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A&P 1 > Exam 4 - Lecture 3 > Flashcards

Exam 4 - Lecture 3 Flashcards

1
Q

Anything that sends electrons towards a positive electrode will

A

Give a positive reading/positive deflection

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2
Q

If we have depolarization in one direction causing a negative deflection, repolarization in the same direction would cause

A

Positive deflection

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3
Q

If we have depolarization in one direction causing a negative deflection, repolarization in the same direction would cause

A

Positive deflection

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4
Q

Phase 4 of ventricle muscle is very ____

A

Slightly sloped.

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5
Q

Phase 4 of SA node is also called

A

Diastolic depolarization or phase 4 depolarization

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6
Q

Phase 0 of SA node

A

Upward stroke up action potential, not as sloped as most AP.

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7
Q

In the nodal areas, phase 0 is ______ channels.

A

Slow L-type Ca++ channels.

Slower to open, slower to close.

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8
Q

Duration/slope of phase 0 is very important because

A

Determines how fast the action potentials travel throughout the heart.

If it’s super fast, everything else is super fast from sodium traveling through gap junctions

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9
Q

Phase 3 of nodal areas

A

L-type closing, VG-K re-opening to set the cell

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10
Q

Definite phases of nodal areas

A

4, 0 and 3.

Some textbooks will say there is a 2nd phase.

There is not a 1st phase at all.

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11
Q

AV node VRm and slope and threshold compared to SA node , and why?

A

Not as leaky to sodium and calcium in phase 4.

VRm is more negative than SA node, and less slope.

Thats why it’s slower if it’s the pacemaker.

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12
Q

HCN channels in the heart are found where?

A

Most in the SA

A lot but less in AV

Ventricles there’s hardly any, but they are there.

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13
Q

Real deep interior ventricular APs are

A

Pretty long, longer plateau phase

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14
Q

Repolarization is set quicker for epicardium than

A

Subendocardium

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15
Q

Are atrials pumping against high or low resistance?

A

Low

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16
Q

Atria APs are compared as

A

In between a fast and slow AP

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17
Q

SA node HR and how often does it generate an AP?

A

72 bpm; every 0.83 seconds

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18
Q

If we took all of the nervous influences away from SA node, it would generate a heart rate of ____.

If we add SNS activity ONLY:

A

110 bpm; 120bpm (up by 10bpm)

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19
Q

What has a greater affect on HR, SNS or PNS (vagal)

A

PNS is much stronger effect

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20
Q

Secondary pacemaker is ___ and it generates spontaneous APs at __________ per minute.

A

AV node; 40-60bpm

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21
Q

Other pacemaker system of heart not SA or AV node, and it will spontaneously generate APs at ____ per minute.

A

purkinje fibers which is conduction system of ventricles, and it will beat at 15-30bpm.

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22
Q

What is the conduction system of the heart specifically for other than the obvious generating APs for heart beat?

A

Coordinated timing of all of the muscle mass. Needs to be an orderly process for the signals that each take a defined amount of time.

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23
Q

Conduction system in right atria are called

A

3 internodal pathways (in between SA and AV node)
Anterior
middle
posterior

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24
Q

Anterior internodal pathway is and its also called?

A

a bundle or collection of tissue that will conduct signals to left atrial pathway

Interatria bundle or bachman’s bundle

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25
Q

Time for AP to go from SA to AV node via internodal pathway

A

.03 seconds

3/100ths of a second

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26
Q

Time for AP to go from node to right atrial muscle to depolarize

A

0.07

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27
Q

Time for AP to go from node to left atrial muscle to depolarize

A

0.09

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28
Q

How long is the duration of the P-wave and what is it

A

0.09

time for all of the atria to depolarize

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29
Q

Why does it take longer for AP to reach outside of left atria?

A

no specialized conduction tissue, has to go through myofibrils

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30
Q

Time for a perfectly healthy heart for an AP to go from SA to the entire heart including ventricles?

A

0.22 seconds

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31
Q

Delay at AV node that causes holdup is due to

A

Delays so the atrials can contract and fill ventricles before AP goes to ventricles and contracts them to eject blood

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32
Q

If there are extra action potentials, what can fix that?

A

The delay of the AV node can help reset.

AV node acts as a filter

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33
Q

Why is there a delay in AV node? (physically)

A

fatty and cells don’t have many gap junctions, causing AP to take longer to travel.

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34
Q

Delay time of AV node

A

0.12 seconds

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35
Q

Delay in bundle of HIS is how long

A

.01

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36
Q

Total time for AP to get from SA node to each of main bundle branches is

A

0.16 seconds

.03 internodal

.12 delay in AV node
.01 delay in bundle of HIS

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37
Q

After an AP from SA node (P-wave), how long will it take QRS to start?

A

0.16 seconds

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38
Q

Where does QRS start?

A

Main (left and right) bundle branches in the interventricular septum

39
Q

If APs hit AV node while its in complete refractory period, will it generate AP?

A

no.

40
Q

Direction of electron movement during depolarization of ventricles

A

toward left foot at 59 degrees on average

41
Q

0 degrees is considered to be

A

horizontal

42
Q

If the put the electrodes closer to heart, the deflections will appear

A

much larger.

43
Q

QT interval is measuring

A

length of time that depolarization happens in ventricular tissue.

