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KLowe Anesthesia Physiology 1: Cardiovascular Larmon > Lecture 2: Study Guide For Quiz > Flashcards

Lecture 2: Study Guide For Quiz Flashcards

1
Q

Relative to the outside of a cell, is the inside positive or negative in charge?

A

Negative (-90 mV)

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2
Q

Is potassium higher in concentration inside or outside of a cardiac muscle cell?

A

Inside

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3
Q

Is sodium higher in concentration inside or outside of a cell?

A

Outside

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4
Q

What prevents potassium from leaking out of a cell until the concentration is the same on the outside and inside of the cell?

A

Electrostatic force—the build up of negativity on the inside of the cell membrane attracts K+ to stay inside of the cell

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5
Q

What does the Nernst Equation calculate?

A

The equilibrium potential, AKA when the electrical potential (electrostatic force) equals the chemical driving force.

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6
Q

What is the electrical potential (electrostatic force)?

A

It is the build up of negativity on the inside of the cell membrane that attracts K+ to stay inside the cell

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7
Q

What is the chemical driving force?

A

The propensity for K+ to move down its concentration gradient (high to low, from inside to outside of the cell)

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8
Q

What ion makes the major contribution to the resting membrane potential?

A

K+

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9
Q

What ion makes a small contribution to the resting membrane potential?

A

Na+

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10
Q

What ion pump returns ion concentrations back to baseline

A

Na+ - K+ - ATPase pump

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11
Q

How does the Na+ - K+ - ATPase pump contribute to the resting membrane potential?

A

Pumps 3 Na+ OUT for every 2 K+ IN

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12
Q

What ion moves rapidly into the cell during depolarization?

A

Na+

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13
Q

What ion exits the cell to restore the baseline electrical charge in a cell during repolarization?

A

K+

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14
Q

What restores ion concentrations back to their baseline levels?

A

Na+ - K+ - ATPase pump

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15
Q

In what part of the heart are Fast-Response Action Potentials (non-pacemaker action potentials) found?

A
  • Atrial myocardial fibers
  • Ventricular myocardial fibers
  • Purkinje fibers
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16
Q

In what part of the heart are Slow-Response Action Potentials (pacemaker action potentials) typically found?

A
  • SA node

- AV node

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17
Q

What are some of the differences between Non-pacemaker and Pacemaker action potentials?

A
  • RMP (resting membrane potential) is greater in slow-response action potentials
  • Slope of upstroke is greater in fast-response action potentials
  • Amplitude of action potential is greater in fast-response action potentials
  • Overshoot of action potential is greater in fast-response action potentials
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18
Q

What is one thing that is greater in slow-response action potentials?

A

Resting membrane potential

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19
Q

What are three things that are greater in fast-response action potentials?

A
  • Slope of upstroke
  • Amplitude of action potential
  • Overshoot of action potential
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20
Q

What are the 5 phases of the non-pacemaker (fast-response) action potential?

A
  • Phase 0: depolarization
  • Phase 1: partial repolarization
  • Phase 2: plateau
  • Phase 3: repolarization
  • Phase 4: resting membrane potential
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21
Q

Phase 0 (fast-response action potential)

A

Depolarization

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22
Q

Phase 1 (fast-response action potential)

A

Partial repolarization

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23
Q

Phase 2 (fast-response action potential)

A

Plateau

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24
Q

Phase 3 (fast-response action potential)

A

Repolarization

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25
Q

Phase 4 (fast-response action potential)

A

Resting membrane potential

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26
Q

Which ions contribute to the various phases of the fast-response action potential?

A
  • Phase 0: Na+ moves into the cell
  • Phase 1: K+ moves out of the cell
  • Phase 2: slow influx of Ca++ stimulates the C-ICR (large amount of calcium released from the sarcoplasmic reticulum); some K+ moves out of cell to counterbalance
  • Phase 3: K+ moves out of the cell
  • Phase 4: ionic concentrations restored
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27
Q

Phase 0 (ions)

A
  • depolarization

- Na+ moves into the cell

28
Q

Phase 1 (ions)

A

-K+ moves out of the cell

29
Q

Phase 2 (ions)

A

Ca++ moves into the cell slowly through L-type calcium channels; stimulates large amounts of Ca++ to be released by the sarcoplasmic reticulum (C-ICR); some K+ moves out of the cell to counterbalance

30
Q

Phase 3 (ions)

A
  • repolarization
  • K+ moves out of cell (K+ is mainly responsible for repolarization)
  • Na+ channel recovery begins during relative refractory period
31
Q

Phase 4 (ions)

A

-restoration of ionic concentrations

32
Q

What is another name for Phase 2 in a non-pacemaker cell?

A

Plateau phase

33
Q

What is important to know about the plateau phase?

A

-Ventricular contraction persists throughout the action potential, so the long plateau produces a long action potential to ensure forceful contraction of substantial duration

34
Q

Release of a large amount of calcium from the sarcoplasmic reticulum is triggered by entry of which ion?

