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A&P 1 > Exam 4 Lecture 3 > Flashcards

Exam 4 Lecture 3 Flashcards

1
Q

What is the Cardiac Refractory Period?

A

Stimulating an AP before the heart can fully reset

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2
Q

What is the Relative Refractory Period?
*What happens to the AP and heart pumping?

A

Reset for the most part, but not fully
*Weaker AP and Pumping

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3
Q

What is the Early Premature Contraction Period

A

Smaller than normal AP and weaker pumping

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4
Q

What is the Later Premature Contraction Period
*Describe the AP

A

Heart has completely reset itself, but still has an early AP
*Strongest AP out of the refractory issues

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5
Q

What is the Absolute Refractory period
*Describe the AP

A

Stimulation during an active AP
*Either no AP or very minimal

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6
Q

What is the rate of Action Potentials Per second in the heart?

A

0.83 AP/sec

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7
Q

Normal HR, including AP per second formula

A

60 seconds / 0.83 AP = 72 BPM

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8
Q

What is the HR in the SA Node, if it did not include the Vagus Nerves or SNS chain?

A

110 b/min

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9
Q

What is the HR in the SA Node, if it did not include the SNS chain?

A

60-62 BPM

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10
Q

What is the HR in the SA Node, if it did not include the Vagus Nerves, but included the SNS chain?

A

120 BPM

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11
Q

How many beats does the SNS chain add by itself?

A

10 BPM

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12
Q

Where in the heart is the origin of pacing?

A

SA Node

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13
Q

What is the conduction system of the heart?

A

Purkinje Fibers

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13
Q

If the AV Node became the PM of the heart, what would the HR be?

A

40-60 BPM

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14
Q

If you only had Purkinje Fibers as the PM of the heart, what would be the HR?

A

15-30 BPM

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15
Q

Which part of the EKG illustrates Atrial Depolarization?

A

P-Wave
*(+) deflection

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16
Q

What is the duration of a normal P Wave?

A

0.09 seconds

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17
Q

How long does it take for an action potential to reach the AV node from the SA node?

A

0.03 seconds

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18
Q

How long does it take to fully depolarize the R atria?

A

0.07 seconds

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19
Q

How long does it take to fully depolarize the L atria?

A

0.09 seconds

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20
Q

Name 2 Functions that the AV node performs?

A

*Prevents ventricles fully contracting before being filled up with blood by the Atria
*Acts as a filter to keep stray AP in the atria and not allowing them to generate down to the ventricles

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21
Q

Why is there a delay in AP in the AV node?

A

*Main - Not many gap junctions
*2nd - very fat, so poor conductor of electricity

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22
Q

How long is the AV node delay, without the bundle of his?

A

0.12 sec

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23
Q

How long is the delay in the bundle of his?

A

0.01 seconds

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24
Q

What is the total AV nodal delay before the AP reaches the interventricular septum and bundle branches?

A

0.13 seconds

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25
Q

Where is the Bundle of His located?

A

Inferior to the AV node and Superior to the Bundle Branches in the Ventricles

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26
Q

Where are the Bundle Branches located?

A

Inferior to the Bundle of His, but Superior to the Interventricular Septum
*1st part of the ventricles

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26
Q

Where are the SA and AV node located?

A

R Atria

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27
Q

What is the duration of a normal PR interval?

A

0.16 seconds

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28
Q

At about how many seconds does ventricular depolarization begin?

A

0.16 seconds

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29
Q

When does the QRS complex begin?

A

0.16 seconds

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30
Q

What are the 3 connecting parts of the SA to the AV node called?
*Name all 3 Parts
*Where are these located in the heart?

A

Internodal Pathways: R Atria
*Anterior
*Middle
*Posterior

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31
Q

What branches off of the Anterior Internodal Pathway?

A

The Interatrial Bundle [Bachman’s Bundle]

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32
Q

What is another name for the Interatrial Bundle?

A

Bachman’s Bundle

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32
Q

What is the importance of the Interatrial Bundle?

A

Branches AP from the R atria to the L atria, resulting in propagation of electrical signal to fully depolarize the L atria

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32
Q

Per Lecture, what structures are considered in the top of the heart?

A

SA, AV, Atria’s

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32
Q

How long does it take to fully depolarize the ventricles at the end of a cardiac AP?

A

0.22 seconds

33
Q

If you place a lead on the R shoulder (-) and L foot (+), what is the angle of current?
* What kind of deflection is this depolarization?

A

59 degrees
* (+) deflection

33
Q

What is the angle of current of a typical heartbeat?

A

59 degrees

33
Q

What does a normal EKG represent?

A

The result of all the AP happening around the heart

34
Q

What is the magnitude of an individual AP in a Ventricular Myocyte?

A

100 mV

35
Q

If I put electrodes closer to the heart, how would the QRS complex look?

A

Larger amplitude, as < tissue to go through
*Around 3-4 mV high

36
Q

Leads V1-V6, compared to a 3-Lead EKG, register what type of QRS complex?

A

Larger deflection/more voltage, as closer to the heart and less tissue to go through

37
Q

Why is the Amplitude of the QRS complex in a 3-Lead EKG shorter than leads V1-V6?

A

Shrunk b/c of air in the lungs and increased tissue/fat to go through

38
Q

Per Lecture, how is the QT interval described in terms of AP?

A

Length of the Endocardium AP or Full Ventricular Depolarization

39
Q

In an EKG, what is represented by a SA node AP?

A

The start of the P wave

40
Q

In boxes, how long/tall should a P wave be

A

2.5 boxes

41
Q

If the P wave originated in the AV node, traveled retrograde to the SA node, what would the EKG look like?

