Deck 31: Conduction System of the Heart and Electrocardiography

Question 1

The function of the intrinsic conduction system is to .

A) ensure that the heart beats in a sequential and coordinated manner
B) carry branches of the autonomic nervous system to heart muscle
C) maintain the structural integrity of the atria and ventricles
D) contract slightly before the cardiac tissue to which it is connected

Answer 1

A

Question 2

A health care provider who suspects that a patient is having a heart attack will look very carefully at this portion of the ECG.

A) S-T segment
B) P-R interval
C) QRS complex
D) Q-T interval

Answer 2

A

Question 3

The P wave of the ECG represents .

A) depolarization of the atria
B) depolarization of the ventricles
C) repolarization of the atria
D) repolarization of the ventricles

Answer 3

A

Question 4

Bradycardia describes a heart rate of _.

A) over 100 beats/min
B) 60-80 beats/min
C) 80-100 beats/min
D) less than 60 beats/min

Question 5

The T wave of the ECG represents _.

A) repolarization of the ventricles
B) depolarization of the ventricles
C) repolarization of the atria
D) depolarization of the atria

Question 6

During exercise, the heart rate .

A) decreases slightly, but the contractions are stronger
B) increases proportional to the exertion involved
C) increases to a set "exercise rate"
D) decreases in inverse relation to the exertion involved

Question 7

The electrocardiogram (ECG) shows a record of .

A) electrical activity of the heart muscle
B) each heart beat (or contraction)
C) the electrical events in the intrinsic conduction system

Question 8

Ventricular fibrillation is .

A) fluttering of the atria
B) slow, strong ventricular contractions
C) strong, rhythmic atrial contractions
D) rapid, uncoordinated ventricular contractions

Question 9

In the normal heart, the has the highest rate of discharge and sets the rate of depolarization for the heart as a whole.

A) bundle branches
B) AV bundle
C) AV node
D) SA node

Question 10

In sequential order, the components of the intrinsic conduction system, beginning at the SA node, are .

A) AV node, AV bundle, bundle branches, subendocardial conducting network (Purkinje fibers)
B) bundle branches, AV node, AV bundle, subendocardial conducting network (Purkinje fibers)
C) subendocardial conducting network (Purkinje fibers), bundle branches, AV bundle, AV node
D) AV bundle, AV node, subendocardial conducting network (Purkinje fibers), bundle branches

Question 11

The middle and largest deflection wave in a normal ECG is the .

A) T wave
B) QRS complex
C) P wave

Question 12

If the AV node is damaged so that it can no longer transmit the signal from the SA node (total heart block), will the ventricles continue to contract? Why or why not?

A) No: there are no cells left to pace and coordinate the heart beat.
B) Yes: the AV bundle will keep the heart going at the usual rate.
C) Yes: however, ventricular contractions will no longer follow atrial contractions, and the rate of ventricular contractions will be significantly slowed.
D) No: the SA node must be intact to pace the system.

Question 13

A normal Q-T interval is .

A) 0.08 sec when the heart rate is 50 beats/min
B) 0.16-0.18 sec when the heart rate is 60 beats/min
C) 0.32-0.38 sec when heart rate is 70 beats/min
D) 1.0-2.0 sec when heart rate is 80 beats/min

Question 14

Atrial fibrillation is .

A) slow, strong ventricular contractions
B) strong, rhythmic atrial contractions
C) rapid, uncoordinated ventricular contractions
D) uncoordinated beating of the atria

Question 15

How does holding the breath affect heart rate?

A) heart rate increases
B) heart rate decreases
C) heart rate is unaffected by breath holding

Question 16

It the interval between R waves is on an ECG is 0.80 sec, then the heart rate is .

A) 70 beats/min
B) 80 beats/min
C) 65 beats/min
D) 75 beats/min

Question 17

The QRS complex is associated with .

A) repolarization of the ventricles
B) depolarization of the atria
C) depolarization of the ventricles
D) depolarization of the ventricular septum

Question 18

This portion of the ECG is associated with ventricular contraction.

A) Q-T interval
B) P-R interval
C) QRS complex
D) S-T segment