A

Slow inward entry of Ca++ through L-type calcium channels stimulates C-ICR

35
Q

What is the function of the sarcoplasmic reticulum within a cardiac muscle cell?

A

SR releases a large amount of calcium into the cytosol, which results in binding of myosin to actin and contraction of the myocyte

36
Q

Which ion is the major determinant of the Resting Membrane Potential in cardiac cells?

A

K+

37
Q

What are the various phases found in Pacemaker (slow response) action potentials?

A

-Phase 0: depolarization
-Phase 2: effective refractory period (ERP); very brief
-Phase 3: relative refractory period (RRP); not separated clearly from phase 2
-Phase 4: resting membrane potential
NOTE: phase 1 is ABSENT!

38
Q

Phase 0 (slow-response action potential)

A

Depolarization

39
Q

Phase 1 (slow-response action potential)

A

There is no phase 1 in the slow-response action potential

40
Q

Phase 2 (slow-response action potential)

A

Effective refractory period (ERP); very brief

41
Q

Phase 3 (slow-response action potential)

A

Relative refractory period (RRP); not separated clearly from phase 2

42
Q

Phase 4 (slow-response action potential)

A

Resting membrane potential

43
Q

Which ions contribute to the various phases in the pacemaker action potential?

A
  • Phase 0: depolarization is mainly caused by Ca++ influx
  • Phase 2: K+ efflux causes repolarization
  • Phase 3: K+ efflux causes repolarization
  • Phase 4: Ca++ channel recovery
44
Q

Phase 0 (slow-response) (ions)

A
  • depolarization

- caused by Ca++ influx

45
Q

Phase 2 (slow-response) (ions)

A
  • effective refractory period (ERP)

- K+ efflux causes repolarization

46
Q

Phase 3 (slow-response) (ions)

A
  • relative refractory period (RRP)

- K+ efflux causes repolarization

47
Q

Phase 4 (slow-response) (ions)

A

Resting membrane potential

48
Q

What are the different refractory periods associated with cardiac action potentials?

A
  • Effective refractory period

- Relative refractory period

49
Q

Effective refractory period

A

-K+ efflux causes repolarization

50
Q

Relative refractory period

A

-Ca++ channel recovery

51
Q

What is automaticity?

A

The ability of a focal area of the heart to generate pacemaking stimuli

52
Q

What is diastolic depolarization?

A
  • Inward Na+ (not via typical Na+ channels)
  • Ca++ influx
  • K+ efflux (opposes effects of other ions)
53
Q

What effects on aspects of diastolic depolarization will cause changes in heart rate?

A
  • Autonomic neurotransmitters (i.e.: norepinephrine will increase diastolic depolarization/increase HR; acetylcholine will decrease diastolic depolarization/decrease HR)
  • Electrolyte disturbances will disrupt diastolic depolarization (variable effects, cardiac irritability)
  • Calcium channel blockers will slow diastolic depolarization, and thus decrease HR
54
Q

Which pacemaker region of the heart is typically dominant?

A

SA node

55
Q

What is overdrive suppression?

A

SA node rate of firing is faster than any other node, so it will suppress other nodes from firing

The idea that higher, faster nodal firing prevents all other nodes from firing.

56
Q

What is a sarcomere?

A

A sarcomere is the functional unit of striated muscle.

57
Q

Cardiac cells are arranged in a branching network that is known as what?

A

A syncytium

58
Q

What are T-tubules in a cardiac muscle cell?

A

T-tubules are part of the L-type calcium channel; they allow for communication between extra/intracellular

59
Q

What is the sarcoplasmic reticulum?

A

Intracellular calcium store

60
Q

What is excitation-contraction coupling?

A

The process by which an electrical stimulus triggers the release of calcium by the sarcoplasmic reticulum, initiating the mechanism of muscle contraction by sarcomere shortening

61
Q

What is the trigger for release of large amounts of calcium from the sarcoplasmic reticulum?

A

Slow influx of Ca++ from the interstitial fluid during the action potential triggers the release of Ca++ from the sarcoplasmic reticulum (C-ICR)

62
Q

What is this process called whereby large amounts of calcium are released from the sarcoplasmic reticulum into the cell?

A

C-ICR (calcium-induced calcium release)

63
Q

The presence of what ion allows binding between actin and myosin?

A

Calcium (binds to troponin)

64
Q

What is the function of troponin in the binding between actin and myosin?

A
  • Calcium binds to troponin, causing conformational changes in the troponin-tropomyosin system
  • This releases inhibition on actin and myosin interaction, and the muscle shortens by the sliding filament mechanism
65
Q

What is the sliding filament model?

A

Myosin heads bind to actin, leading to cross-bridge movement (requires ATP) and reduction in sarcomere length, which causes muscle contraction

66
Q

Is ATP required for cardiac muscle relaxation?

A

Yes—ATP is required to unbind myosin from actin. This allows the sarcomere to return to its original, relaxed length.

KLowe Anesthesia Physiology 1: Cardiovascular Larmon (7 decks)

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