A

Inverted P wave

41
Q

What heart issue is associated with a longer duration in the P wave?

A

Conduction problem in the L atria; L atria is more stretched, resulting in longer P wave

41
Q

If I started my AP in the SA node, in what angle direction should I head to reach the AV node?

A

59 degrees

42
Q

What heart issue is most likely associated with a higher P wave >2.5 boxes?

A

Problem with the R atria [hypertrophy]; more tissue = more amplitude

43
Q

What could be indicated by a “double” hump in the P Wave

A

Electrical Block in the L atria

44
Q

How does the Q wave look on the EKG?
*Does everyone have a Q wave?

A

Negative deflection before the R wave
*Not everyone has a Q wave, hence why it is a PR interval, not PQ interval

45
Q

What does the S Wave represent in the EKG?

A

Negative deflection after the R wave

46
Q

How long is a typical QRS complex?

A

0.06 seconds

47
Q

What 2 things can indicate a larger deflection in the QRS complex?

A

Increased ventricular tissue or the electrodes are placed closer to the heart

48
Q

What disease process can prolong the QRS without increasing the amplitude?

A

Dilated Cardiomyopathy

49
Q

What does the R wave represent in the EKG?

A

Beginning of ventricular depolarization

50
Q

When does the QRS complex End?

A

When all of the ventricular muscle mass has been depolarized

51
Q

Around what part of the EKG represents Atrial Repolarization?
*Why can’t you see it?

A

Around the S-Wave
*Overshadowed by Ventricular Depolarization

52
Q

Why is the end of the S-Wave important?
*What are 2 names for this spot

A

Point where we can determine current of injury
*J-Point or Isoelectric Point

53
Q

Why is the end of the T-Wave important?

A

All healthy ventricular tissue will be repolarized, but unhealthy tissue will be still depolarized

53
Q

What is the QT interval?
*Duration?

A

Start of Interventricular Septum depolarization to end of ventricles depolarizing
*0.25-0.35 seconds

54
Q

What does a faster HR do to the ST-segment?
*QT interval?

A

Shorts ST segment/QT interval, which makes the ventricle repolarize faster than normal, leading to a firing of an AP Faster

55
Q

What is the RR interval?
*Formula?

A

Time between adjacent QRS complexes
*60 sec/ 0.83 [RR] = 72 BPM

55
Q

In terms of Heart Tissue AP, how can we describe the QT interval?

A

Endocardial Fast AP duration

55
Q

What is Chronotropy?

A

Heart Rate

55
Q

What is Inotropy?

A

Stronger contraction via more Ca++ coming in from the SR

56
Q

What is Dromotropy?

A

Speed of conduction of electrical impulses

56
Q

What is Lusitropy?
*+ agent
*- agent

A

Resetting of the ventricle
*+ = repolarize the ventricle faster than normal = increased HR
* - = repolarize the ventricle slower than normal = decreased HR

57
Q

What is dromotropy dependent on?

A

Entirely dependent of Na+ currents and how much ionic Na+ flow we have

58
Q

Y Axis Big Box

A

0.5 mV

59
Q

Y Axis Small Box

A

0.1 mV

59
Q

Big Box Time

A

0.2 sec

60
Q

Small Box Time

A

0.04 sec

61
Q

What was the units on the Paper EKG fed thru the machine?

A

25 mm/sec

62
Q

If I have + electrode in the L arm and a - electrode in the R shoulder, what deflection would depolarization be from R shoulder to L arm?

A

+ deflection

63
Q

If I have + electrode in the L arm and a - electrode in the R shoulder, what deflection would repolarization be from R shoulder to L arm?

A
  • deflection
64
Q

If I have + electrode in the L arm and a - electrode in the R shoulder, what deflection would repolarization be from L arm to R shoulder?

A

+ deflection; T Wave

65
Q

Describe a Fast Ventricular Myocyte AP Phase 4 slope
*Can it fire an AP on its’ own?

A

Shallow slope from leaky Na+ channels
*Can fire AP on own if given enough time

66
Q

Another name for P4 in the SA Node Slow AP

A

Diastolic Depolarization

67
Q

Why is Phase 0 in a SA nodal cell slower than Phase 0 in a ventricular myocyte?

A

L-Type Ca++ channels are slower to open and slower to close [longer AP duration]

68
Q

If the heart has a steep Phase 0, what happens?
*Why

A

Faster AP spread thru the heart b/c increased Ca++ leads to increased Na+ spreading throughout the ventricular muscle

69
Q

If you have a shallow Phase 0, what happens?

A

Slower AP spread throughout the heart

70
Q

What happens in Phase 3 of a SA nodal myocyte?

A

K channels opening and slow Ca++ channels closing

71
Q

What Phases do a SA nodal cell have?

A

Phase 4, 0, 3 [maybe 2]

72
Q

Why is the AV node Vrm more negative than SA node?

A

Less leaky to Na+ and Ca++ than the SA node; longer time to reach threshold

73
Q

Where are HCN channels located?

A

Mostly SA node
Some AV node
Sparse in Ventricular Myocytes

74
Q

Where are the deeper, longer AP most likely found?

A

Subendocardium

75
Q

Would an Epicardial AP be deeper/longer than a subendocardium?

A

Epicardium repolarizes before the endocardial tissue, so starts a little later, so no

76
Q

Describe an Atrial AP

A

Mix between fast and slow
*only contract short period of time and dont have high resistance to push against

A&P 1 (24 decks)

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