19.3 Cardiac Muscle and the Cardiac Conduction System

Question 1

myogenic

Answer 1

having a signal that originates within the heart itself

Question 2

autorhythmic

Answer 2

dependent on itself rather than on the nervous system for its rhythm

Question 3

cardiomyocytes

Answer 3

the muscle cells of the heart

Question 4

intercalated disc

Answer 4

A complex of fascia adherens, gap junctions, and desmosomes that join two cardiac muscle cells end to end, microscopically visible as a dark line that helps to histologically distinguish this muscle type; functions as a mechanical and electrical link between cells.

Question 5

cardiac conduction system

Answer 5

the system that coordinates the heartbeat, composed of an internal pacemaker and nervelike conduction pathways through the myocardium

Question 6

sinuatrial (SA) node

Answer 6

The pacemaker of the heart; a patch of autorhythmic cells in the right atrium that initiates each heartbeat.

Question 7

atrioventricular (AV) node

Answer 7

A group of autorhythmic cells in the interatrial septum of the heart that relays excitation from the atria to the ventricles.

Question 8

atrioventricular (AV) bundle

Answer 8

the pathway by which signals leave the AV node

Question 9

subendocardial conducting network (formerly, Purkinje fibers)

Answer 9

network consisting of processes that arise from the lower end of the bundle branches