Question

He cells of the ___________ act as the heart's pacemaker, which establishes the pace for cardiac activity.

Answer 1

He cells of the sinoatrial (SA) node act as the heart's pacemaker, which establishes the pace for cardiac activity.
The SA node is one of the major elements in the cardiac conduction system. It consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart) and is responsible for generation of electrical impulses.

Answer 2

The cells of SA node acts as the heart's peacemaker which establishes the pace for cardiac activity.

Sinoatrial node is also called sinus node.
SA node is termed as a group of cells which are located in the wall of the right atrium of the heart. Cells have the ability to produce electrical impulse. It travels to the heart via electrical conduction system which causes it to contract.
It produces action potential and also sets the rhythm of the heart.