A "Pacemaker" can be external or internal and usually generates electrical stimuli to the heart muscle with :

A "Pacemaker" can be external or internal and usually generates electrical stimuli to the heart muscle with an electrode.

Explanation:

Pacemakers allow you to perceive when the heart is beating irregularly or very slowly. This small device sends an electrical signal or electrical impulses to the heart, which makes it beat at the normal rate, because the electrical impulses are transmitted to the heart muscle; by means of an electrode that connects the device with the heart muscle functionally thus an adequate functionality of the heart.

The pacemaker is able to detect heartbeat failures and, at that time, sends an electrical signal through the wires (electrodes) so that the heart contracts. Pacemakers may have more than one electrode depending on the number of areas of the heart that we need to stimulate.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

above statement is not a true statement about the open ocean because the open ocean has low levels of nutrients. most of the photosynthetic activity on earth occurs in the open ocean within the photic zone. organisms in the deep ocean are exposed to frigid temperatures and total darkness but it does not begin at the low-tide mark.