Question 4 (1 point) The SA node regulates temperature control in an arm the contraction of the ventricles the contraction of the atria how much blood enters the atrium when the ventricles open

The SA node regulates **the contraction of the atria**. The sinoatrial (SA) node is the natural pacemaker of the heart. It generates electrical impulses that cause the atria to contract, initiating the heartbeat.<br />