Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

FHB Exam 1 - Cardiovascular Physiology > Lecture 1 - Neuronal Action Potential > Flashcards

Lecture 1 - Neuronal Action Potential Flashcards

1
Q

Which vertebrate cell has the longest duration?

  1. Motor
  2. Skeletal
  3. Cardiac Ventricle
A

Cardiac ventricle

  • duration is fast, about 200 milliseconds
  • heart has long AP to protect it from additional AP’
  • thus cannot be activated as quickly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the term for the response that does NOT generate an AP because the voltage is not large enough?

A

Sub threshold response

  • decreases in amplitude with distance
  • change in membrane potential not sufficient for action potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the length constant?

A

Distance over which a sub threshold depolarization (local response) will spread & influence the next membrane

  • larger length constant = MORE RAPID CONDUCTION
    (fires an AP)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When you decrease Rm, what happens to the space constant? What about decreasing Ri?

A
  1. decrease Rm = decrease length constant

2. decrease Ri = INCREASE length constant

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

What is Rm and Ri?

A 
Rm = membrane resistance
Ri = internal resistance (or Ra)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

With a large axonal diameter, is the length constant large or small?

A

length constant is LARGE since Ri is LOW(internal resistance)

-

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

As distance increases from the current source, what happens to the sub threshold voltage?What manner does this decay (graph wise)

A

DECREASES (decays) with increasing distance from source

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

Larger diameter axons have lower or higher membrane and internal resistance? (rm and Ri)

A

Large diamter = LOWER resistance than smaller axon

  • but since Ri is squared, it decreases more than rm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Large diameter results in _____ conduction

A

Faster conduction velocity

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

What determines how easily an axon can conduct an AP?

A

Space constant

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

What determines the space constant?

A

membrane Resistance

internal Resistance

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

What occurs once an area of membrane is activated by an action potential?

A

REVERSAL OF MEMMBRANE POLARITY

inside becomes more positive than outside
- originally NEG inside

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

Local current flow occurs between activated (depolarized) and inactive regions, activating ______ channels to depolarize the next segment of membrane and initiating an AP/

A

NA channels!!!

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

A stimulus is a ____ or ____ response.

A

All or none

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

Upstroke of the action potential graph is caused by what? Repolarization is caused by what?

A
  1. Na activation (opening of M channels)

2. delayed increase in K+ conductance and inactivation of Na channels (closing of h gates)

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

Where is the only place AP’s occur?

A

Nodes of Ranvier

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

An action potential occurs between the E of what two ions?

A

Ena and Ek

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

Repolarization turns off what channel conductance completely?

A

K+ (deactivated)

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

Describe the gating properties of Na channel at the following stages:

  1. Resting
  2. Activated
  3. Inactivated
A
  1. resting: M closed, h open
  2. Activated: both open, NA INFLUX (h slowly closing)
  3. Inactivated: M open, h closed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the time required to reset the channel from inactivated state back to resting state?

A

Recovery from Inactivation

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

Recovery from inactivation requires what?

A

Repolarization

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

Gating kinetics for Na and K both depend on what?

A

Time and Voltage

23
Q

What gates due NOT have inactivation gates?

24
Q

What channels respond RAPIDLY to depolarization?

