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GNUS627/Cardiac/Physiology for Anesthesia > CV - Quiz 2 resting membrane potentials, electrical activity of heart, excitation-contrtaction coupling > Flashcards

CV - Quiz 2 resting membrane potentials, electrical activity of heart, excitation-contrtaction coupling Flashcards

1
Q

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

A

-Negative

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2
Q

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

A

-Potassium is higher inside the cell

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3
Q

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

A

-Sodium concentration is higher outside the cell.

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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

-As the K+ leaves cell, negativity increases on the inside of the cell membrane and electrostatically attracts K+. This electrostatic force prevents K+ from leaving cell.

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5
Q

What does the Nernst Equation calculate?

A

-When chemical driving force (-) electrostatic driving force, NO net movement of K+ = equilibrium.

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6
Q

What ion makes the major contribution to the resting membrane of the cardiac muscle cell?

A

-Potassium is the major determinant of the Resting Membrane Potential.

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7
Q

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

A

-Sodium

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8
Q

What ion pump returns ion concentrations back to baseline?

A

-The Na+-K+-ATPase Pump

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9
Q

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

A

-For every 3 Na+ going OUT of the cell 2 K+ would be going INTO the cell.

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10
Q

What ion moves rapidly into a cell during depolarization?

A
  • Na+
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11
Q

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

A
  • +K
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12
Q

What restores ion concentrations back to their baseline levels?

A
  • Na+-K+- ATPase Pump
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13
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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14
Q

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

A
  • Sinoatrial node and atioventricular node
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15
Q

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

A
  • (Fast response = non-pacemaker) and (Slow-response = pacemaker)
  • RMP = Slow > Fast; Slope of upstroke = Fast > Slow; Amplitude of action potential = Fast >Slow; Overshoot of action potential = Fast > Slow
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16
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 = Repolarizaiton
  • Phase 4 = Resting Membrane Potential
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17
Q

Which ions contribute to the various phases?

A
  • Phase 0 = Na+
    -Phase 1 = Inactivation of Na+ channels ends transient outward K+ current
    -Phase 2 = Slow inward Ca++ currents ( L-type calcium channels) Outward K+ currents.
    -Phase 3 = Outward K+ (repolarization) Na+ channel recovery begins during relative refractory period.
    -Phase 4 = Na+, K+-ATPase Na+-Ca++ exchanger
    ATP-driven Ca++ Pump
18
Q

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

A
  • Plateau
19
Q

Release of a large amount of calcium from the Sarcoplasmic Reticulum is triggered by entry of which ion?

A

small amounts of Calcium

20
Q

What is the function of the Sarcoplasmic Reticulum within a cardiac muscle cell?

A

regulate intracellular calcium concentration

21
Q

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

A

Potassium

22
Q

What are the various phases found in Pacemaker (Slow Response) Action Potentials?

A

0,(no phase 1), 2 (very brief),3,4

23
Q

Which ions contribute to the various phases in the Pacemaker Action Potential?

A

Zero - calcium influx
Three - Potassium influx (repolarized), low Ca
Four - Na, lower K+ and elevated Ca

24
Q

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

A
  • Effective or Absolute (ERP) - no action potential can happen
  • Relative (RRP)
25
Q

What is automaticity?

A

Ability of focal area of heart to generate pacemaking stimuli

26
Q

What is diastolic depolarization?

A

slow iinward leakage of Na+ through funny channels, Ca++ influx, K+ efflux

27
Q

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

A 
-Increasing
     sympathetic stimulation
     Muscarinic receptor antagonist
     B-Adrenoceptor agonists
     Circulating catecholamines
     Hypokalemia
     Hyperthyrodism
     Hyperthermia
-Decreasing 
     Parasympathetic stimulation
     Muscarinic receptor agonists
     B-blockers
     Ischemia/hypoxia
     Hyperkalemia
     Sodium and calcium channel blocker
     Hypothermia
28
Q

Which pacemaker region of the heart is typically dominant?

A

SA node

29
Q

What is Overdrive Suppression?

A

2ndary pacemeakers are hyperpolarized when driven beyond their set rate

30
Q

What is a sarcomere?

A

the basic contractile unit of myocite, between two Z-lines

31
Q

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

A

functional syncytium

32
Q

What are T-tubules in a cardiac muscle cell?

A

openings from sarcolemma that run deep. Let ions (Na+, Ca++) exchange between extra and intracellular compartments

33
Q

What is the Sarcoplasmic Reticulum?

A

extensive branching tubular netwrok to regulate intracellular calcium, storage and realease of calcium

34
Q

What is Excitation-Contraction coupling? pg 43 in book

A

coupling between myocyte action potentials and contraction

35
Q

What is the trigger for release of large amounts of calcium from the Sarcoplasmic Reticulum?

A

small amounts of calcium influx causes release of large amount of calcium from sarcoplasmic reticulum

36
Q

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

A

Calcium-Induced Calcium Release

37
Q

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

A

Calcium

38
Q

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

A

To inhibit actin and myosin from binding

39
Q

What is the Sliding Filament Model ?

A

ratcheting of myosin heads along the actin filaments

40
Q

Is ATP required for cardiac muscle relaxation?

A

Yes

GNUS627/Cardiac/Physiology for Anesthesia (12 decks)

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