EKG week 1 Reading Knowledge Assessment Chp 2

What ion enters the myocardial cells to make the heart contract?

Calcium

The normal pacemaker of the heart is the , which is found in the .

SA node; right atrium

The ability of cardiac pacemaker cells to create an electrical impulse without being stimulated from another source is called :

automaticity

The Purkinje fibers distribute an electrical impulse at an inherent rate of __.

20-40 bpm

Vagus nerve stimulation __ heart rate.

decreases

What part of the ECG tracing represents repolarization of the Purkinje fibers?

U wave

When stimulated, the sympathetic system of the body causes the heart rate to:

increase

The PR interval is usually __.

0.12-0.20 sec

Which vessel of the body contains the highest concentration of oxygen?

AO

Which would most likely increase the heart rate?

stress, exercise, fever