the resting membrane potential of a neuron

A

-70mV

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

what is depolarization

A
  • any positive change in the membrane potential
  • inside of the cell becomes more positive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is hyperpolarization

A
  • any negative change in the membrane potential
  • inside of the cell becomes more negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is hyperpolarization

A
  • any negative change in the membrane potential
  • inside of the cell becomes more negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

is a chloride channel (Cl- flows into neuron) depolarization or hyperpolarization

A

hyperpolarization

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

what is Ohm’s law

A
  • describes the relationship between ion flow (current) and membrane voltage
  • voltage (V) = current (I) x resistance (R)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the amount of current is ____ ____ to the voltage across the membrane

A

directly proportional

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

what dictates the amplitude of ion flux

A

Vm (membrane potential)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the membrane potential

A

cell interior is electrically negative relative to the exterior

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

what are the two forces that determine the asymmetric equilibrium distribution of ions across the plasma membrane

A

electrical (membrane potential) and chemical (concentration gradient) forces = electrochemical gradient

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

how is equillibrium achieved

A

when the tendency of an ion to move down its concentration gradient is exactly counter-balanced by an opposing electrical gradient, resulting in no net ion flux

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

what is electrical gradient

A

ion diffusion is affected by electrical charge differences and they tend to move toward opposite charge

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

what is chemical gradient

A

ions move by diffusion from high to low concentration

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

what is the main determinants of the resting membrane potential

A

the differential distribution of ions across the plasma membrane

21
Q

Na+/K+ ATPase

A

contributes only a small amount of the resting membrane potential

22
Q

K+ leak channels

A

relatively selective permeability of the plasma membrane to K+ contributes most of the resting membrane potential

23
Q

what is the equilibrium (reversal) potential , Eion

A
  • defined as the membrane potential at which the direction of ion flow through a particular channel reverses direction
  • enables one to predict which direction ions will flow
  • determined by the intracellular and extracellular concentration of each ion
24
Q

what is the nerst equation used for

A

to calculate the equilibrium potential for a given set of ionic conditions

25
Q

what is needed to pull K+ into the cell against outward concentration gradient

A

very negative cell interior

26
Q

what is needed to push Na+ out of the cell against inward concentration gradient

A

very positive cell interior

27
Q

what is an action potential

A
  • rapid change in membrane potential
  • occurs when a “stimulation” of the nerve cell membrane depolarizes the membrane enough to allow Na+ channels to to open (threshold ~ -50mV)
28
Q

what are voltage-gated NA+ channels responsible for

A

depolarizing membrane and (inward current) conduction of action potential

29
Q

what are the voltage-gated K+ channels responsible for

A

repolarization following action (outward currents) potential (returning towards resting potential)

30
Q

what are Na+/K+ ATPase and K+ leak channels responsible for

A

sets resting potential and returns membrane potential back to resting during refractory period

31
Q

when does depolarization occur

A

when ligand-gated nonselective cation channels at the post-synaptic membrane generate small excitatory depolarizing stimuli

32
Q

what does the small excitatory depolarization stimuli allow

A

Na+ to begin to pass into the cell and the depolarization spreads to the axon hillock and initital segment

33
Q

why does the AP start at the axon hillock and initial segment

A

the initital segment contains high conc. of voltage-gated sodium channels

34
Q

what are EPSP (excitatory post-synaptic potentials)

A
  • positive charges into the cell; graded potential
  • depolarizations are excitatory
35
Q

what are IPSP (inhibitory post-synaptic potentials)

A
  • negative charges into the cell; graded potential
  • hyperpolarizations are inhibitory
36
Q

what is the threshold

A

depolarizations to approx. -55 to -50 mV is required for action potential

37
Q

what is sodium channel inactivation important for

A

unidirectional AP conductance

38
Q

what are the 6 phases of the action potential

A
  1. threshold
  2. rising phase (depolarization)
  3. peak (Na+ channels inactivate)
  4. falling phase (hyperpolarization)
  5. undershoot
  6. recovery
39
Q

what is the absolute refractory period

A

time immediately after action potential which another AP cannot occur (due to Na+v channel inactivation and delay in K+v channel closing)

40
Q

what is the relative refractory period

A

time after AP during which greater stimulation is necessary to cause another AP

41
Q

how does the AP travel down the axon

one spot

A
  • some Na+ ions flow in
  • membrane potential rises to ~50 mv
  • reaches threshold for voltage-gated Na+ channels
  • voltage gated Na+ channels activated
  • Na+ flowing in - membrane potential continutes to rise rapidly
  • reaches threshold for voltage-gated K+ channels - they open
  • Na+ channels inactivate and close
  • K+ flowing out rapidly - membrane potential drops (repolarization)
  • membrane potential drops below -70mV
  • K+ channels inactivate
  • Na+ channels reset
  • K+ channels reset
42
Q

what happens along the whole axon during the depolarization phase

A

as the membrane potential rises in this spot, the membrane potential directly next to it is also affected

43
Q

what happens along the whole axon along the repolarization phase

A

as the membrane potential falls in this spot, the membrane potential directly next to it is also affected and follows

44
Q

what factors will improve axon potential conduction velocity and distance

A
  • increase the density of Na+v channels
  • increase the diameter of the axon
  • insulation (myelin)
45
Q

what is myelin

A
  • schwann cells (glia) wrap around the axon and acts as insulation
  • conduction jumps from node to node (saltatory conduction)
46
Q

what is saltatory conduction

A
  • metabollically efficient - ion movements limited to nodal regions
  • 100x faster conduction velocities
47
Q

what are the consequences/benefits of axon myelination

A
  • less “leaky” = more downstream
  • lower capacitance = more downstream current
  • have highly increased concentration of Na+ channels at the nodes
48
Q

summation - spatial vs temporal

A
  • spatial - E1 and E1 occur at different spots one right after the other
  • temporal - E1 and E2 ontop of each other

Cognition & Senses - wk 1 (13 decks)

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