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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
Time for AP to go from SA to AV node via internodal pathway
.03 seconds 3/100ths of a second
26
Time for AP to go from node to right atrial muscle to depolarize
0.07
27
Time for AP to go from node to left atrial muscle to depolarize
0.09
28
How long is the duration of the P-wave and what is it
0.09 time for all of the atria to depolarize
29
Why does it take longer for AP to reach outside of left atria?
no specialized conduction tissue, has to go through myofibrils
30
Time for a perfectly healthy heart for an AP to go from SA to the entire heart including ventricles?
0.22 seconds
31
Delay at AV node that causes holdup is due to
Delays so the atrials can contract and fill ventricles before AP goes to ventricles and contracts them to eject blood
32
If there are extra action potentials, what can fix that?
The delay of the AV node can help reset. AV node acts as a filter
33
Why is there a delay in AV node? (physically)
fatty and cells don't have many gap junctions, causing AP to take longer to travel.
34
Delay time of AV node
0.12 seconds
35
Delay in bundle of HIS is how long
.01
36
Total time for AP to get from SA node to each of main bundle branches is
0.16 seconds .03 internodal .12 delay in AV node .01 delay in bundle of HIS
37
After an AP from SA node (P-wave), how long will it take QRS to start?
0.16 seconds
38
Where does QRS start?
Main (left and right) bundle branches in the interventricular septum
39
If APs hit AV node while its in complete refractory period, will it generate AP?
no.
40
Direction of electron movement during depolarization of ventricles
toward left foot at 59 degrees on average
41
0 degrees is considered to be
horizontal
42
If the put the electrodes closer to heart, the deflections will appear
much larger.
43
QT interval is measuring
length of time that depolarization happens in ventricular tissue.
44
T-wave is
Ventricles repolarizing
45
P-wave is the
SA node generating AP
46
SA node length and height
positive deflection that is 2 and a half small boxes long and tall
47
If you have an inverted P-wave, that means
the APs are starting outside the SA node
48
If you have a peaked P-wave
Hypertrophy or stretched out right atria more tissue we have, higher magnitude of deflection
49
If you have a long P-wave
Likely an issue with the left atria to be depolarized Left atria stretched out
50
A way to remember peaked and long p-wave issues
Height - Right Long - Left
51
If there is a really big problem with left atria, it can have a
double hump, its an electrical block
52
Q-wave
negative deflection before an R-wave Not all leads will have a Q-wave, depending on orientation.
53
R-wave
Positive deflection that is the depolarization of the ventricles
54
PR interval
Period of time between P-wave and start of R-wave Dont call it PQ cause not everyone has a Q wave
55
PR interval length
0.16 seconds
56
S-wave
neg deflection after R wave
57
How long does it take depolarize last tip of lateral wall of left ventricle?
.06 seconds between bundle branch and lateral wall of left ventricle, ideallyHo
58
How long is QRS?
0.06 seconds. Its the .22 seconds total of heart, minus the .16 (time of nodal tissue and total delays)
59
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?
.18 seconds .39 - .21 = .18 QRS complex
60
Height of QRS
Net deflection of 1.5 mV +1 to upside, bottom side of 0.3 roughly 1.5 mV and 3 large boxes
61
Magnitude of deflection of QRS complex is measured how
how far it goes up above baseline + how far it goes below baseline = total magnitude of deflection
62
If we have a really large QRS complex, it is due to
electrodes really close to heart, or heart tissue is massive (hypertrophy) Hypertrophy would also make it longer
63
What would prolong length but not height of QRS?
dilated cardiomyopathy. Tissue isnt thicker, but it is stretched out and makes it take longer.
64
Where does atria repolarize?
its hidden by large size of QRS, but it looks like it would be right around S-wave
65
At the very end of QRS complex, or end of S-wave, all of the ventricular tissue is
depolarized
66
Reference point for figuring out injury or infarct
J-point or isoelectric point Reference point at end of QRS complex (end of S-wave)
67
After the T-wave, all of the ventricular muscle should be
reset/repolarized. Except the unhealthy tissue.
68
What would area after T-wave look like if there is unhealthy tissue?
Tissue that didnt repolarize and it would show some funky current and generating electrical activity compare it to J-point
69
QT interval what is it and how long is it
time between start of depolarization and time that all the tissue is repolarized .25 - .35 seconds
70
.25 - .35 seconds (QT interval) is the duration of
endocardial fast action potentials
71
ST interval area can show
areas of injury or infarcts not the specific time, but if there is funky currents
72
Why is the T-wave upward deflection
Repolarization in opposite direction of depolarization. Its the repolarization from superficial to deep depolarization is deep to superficial
73
If we needed a faster heart rate, heart will shorten up
ST segment, QT interval, and of course time in between beats Ventricles adjust too by speeding up process of pumping and resetting
74
Lusitropy
Resetting/repolarizing of the ventricle
75
Positive lusitropy
Repolarizes ventricle faster than it normally does
76
negative lusitropy
Repolarizes ventricle slower than it normally does
77
Inotropy
stronger heart beat from more calcium coming into heart/release from SR
78
Chronotropy
Heart rate
79
Dromotropy
Speed of conduction of action potentials
80
What is dromotropy dependent on?
Sodium currents and how much/how fast we have them coming into heart cells
81
RR interval
time in between R waves
82
Typical RR interval is
0.83 seconds
83
60 divided by 0.83 = what is it?
Heart rate. 72bpm
84
What if there RR interval is .91 seconds? .43?
66bpm 140bpm
85
A higher RR interval will result in ________. A lower RR interval will result in _______.
Lower heart rate Higher heart rate
86
Each big box is __ mV
0.5
87
Each small box is ___ mV and ___ seconds
0.1 mV and .04 seconds
88
old school eKG machines fed the paper at how fast?
25mm per second
89
How many big boxes in one second? How many seconds per box?
5 big boxes. 0.2
90
Cardiac refractory period
time after an AP for the heart to reset itself
91
Early premature contraction during refractory period
will result in smaller force of contraction, when it contracts before refractory period is over
92
Where is the relative refractory period?
Very bottom of relative refractory period If AP starts here, it will still generate contraction, just weaker (early premature contraction)
93
A later premature contraction will
still contract the same strength
94
Absolute refractory period
halfway down refractory period, will not elicit much of a contraction, if any at all.

A&P 1 (39 decks)

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