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Physiology 1 > CV Quiz 2 > Flashcards

CV Quiz 2 Flashcards

1
Q

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

A
  • Increases HR:
    • SNS stimulation
    • Muscarinic receptor antagonist
    • B-adrenoreceptor agonist
    • Circulating catecholamines
    • Hypokalemia
    • Hyperthyroidism
    • Hyperthermia
  • Decreases HR:
    • PNS stimulation
    • Muscarinic receptor agonists
    • B-blockers
    • Ischemia/hypoxia
    • Hyperkalemia
    • Na/Ca channel blockers
    • Hypothermia
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2
Q

What does the Nernst Equation calculate?

A

Equilibrium potential- electrical potential needed to keep an ion from diffusing down its chemical gradient thereby changing its concentration across membrane

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3
Q

What are T-tubules in a cardiac muscle cell?

A

Deep invaginations of the external sarcolemma that permits intra/extra-cellular ion exchange deep within myocyte during de/re-polarization

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4
Q

What are the various phases found in Pacemaker (Slow Response) Action Potentials? Which ions contribute to the various phases?

A
  • Phase 0 (Upstroke of AP)
    • Ca influx
  • Phase 3 (Repolarization)
    • K efflux
  • Phase 4 (Spontaneous depolarization)
    • Na and Ca influx
    • K efflux
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5
Q

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

A

SA and AV node

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6
Q

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

A

Pumps 3 Na out and 2 potassium into cell, maintaining their concentration gradients across the membrane

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7
Q

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

A

Functional syncytium

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8
Q

What is a sarcomere?

A

Contractile unit of the myocyte

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9
Q

Which pacemaker region of the heart is typically dominant?

A

SA node

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10
Q

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

A

Regulate intracellular Ca

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11
Q

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

A

K

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12
Q

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

A

Potassium

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13
Q

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

A

Small amount of calcium

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14
Q

What is the Sarcoplasmic Reticulum?

A

Branching, tubular network that surrounds myofilaments that regulates intracellular Ca concentration

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15
Q

What ion pump returns ion concentrations back to baseline?

A

Na, K-ATPase Pump

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16
Q

Is ATP required for cardiac muscle relaxation?

A

Yes

17
Q

What is automaticity?

A

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

18
Q

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

A

Plateau

19
Q

Is the inside of a cell postive or negative?

A

Negative

20
Q

What are the 5 phases of the Non-pacemaker (Fast-Response) action potential? Which ions contribute to the various phases?

A
  • Phase 0 = Depolarization
    • Na Influx
  • Phase 1 = Partial repolarization
    • Na Stops, K efflux
  • Phase 2 = Plateau
    • Ca influx (L-type Ca channels), K efflux
  • Phase 3 - Repolarization
    • K efflux
  • Phase 4 = Resting membrane potential
    • Ratio of intra- to extra-cellular K
21
Q

What is the Sliding Filament Model?

A
  1. Ca binds TN-C
  2. Cross-bridge formation between actin and myosin
  3. ATP hydrolysis
  4. Thin filaments slide over myosin during cross-bridge cycling
  5. Sarcomere shortens
  6. Muscle contraction occurs
22
Q

What is diastolic depolarization? What ions are associated with it?

A

Ionic mechanisms for initiating spontaneous depolarization in a pace-making cell

  • Na/Ca influx
  • K efflux
23
Q

What is Overdrive Suppression?

A

Automaticity of pacemaker cells becomes depressed after a period of excitation at a high frequency

24
Q

What restores ion concentrations back to their baseline levels?

A

Na, K-ATPase pump

Na/Ca Exchanger

ATP-driven Ca pump

25
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

26
Q

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

A

Ca binds to troponin to initiate a cross-bridge formation between Myosin and Actin

27
Q

What ion makes a small contribution to RMP?

A

Na

28
Q

What ion moves rapidly into a cell during depolarization?

A

Na

29
Q

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

A

Outside

30
Q

What is Excitation-Contraction coupling?

A

When AP causes depolarization of a myocyte

31
Q

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

A
  • Atrial and ventricular myocardial fibers
  • Purkinje fibers
32
Q

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

A

Potassium

33
Q

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

A

Inside

34
Q

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

A

Ca

35
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 (CICR)

36
Q

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

A
  1. Absolute (effective) refractory period
    * No new AP can be generated
  2. Relative refractory period
    * Very strong stimulus needed to cause AP
37
Q

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

A
  • Resting membrane potential- Slow > fast
  • Slope of upstroke- Fast > slow
  • Amplitude of action potential- Fast > slow
  • Overshoot of action potential- Fast > slow
38
Q

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

A

Ca

Physiology 1 (6 decks)

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