Chapter 2 - Conduction System

Question 0

Pacemaker Cells

Answer 0

Specialized cells responsible for the generation & conduction of electrical impulses. (located in the nodes, bundles, bundle branches, & branching networks)

Question 1

Myocardial Cells

Answer 1

The working/mechanical cells of the heart. Contraction & relaxation are the primary functions.

Question 2

Automaticity

Answer 2

Ability of certain cells to initiate electrical impulses without external stimulation. (pacemaker cells of SA node - greatest frequency; cells in AV node & purkinje fibers initiate impulse when SA node fails)

Question 3

Excitability

Answer 3

Characteristic shared by all cardiac cells to acknowledge & respond to an electrical impulse.

Question 4

Contractility

Answer 4

Ability of cardiac cells to shorten & cause cardiac muscle contraction in response to an electrical stimulus. (coordination of cardiac muscle cells to produce a regular heartbeat)

Question 5

Conductivity

Answer 5

Ability of cardiac cells to receive an electrical stimulus & then transmit it to other cardiac cells.

Question 6

Depolarization

Answer 6

Electrical occurrence resulting in myocardial contraction. (endocardium –> epicardium)

Question 7

Repolarization

Answer 7

Results in muscle relaxation. (epicardium –> endocardium)

Question 8

Polarization

Answer 8

Resting state of cardiac cell. (inside is electrically negative relative to the outside of the cell)

Question 9

Sinoatrial Node (SA Node)

Answer 9

Primary pacemaker of the heart.
[Function] - initiates impulses
[Location] - upper right atrial wall, near opening of superior vena cava
[Pace] 60-100 bpm

Question 10

Internodal Tracts

Answer 10

[Function] transmits impulse from SA node –> AV node

[Location] wall of right atrium

Question 11

AV Node (atrioventricular node)

Answer 11

[Function] delays connection
[Location] behind tricuspid valve
[Pace] 40-60 bpm

Question 12

Bundle of His

Answer 12

[Function] connection between atria & ventricles

[Location] upper portion of interventricular septum

Question 13

Bundle Branches (left & right)

Answer 13

[Function] spreads impulse throughout ventricles

[Location] left ventricle & right ventricle

Question 14

Purkinje Fibers

Answer 14

[Function] carries impulses to muscles in ventricles
[Location] muscular layer of ventricles
[Pace] 20-40 bpm

Question 15

What is the electrical pathway of the Conduction System?

Answer 15

SA node (60-100 bpm) –> through atria to AV node (via internodal tracts) = atrial depolarization –> impulse continues into the Bundle of His, down the Left & Right Bundle Branches –> Purkinje fibers = ventricular depolarization.