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Block 3 physiology > Cardiac Conduction > Flashcards

Cardiac Conduction Flashcards

(52 cards)

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1
Q

Where does cardiac contraction originate?

A

specialized cardiac pacemakers

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2
Q

Where does the cardiac contraction spread through?

A

through myocardium via myocardial conduction system

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3
Q

What is the SA node also called?

A

pacemaker

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4
Q

SA node: bpm

A

60-100 bpm

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5
Q

flow of cardiac contraction

A
  • SA node
  • Internodal atrial pathways
  • AV node
  • Bundle of His
  • Purkinje system
  • Intrinsic ventricular rate
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6
Q

AV node: bpm

A

40-60 bpm

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7
Q

intrinsic ventricular rate: bpm

A

<40 bpm

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8
Q

what happens after the pacemakers discharge?

A

the membrane potential returns to resting potential prior to discharging again

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9
Q

The ______ pacemaker conducting to the ventricles always sets the ventricular rate!

A

The fastest pacemaker conducting to the ventricles always sets the ventricular rate!

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10
Q

normal pacemaker sequence of rates

A

SA>AV>ventricular

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11
Q

areas of the heart which may serve as potential pacemakers

A

automaticity foci

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12
Q

_____ _______ determined by where pacing originates

A

Heart rhythm determined by where pacing originates

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13
Q

_______ foci of automaticity (originating outside of SA or AV nodes) can result in _________

A

Ectopic foci of automaticity (originating outside of SA or AV nodes) can result in arrhythmia

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14
Q

SA node origin = _____ rhythm

A

SA node origin = sinus rhythm

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15
Q

AV node origin = ____ rhythm

A

AV node origin = junctional rhythm

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16
Q

ventricle node origin = ____ rhythm

A

ventricle node origin = ventricular rhythm

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17
Q

Which nerves arise from spinal T2-4 segments?

A

postganglionic sympathetic nerves

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18
Q

What is the neurotransmitter for postganglionic sympathetic nerves?

A

norepinephrine

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19
Q

Where do the postganglionic nerves pass?

A

into the cardiac plexus to the SA node (right) and AV node (left)

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20
Q

What is in response to SNS stimulation?

A

adrenal epinephrine

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21
Q

effects of the Sympathetic NS

Study These Flashcards
A
  • Increase SA node pacing
  • Increased AV node transmission
  • Increase myocardial contractility
22
Q

What nerve provides parasympathetic control?

23
Q

What is the neurotransmitter for the vagus nerve?

Study These Flashcards
A

acetylcholine

24
Q

effect of the Parasympathetic NS

Study These Flashcards
A
  • decreased SA node pacing

- delayed signal transmission through AV node

25
That does delayed signal transmission through the AV node cause?
increased refractory period
26
speeds depolarization and increases discharge rate and force of contraction
norepinephrine stimulation in SNS
27
hyperpolarizes and decreases rate of firing (no effect on contractility)
Ach stimulation in PNS
28
_________ firing rate is also influenced by _____________ and _____.
Pacemaker firing rate is also influenced by temperature and drugs.
29
What drug inhibits the PNS? Stimulates PNS?
- atropine inhibits | - digitalis stimulates
30
Which node normal sets the pace?
SA node
31
AV node _____ transmission to bundle of _____
AV node SLOWS transmission to bundle of His
32
What does slowing transmission to bundle of His do?
coordinates atrial and ventricular firing
33
What wave is generated by activation of both atria?
P wave
34
The interventricular ______ is activated first, from ____ to right, generating the __-wave
The interventricular septum is activated first, from left to right, generating the Q-wave
35
What generates the R wave?
left and right ventricular wall activation
36
What generates the S wave?
A few small areas of the ventricles are activated at a late stage
37
What generates the T wave?
ventricular repolarization
38
size of wave deflection that is either positive or negative
voltage
39
Where is voltage greater?
in areas where there is more CONDUCTING muscle
40
Is voltage greater in the ventricles or atria?
ventricles
41
Is voltage greater in the right ventricles or left ventricle?
left ventricle
42
Is voltage greater in areas of hypertrophy or normal mass of cardiac tissue?
areas of hypertrophy
43
Does ischemic or dead tissue conduct voltage?
NO
44
average direction of the combined electrical activity within the ventricles, affected by tissue mass, tissue conductivity
frontal axis/QRS axis
45
causes of left axis deviation
- Left ventricular hypertrophy - Left bundle branch block (LBBB) - Left anterior fasicular block (LAHB) - High diaphragm (ascites, pregnancy, abdominal mass) - Normal variants (especially elderly, obese) - Wolf-Parkinson-White syndrome (WPW)
46
LVH - ___% of cases present with LAD
LVH - 50% of cases present with LAD
47
Causes of right axis deviation
- Right ventricular hypertrophy - Right bundle branch block (RBBB) - Left posterior fascicular block (LPHB) - Flat diaphragm (COPD) - Normal variants (especially young, thin)
48
RVH - ____% cases present with RAD
RVH - 100% cases present with RAD
49
indicated by the equiphasic precordial lead being either V3 or V4
normal horizontal axis
50
indicated if equiphasic lead is V1 or V2
right axis rotation
51
indicated if equiphasic lead is V5 or V6
left axis rotation
52
Axis deviation (_____ plane) and rotation (_______ plane) is always ____ from infarction and ______ hypertrophy
Axis deviation (vertical plane) and rotation (horizontal plane) is always away from infarction and towards hypertrophy

Block 3 physiology (6 decks)

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