Mounds in the water form in areas where the water meets land, where water is warmer, or where two currents converge. Gravity then pushes this water down slope on the mounds and creates currents. Deep water currents, also called thermohaline circulation, are found below 400 meters and make up about 90% of the ocean. Like surface currents, gravity plays a role in the creation of deep water currents but these are mainly caused by density differences in the water.
The pacemaker of the heart is a bundle of cells that tells the  heart when to beat. These cells are connected to the rest of the  cells of the heart and communicate with theâ¦m through electrical  signals. The pacemaker cells set the pace (or rate) of the  heartbeat.    The actual structure that serves as the heart's primary pacemaker  is called the sinoatrial node (SA node).
1 Your heartbeat is sometimes normal and sometimes too fast or too slow. 2  The sinoatrial (SA) node or sinus node is the heart's natural pacemaker. 3  It's a small mass of specialized cells in the top of the right atrium (upper chamber of the heart). 4  It produces the electrical impulses that cause your heart to beat.