44
Q

T-wave is

A

Ventricles repolarizing

45
Q

P-wave is the

A

SA node generating AP

46
Q

SA node length and height

A

positive deflection that is 2 and a half small boxes long and tall

47
Q

If you have an inverted P-wave, that means

A

the APs are starting outside the SA node

48
Q

If you have a peaked P-wave

A

Hypertrophy or stretched out right atria

more tissue we have, higher magnitude of deflection

49
Q

If you have a long P-wave

A

Likely an issue with the left atria to be depolarized

Left atria stretched out

50
Q

A way to remember peaked and long p-wave issues

A

Height - Right
Long - Left

51
Q

If there is a really big problem with left atria, it can have a

A

double hump, its an electrical block

52
Q

Q-wave

A

negative deflection before an R-wave

Not all leads will have a Q-wave, depending on orientation.

53
Q

R-wave

A

Positive deflection that is the depolarization of the ventricles

54
Q

PR interval

A

Period of time between P-wave and start of R-wave

Dont call it PQ cause not everyone has a Q wave

55
Q

PR interval length

A

0.16 seconds

56
Q

S-wave

A

neg deflection after R wave

57
Q

How long does it take depolarize last tip of lateral wall of left ventricle?

A

.06 seconds between bundle branch and lateral wall of left ventricle, ideallyHo

58
Q

How long is QRS?

A

0.06 seconds.

Its the .22 seconds total of heart, minus the .16 (time of nodal tissue and total delays)

59
Q

If the Lateral wall of left ventricle shows .39 seconds to depolarize, and the SA/AV node takes .21 seconds to depolarize + the delay, how long did it take the ventricles to depolarize? What would this be on the EKG?

A

.18 seconds

.39 - .21 = .18

QRS complex

60
Q

Height of QRS

A

Net deflection of 1.5 mV

+1 to upside, bottom side of 0.3

roughly 1.5 mV and 3 large boxes

61
Q

Magnitude of deflection of QRS complex is measured how

A

how far it goes up above baseline + how far it goes below baseline = total magnitude of deflection

62
Q

If we have a really large QRS complex, it is due to

A

electrodes really close to heart, or heart tissue is massive (hypertrophy)

Hypertrophy would also make it longer

63
Q

What would prolong length but not height of QRS?

A

dilated cardiomyopathy.

Tissue isnt thicker, but it is stretched out and makes it take longer.

64
Q

Where does atria repolarize?

A

its hidden by large size of QRS, but it looks like it would be right around S-wave

65
Q

At the very end of QRS complex, or end of S-wave, all of the ventricular tissue is

A

depolarized

66
Q

Reference point for figuring out injury or infarct

A

J-point or isoelectric point

Reference point at end of QRS complex (end of S-wave)

67
Q

After the T-wave, all of the ventricular muscle should be

A

reset/repolarized. Except the unhealthy tissue.

68
Q

What would area after T-wave look like if there is unhealthy tissue?

A

Tissue that didnt repolarize and it would show some funky current and generating electrical activity

compare it to J-point

69
Q

QT interval what is it and how long is it

A

time between start of depolarization and time that all the tissue is repolarized

.25 - .35 seconds

70
Q

.25 - .35 seconds (QT interval) is the duration of

A

endocardial fast action potentials

71
Q

ST interval area can show

A

areas of injury or infarcts

not the specific time, but if there is funky currents

72
Q

Why is the T-wave upward deflection

A

Repolarization in opposite direction of depolarization.

Its the repolarization from superficial to deep

depolarization is deep to superficial

73
Q

If we needed a faster heart rate, heart will shorten up

A

ST segment, QT interval, and of course time in between beats

Ventricles adjust too by speeding up process of pumping and resetting

74
Q

Lusitropy

A

Resetting/repolarizing of the ventricle

75
Q

Positive lusitropy

A

Repolarizes ventricle faster than it normally does

76
Q

negative lusitropy

A

Repolarizes ventricle slower than it normally does

77
Q

Inotropy

A

stronger heart beat from more calcium coming into heart/release from SR

78
Q

Chronotropy

A

Heart rate

79
Q

Dromotropy

A

Speed of conduction of action potentials

80
Q

What is dromotropy dependent on?

A

Sodium currents and how much/how fast we have them coming into heart cells

81
Q

RR interval

A

time in between R waves

82
Q

Typical RR interval is

A

0.83 seconds

83
Q

60 divided by 0.83 = what is it?

A

Heart rate.

72bpm

84
Q

What if there RR interval is .91 seconds?

.43?

A

66bpm

140bpm

85
Q

A higher RR interval will result in ________.

A lower RR interval will result in _______.

A

Lower heart rate

Higher heart rate

86
Q

Each big box is __ mV

A

0.5

87
Q

Each small box is ___ mV and ___ seconds

A

0.1 mV and .04 seconds

88
Q

old school eKG machines fed the paper at how fast?

A

25mm per second

89
Q

How many big boxes in one second? How many seconds per box?

A

5 big boxes.

0.2

90
Q

Cardiac refractory period

A

time after an AP for the heart to reset itself

91
Q

Early premature contraction during refractory period

A

will result in smaller force of contraction, when it contracts before refractory period is over

92
Q

Where is the relative refractory period?

A

Very bottom of relative refractory period

If AP starts here, it will still generate contraction, just weaker (early premature contraction)

93
Q

A later premature contraction will

A

still contract the same strength

94
Q

Absolute refractory period

A

halfway down refractory period, will not elicit much of a contraction, if any at all.

A&P 1 (39 decks)

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