A

Na+ channels

25
What occurs during regenerative depolarization?
1. Na+ moves into the cell down its electrical & conc gradient 2. DEPOLARIZE membrane to Ena 3. increase Na permeability 4. causing FURTHER DEPOLARIZATION
26
What channels close rapidly at depolarized (positive) voltages?
Na+ - inactivation is time and voltage dependent
27
What is the basis for refractory periods?
Voltage-dependent inactivation of Na+ channels
28
Recovery from inactivation requires what?(to reach resting state)
1. time | 2. Negative voltages (repolarization)
29
What channels remain open with maintained depolarization of the membrane? When do these channels completely deactivate?
K+!!! - no inactivation - completely deactivate with DEPOLARIZATION
30
What flows into the cell, what flows out?
NA in, K+ out (down its conc gradient) Na moves down its electric and chemical gradient
31
Depolarization of the membrane potential toward Ek causes the potential to go more negative than RMP, called:
HYPERPOLARIZATION
32
What is the time during which a stimulus CANNOT elicit a regenerative response? When does this occur?
ABSOLUTE refractory period - occur during Na+ inactivation during depolarization and increase in membrane potential to more positive values
33
What is the time during which a stimulus CAN elicit a regenerative response/AP? When does this occur?
1. Relative Refractory Period 2. when membrane potential RE-polarizes, Na+ channels recover from inactivation and reach RESTING state HYPERPOLARIZATION
34
As the voltage becomes more positive, the number of Na channels/conductance increases or decreases?
Decreases! - at -60mV 50% of sodium channels open BUT at -90 --> 100% are open
35
Conduction can be slowed causing muscle weakness. This would be due to loss of what channels?
Sodium channels
36
Refractory periods in nerve (and heart) are solely based on voltage-depends characteristic of what channels?Which specific gate?
1. SODIUM! 2. H gate!!! - inactivated at positive voltages re-polarization = Na+ channels recover
37
What cation modulates Sodium channel activity?
CALCIUM!
38
If membrane bound calcium increases, what happens to sodium channels?
BECOME INACTIVATED - believe that area has become more positive - H gates CLOSE!
39
What occurs to the following during HYPERCALCEMIA: 1. calcium concentration 2. Na+ threshold 3. Membrane excitability
1. increases 2. increases 3. decreases membrane excitability
40
How can hypercalcemia be tested clinically?
REFLEX TEST - slower/muted reflexes are a sign
41
How can hypocalcemia be tested clinically?
REFLEXES - hyper-reflexivity is a result of increased membrane excitability due to low calcium conc.
42
What occurs to the following during HYPOCALCEMIA: 1. calcium concentration 2. Na+ threshold 3. Membrane excitability
1. decreases 2. decreases 3. INCREASES membrane excitability
43
What occurs to the following during Hyperventilation: 1. CO2 concentration 2. respiratory state 3. Membrane excitability What is a sign?
1. decreased CO2 2. Respiratory Alkalosis 3. Increased membrane excitability (irritable)
44
What occurs to the following during Hypoventilation: 1. CO2 concentration 2. respiratory state 3. Membrane excitability What is often the cause?
1. more CO2 2. Respiratory acidosis (co2 binds to water to make acid) 3. decreased membrane excitability ex: barbituates, foreign object in trachea
45
What occurs during Hyperkalemia to the following: 1. RMP 2. Na+ channels 3. inward Na+ current & conduction 4. SIGNS & SYMPTOMS
1. more positive resting membrane potential (increase K+) 2. Na+ channels inactivated 3. inward Na+ DECREASED = slower conduction 4. Slow mentation, muscle weakness
46
What is the normal serum potassium level?
3-5mmol - higher = hyperkalemia
47
Potassium levels often change with what diseases?
Renal Failure - Hyperkalemia occurs
48
What allows us to have significantly greater conduction velocity?
Myelination of axons
49
What increases conduction more, myelination or axon diameter?
MYELINATION - unmyelinatd axons 100 times greater in diameter
50
What is the only place not covered by Schwann cells?
Node of Ranvier
51
Myeline sheath increases what? This increases or decreases the length constant and conduction velocity?
Rm - increases length constant - increases conduction velocity
52
What is internal distance between 2 nodes of Ranvier?
1-2 mm
53
Na+ channels are concentrated where? What is found here? This type of conduction is called:
1. Nodes of Ranvier 2. Action POtentials 3. SALTATORY CONDUCTION
54
What diseases destroy myelination and slow neuronal conduction?
Diabetic neuropathies Multiple Sclerosis

FHB Exam 1 - Cardiovascular Physiology (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions