The function of the EKG machine depends on the ability of the heart to produce electrical signals. The heart is composed of four chambers which make up two pumps. The right pump receives the blood returning from the body and pumps it to the lungs. The left pump gets blood from the lungs and pumps it out to the rest of the body. Each pump is made up of two chambers, an atrium and a ventricle. The atrium collects the incoming blood, and when it contracts, transfers the blood to the ventricle. When the ventricle contracts, the blood is pumped away from the heart.
The pumping action of the heart is regulated by the pacemaker region, or sinoatrial node, located in the right atrium. An electrical impulse is created in this region by the diffusion of calcium ions, sodium ions, and potassium ions across the membranes of cells. The impulse created by the motion of these ions is first transferred to the atria, causing them to contract and push blood into the ventricles. After about 150 milliseconds, the impulse moves to the ventricles, causing them to contract and pump blood away from the heart. As the impulse moves away from the chambers of the heart, these sections relax
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