19.4 Electrical and Contractile Activity of the Heart

Question 1

systole

Answer 1

The contraction of any heart chamber; ventricular contraction unless otherwise specified.

Question 2

diastole

Answer 2

A period in which a heart chamber relaxes and fills with blood; especially ventricular relaxation.

Question 3

sinus rhythm

Answer 3

the normal heartbeat triggered by the SA node

Question 4

nodal (junctional) rhythm

Answer 4

ectopic focus of the AV node

Question 5

pacemaker potential (prepotential)

Answer 5

gradual depolarization of the cells of the SA node

Question 6

electrocardiogram

Answer 6

a composite recording of all action potentials produced by the nodal and myocardial cells

Question 7

atrial fibrillation

Answer 7

a weak rippling contraction in the atria

Question 8

heart block

Answer 8

failure of any part of the cardiac conduction system to conduct signals

Question 9

bundle branch block

Answer 9

a heart block resulting from damage to one or both branches of the AV bundle

Question 10

total heart block

Answer 10

heart block resulting from damage to the AV node

Question 11

premature ventricular contraction (PVC)

Answer 11

the result of a ventricular ectopic focus firing and setting off an extra beat (extrasystole) before the normal signal from the SA node arrives

Question 12

arrythmia

Answer 12

any deviation from regular sinus rhythm

Question 13

ventricular fibrillation

Answer 13

the hallmark of a heart attack

Question 14

cardiac arrest

Answer 14

the cessation of cardiac output

Question 15

defibrillation

Answer 15

an emergency procedure in which the heart is given a strong electrical shock with a pair of paddle electrodes