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(1) Physiology > S3_L1: Cardiac Electrophysiology > Flashcards

S3_L1: Cardiac Electrophysiology Flashcards

1
Q

TRUE OR FALSE: The striations of cardiac muscles are similar to that of skeletal muscles

A

True

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2
Q

How many phases does the fast response have?

A

5

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3
Q

What is the effect of tetrodotoxin to the fast response?

A

Phase 1 disappears

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4
Q

TRUE OR FALSE: The effective refractory period is from start of phase 0 to 1/3 of repolarization.

A

True

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5
Q

TRUE OR FALSE: If a pacemaker’s frequency of discharge is faster, it can be a true pacemaker

A

True

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6
Q

TRUE OR FALSE: The heart’s conducting system never allows
retrograde transmission of impulses

A

True

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7
Q

TRUE OR FALSE: Faster HR greatly decrease diastolic filling time

A

True

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8
Q

What is the effect of catecholamines to the heart?

A

(+) chronotropic and inotropic effect

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9
Q

This impinges in the working cardiac muscles.

A

Purkinje fibers

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10
Q

What is the effect of ACh to HR?
A. Tachycardia
B. Bradycardia

A

B. Bradycardia

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11
Q

If the threshold potential is made less negative, what happens to the heart rate?
A. Tachycardia
B. Bradycardia

A

B. Bradycardia

If the slope of a pacemaker/prepotential is decreased, the threshold potential will be less steep and it will be reached after a
longer time, therefore the overshoot will also be at a later time causing the heart rate to be decreased.

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12
Q

What happens if the phase 4 slope of the pacemaker potential is made steep?
A. Tachycardia
B. Bradycardia

A

A. Tachycardia

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13
Q

If the SA Node is blocked, what will be the pacemaker?

A

AV node

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14
Q

The normal or true pacemaker that is at the junction of the right atrium and superior vena cava. It is a remnant of the sinus venosus.

A

SA Node

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15
Q

TRUE OR FALSE: Cardiac muscle cells branch and interdigitate

A

True

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16
Q

Where are the T Systems of Cardiac muscles located?

A

At the z lines

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17
Q

This exhibits the slow response action potential.

A

AV node

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18
Q

TRUE OR FALSE: The slow response has an absent plateau

A

True

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19
Q

In the fast response, what explains phase 0?
A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels
B. Opening of Ca++ channels
C. Na+ influx
D. Closure of Na+ and opening of K+ channels
E. K+ efflux

A

C. Na+ influx

20
Q

In the fast response, what explains phase 4?
A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels
B. Opening of Ca++ channels
C. Na+ influx
D. Closure of Na+ and opening of K+ channels
E. K+ efflux

A

A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels

21
Q

In the fast response, what explains phase 3?
A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels
B. Opening of Ca++ channels
C. Na+ influx
D. Closure of Na+ and opening of K+ channels
E. K+ efflux

A

E. K+ efflux

22
Q

In the fast response, what explains phase 2?
A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels
B. Opening of Ca++ channels
C. Na+ influx
D. Closure of Na+ and opening of K+ channels
E. K+ efflux

A

B. Opening of Ca++ channels

23
Q

In the fast response, what explains phase 1?
A. Return back to RMP, Na+ K+ ATPASE pump ions back, closure of K+ channels
B. Opening of Ca++ channels
C. Na+ influx
D. Closure of Na+ and opening of K+ channels
E. K+ efflux

A

D. Closure of Na+ and opening of K+ channels

24
Q

Muscles that exhibits the fast response action potential.

A

Ventricular muscles

25
Q

In the slow response, what completes the prepotential?

A

Ca++ via transient Ca++ channels

26
Q

In the slow response, what initiates the prepotential?

A

Opening of H channel; caused by funny current

27
Q

Determine the corresponding descriptions of the refractory period in cardiac excitability

  1. Vulnerable period of the heart
  2. May or may not be able to stimulate the heart
  3. Cannot stimulate the heart regardless of mV
  4. Going back to RMP
  5. Electric shock must not be given at this period or else, V-tach (ventricular tachycardia) or V-fib (ventricular fibrillation) or asystole (flatline) could occur
  6. Onset of depolarization to 1/3 of phase 3
    (repolarization)

A. Absolute (Effective) Refractory Period
B. Relative Refractory Period
C. Supranormal Period
D. Full Time Recovery

A
  1. C
  2. B
  3. A
  4. D
  5. C
  6. A
28
Q

Enumerate the 3 factors that determine pacemaker discharge frequency

A
  1. Rate or slope of depolarization during phase 4
  2. Level of threshold potential which must be attained
  3. Magnitude of resting potential
29
Q

A low stroke volume results to a low (1)___ and high (2)___

A
  1. Cardiac output
  2. Heart rate
30
Q

The resting phase of the heart where ventricular filling happens. The time of this phase decreases when the heart beats faster

A

Diastole

31
Q

Bundle branches that divide into left anterior and left posterior fascicles. These fascicles will end up as the Purkinje system

