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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
What is the total AV nodal delay before the AP reaches the interventricular septum and bundle branches?
0.13 seconds
25
Where is the Bundle of His located?
Inferior to the AV node and Superior to the Bundle Branches in the Ventricles
26
Where are the Bundle Branches located?
Inferior to the Bundle of His, but Superior to the Interventricular Septum *1st part of the ventricles
26
Where are the SA and AV node located?
R Atria
27
What is the duration of a normal PR interval?
0.16 seconds
28
At about how many seconds does ventricular depolarization begin?
0.16 seconds
29
When does the QRS complex begin?
0.16 seconds
30
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?
Internodal Pathways: R Atria *Anterior *Middle *Posterior
31
What branches off of the Anterior Internodal Pathway?
The Interatrial Bundle [Bachman's Bundle]
32
What is another name for the Interatrial Bundle?
Bachman's Bundle
32
What is the importance of the Interatrial Bundle?
Branches AP from the R atria to the L atria, resulting in propagation of electrical signal to fully depolarize the L atria
32
Per Lecture, what structures are considered in the top of the heart?
SA, AV, Atria's
32
How long does it take to fully depolarize the ventricles at the end of a cardiac AP?
0.22 seconds
33
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?
59 degrees * (+) deflection
33
What is the angle of current of a typical heartbeat?
59 degrees
33
What does a normal EKG represent?
The result of all the AP happening around the heart
34
What is the magnitude of an individual AP in a Ventricular Myocyte?
100 mV
35
If I put electrodes closer to the heart, how would the QRS complex look?
Larger amplitude, as < tissue to go through *Around 3-4 mV high
36
Leads V1-V6, compared to a 3-Lead EKG, register what type of QRS complex?
Larger deflection/more voltage, as closer to the heart and less tissue to go through
37
Why is the Amplitude of the QRS complex in a 3-Lead EKG shorter than leads V1-V6?
Shrunk b/c of air in the lungs and increased tissue/fat to go through
38
Per Lecture, how is the QT interval described in terms of AP?
Length of the Endocardium AP or Full Ventricular Depolarization
39
In an EKG, what is represented by a SA node AP?
The start of the P wave
40
In boxes, how long/tall should a P wave be
2.5 boxes
41
If the P wave originated in the AV node, traveled retrograde to the SA node, what would the EKG look like?
Inverted P wave
41
What heart issue is associated with a longer duration in the P wave?
Conduction problem in the L atria; L atria is more stretched, resulting in longer P wave
41
If I started my AP in the SA node, in what angle direction should I head to reach the AV node?
59 degrees
42
What heart issue is most likely associated with a higher P wave >2.5 boxes?
Problem with the R atria [hypertrophy]; more tissue = more amplitude
43
What could be indicated by a "double" hump in the P Wave
Electrical Block in the L atria
44
How does the Q wave look on the EKG? *Does everyone have a Q wave?
Negative deflection before the R wave *Not everyone has a Q wave, hence why it is a PR interval, not PQ interval
45
What does the S Wave represent in the EKG?
Negative deflection after the R wave
46
How long is a typical QRS complex?
0.06 seconds
47
What 2 things can indicate a larger deflection in the QRS complex?
Increased ventricular tissue or the electrodes are placed closer to the heart
48
What disease process can prolong the QRS without increasing the amplitude?
Dilated Cardiomyopathy
49
What does the R wave represent in the EKG?
Beginning of ventricular depolarization
50
When does the QRS complex End?
When all of the ventricular muscle mass has been depolarized
51
Around what part of the EKG represents Atrial Repolarization? *Why can't you see it?
Around the S-Wave *Overshadowed by Ventricular Depolarization
52
Why is the end of the S-Wave important? *What are 2 names for this spot
Point where we can determine current of injury *J-Point or Isoelectric Point
53
Why is the end of the T-Wave important?
All healthy ventricular tissue will be repolarized, but unhealthy tissue will be still depolarized
53
What is the QT interval? *Duration?
Start of Interventricular Septum depolarization to end of ventricles depolarizing *0.25-0.35 seconds
54
What does a faster HR do to the ST-segment? *QT interval?
Shorts ST segment/QT interval, which makes the ventricle repolarize faster than normal, leading to a firing of an AP Faster
55
What is the RR interval? *Formula?
Time between adjacent QRS complexes *60 sec/ 0.83 [RR] = 72 BPM
55
In terms of Heart Tissue AP, how can we describe the QT interval?
Endocardial Fast AP duration
55
What is Chronotropy?
Heart Rate
55
What is Inotropy?
Stronger contraction via more Ca++ coming in from the SR
56
What is Dromotropy?
Speed of conduction of electrical impulses
56
What is Lusitropy? *+ agent *- agent
Resetting of the ventricle *+ = repolarize the ventricle faster than normal = increased HR * - = repolarize the ventricle slower than normal = decreased HR
57
What is dromotropy dependent on?
Entirely dependent of Na+ currents and how much ionic Na+ flow we have
58
Y Axis Big Box
0.5 mV
59
Y Axis Small Box
0.1 mV
59
Big Box Time
0.2 sec
60
Small Box Time
0.04 sec
61
What was the units on the Paper EKG fed thru the machine?
25 mm/sec
62
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?
+ deflection
63
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?
- deflection
64
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?
+ deflection; T Wave
65
Describe a Fast Ventricular Myocyte AP Phase 4 slope *Can it fire an AP on its' own?
Shallow slope from leaky Na+ channels *Can fire AP on own if given enough time
66
Another name for P4 in the SA Node Slow AP
Diastolic Depolarization
67
Why is Phase 0 in a SA nodal cell slower than Phase 0 in a ventricular myocyte?
L-Type Ca++ channels are slower to open and slower to close [longer AP duration]
68
If the heart has a steep Phase 0, what happens? *Why
Faster AP spread thru the heart b/c increased Ca++ leads to increased Na+ spreading throughout the ventricular muscle
69
If you have a shallow Phase 0, what happens?
Slower AP spread throughout the heart
70
What happens in Phase 3 of a SA nodal myocyte?
K channels opening and slow Ca++ channels closing
71
What Phases do a SA nodal cell have?
Phase 4, 0, 3 [maybe 2]
72
Why is the AV node Vrm more negative than SA node?
Less leaky to Na+ and Ca++ than the SA node; longer time to reach threshold
73
Where are HCN channels located?
Mostly SA node Some AV node Sparse in Ventricular Myocytes
74
Where are the deeper, longer AP most likely found?
Subendocardium
75
Would an Epicardial AP be deeper/longer than a subendocardium?
Epicardium repolarizes before the endocardial tissue, so starts a little later, so no
76
Describe an Atrial AP
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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