Intrinsic Conduction System Flashcards


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1

Describe the path of "electrical" signals through the intrinsic conduction system

SA node > AV node > Bundle of His > Left and right bundle branches > Purkinje Fibers

2

T/F: The "electricity" of the heart is created by electron flow.

False

3

What are the contractions of the heart initiated by?

Ion currents

4

Where in the intrinsic pathway does the signal pause?

AV node

5

Why does the signal pause at the AV node?

To allow the ventricles to fill

6

AP in the heart is spread by ______________. This is possible because of special low-resistance gap jxns

Cell-to-cell conduction

7

Cell-to-cell conduction in the heart results in___________________

Functional syncytium

8

Where is the SA node found?

RA (right of SVC orifice)

9

T/F: The SA node is enriched only with Sympatheic nerve fibers

False

10

The SA node sets the heart rate. This is known as ________________

Sinus rhythm

11

What is the size of the SA node?

~1.5 cm long and 2-3 mm wide

12

Where is the AV node located?

Beneath the endocardium in the inferoposterior region of the interarterial septum

13

Which node is the "gateway" into the ventricles

AV node

14

The SA node is connected to the AV node by how many pathways?

3

15

What class of drug slows the AV conduction pathway?

Beta-blockers

16

Which part of the intrinsic pathway has the fastest conduction velocity?

Purkinje Fibers

17

Which part of the intrinsic pathway has the slowest conduction velocity?

SA node

18

Which part of the intrinsic pathway has the fastest pacemaker rate?

SA node

19

List extrinsic factors that would increase conduction velocity

  • Sympathetic stimulation
  • M antagonists
  • Beta agonist
  • Circulating catecholamines
  • Hyperthyroidism
20

List extrinsic factors that would decrease conduction velocity

  • Parasympatheitic stimulation
  • M agonists
  • Beta blockers
  • Ischemia/hypoxia
  • Na and Ca blockers
21

What are the primary factors involved with abnormal impulse formation?

  • Altered automaticity
  • Abnormal automaticity w/in atria/ventricles
  • Triggered activity
22

Occurs when a conducting pathway is prematurely stimulated via a previously conducted AP

Reentry

23

Impulses are transmitted back into the atria. If this persists, tachycardia may be generated

Retrograde conduction

24

T/F: Reentry arrhythmias may be paroxysmal due to the ANS

True

25

What drugs are used to prevent and/or eliminate reentry?

Antiarrhythmic drugs

26

Where can local reentry sites be located?

Atria or ventricles

27

Describe an example of global reentry

Pathway via the bundle of Kent that flows into the RV w/o going through the AV node. Impulse is transmitted to LV and then in a retrograde motion returns to the atria via the AV node

28

What is happening in the heart in Wolff-Parkinson-White Syndrome?

Global and local reentry is causing depolarization to occur earlier than normal

29

Which wave corresponds with atrial contraction?

P wave

30

T/F: The p wave preceeds the mechanical contraction

True

31

Which part of the ECG is the signal for the ventricles to contract?

QRS complex

32

A wave of depolarization moving toward a positive electrode is defined as:

Positive deflection in the ECG

33

A wave of depolarization moving toward a negative electrode is defined as:

Negative deflection in the ECG

34

A wave of depolarization moving perpendicular to a positive/negative electrode is defined as:

No overall deflection in the ECG

35

T/F: The voltage amplitude of an ECG is indirectly related to the mass of the tissue experiencing either depolarization/repolarization

False

36

T/F: The instantaneous amplitudes in the ECG trace are a function of the orientation of the positive electrode relative to the mean electrical vector in the ECG

True

37

Define normal sinus rhythm

SA node is leading pace

38

Define bradycardia

Slowed HR (<60 BPM)

39

Define tachycardia

Fast HR (>100 BPM)

40

Happens when ventricles beat at a very fast rate

Ventricular tachycardia

41

Aka "Rhythm of Death"

Ventricular fibrillation

42

Sudden blow to the chest during this phase in the cardiac cycle can lead to ventricular fibrillation and death.

Commotio cordis

43

Summation of the individual instantaneous electrical vectors of depolarization at a given instant of time

Mean electrical vector