A

Left bundle branches

32
Q

Arrange the following in the correct order of the conducting system of the heart

Choices: AV Node, Internodal pathways toward the atria, posterior internodal pathway of Thorel, Purkinje fibers, Bundle of His, middle internodal pathway of Wenckebach, Bundle branches, SA Node, anterior internodal pathway of Bachmann

A
  1. SA Node
  2. Internodal pathways toward the atria
  3. anterior internodal pathway of Bachmann
  4. middle internodal pathway of Wenckebach
  5. posterior internodal pathway of Thorel
  6. AV Node
  7. Bundle of His
  8. Bundle branches
  9. Purkinje fibers
33
Q

Determine the corresponding descriptions of the components in the electrocardiogram (ECG)

  1. ventricular repolarization which is in line
    with phase 3 of fast response
  2. ventricular filling; found in diastole
  3. atrial depolarization which is in line with
    atrial muscle depolarization
  4. ventricular depolarization which is in line
    with fast response AP in ventricles

A. P wave
B. QRS
C. T wave
D. U wave

A
  1. C
  2. D
  3. A
  4. B
34
Q

Enumerate the 4 factors that affect pacemaker activity

A
  1. Acetylcholine and vagal influence
  2. Sympathetic activity
  3. Temperature
  4. Ions
35
Q

The Anterior Tract of Bachmann goes to the ___.

A

Left atrium

36
Q

Determine the corresponding descriptions of the components of the conduction system of the heart

  1. conduction velocity is fastest & has the largest action potential
  2. automatic cell with the greatest auto-rhythmicity
  3. additional and separate fibers that bypass
    the bundle of His & connect atria &
    ventricles
  4. beneath the endocardium on the (R) side of the atrial septum
  5. penetrates the heart skeleton (trigone) & enters the ventricular septum

A. Sinoatrial node
B. Atrioventricular node
C. Bundle of His
D. Purkinje fibers
E. Posterior tract of Thorel
F. Bundle of Kent

A
  1. D
  2. A
  3. F
  4. B
  5. C
37
Q

Determine the corresponding descriptions of the components of the conduction system of the heart

  1. its transmission is always anterograde
  2. converges to the AV Node
  3. arise from bundle branches
  4. single bundle of specialized tract
  5. may not be sufficient to excite the next zone causing a first degree heart block

A. Sinoatrial node
B. Atrioventricular node
C. Bundle of His
D. Purkinje fibers
E. Posterior tract of Thorel
F. Bundle of Kent

A
  1. B
  2. E
  3. D
  4. C
  5. B
38
Q

With regards to the layers of the heart, depolarization and repolarization occur from?

A

Depolarization: from endocardium to epicardium
Repolarization: from epicardium to endocardium

39
Q

Determine the corresponding descriptions of the types of cardiac action potential

  1. Utilizes 1 ATP for one power stroke and 3 ATP for the restoration
  2. RMP is -50 to -65 mV
  3. Exhibited by fiber tracts & purkinje fibers
  4. Slower rise of the upstroke (phase 0)
  5. a Na+/Ca++ exchanger and Ca++ pump are used to restore ionic concentrations

A. Slow Response Action Potential
B. Fast Response Action Potential

A
  1. B
  2. A
  3. B
  4. A
  5. B
40
Q

Determine the corresponding descriptions of the phases of the fast response action potential

  1. Overwhelmed by the opening of calcium channel, calcium influx counteracted the repolarization caused by the efflux of potassium
  2. Potassium channels remain
    open and will start to close
  3. Once firing level is reached,
    voltage gated sodium channels open and sodium rushes into the cardiac muscle which causes spike potential
  4. Sodium channels will close the inactivation gate to prevent equilibrium
    potential and it is the time to open potassium channels
  5. Goes back to RMP and the sodium potassium pump will cause this

A. Phase 0
B. Phase 1
C. Phase 2
D. Phase 3
E. Phase 4

A
  1. C
  2. D
  3. A
  4. B
  5. E
41
Q

TRUE OR FALSE: Action potential will always precede muscle twitch

A

True

42
Q

A muscle paralyzer acquired from blowfishes that can remove the notch (Phase 1 - peak and initial repolarization)
in the graph, making a fast response AP look like a slow one.

A

Tetrodotoxin

43
Q

RMP of cardiac cells in Fast response action potential

A

-90 mV

44
Q

Also known as pacemaker potential. It is caused by opening of transient calcium channels (that are abundant outside). The channels open and diffusion of calcium ensues, resulting in a graph that goes toward the positive side. This occurs during a slow response action potential.

A

Prepotential

45
Q

During a slow response action potential, long duration calcium channels will close once it is nearing the peak of the graph. This is because of what principle?

A

Principle of Equilibrium Potential

Equilibrium: Same amount of molecules inside and outside. When calcium is nearing its equilibrium potential, the gates of the channel will start to close because when equilibrium occurs, the cell dies

(1) Physiology (16 decks)

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