Question

describe the electrical exchange that occurs during the slow potential process in the sa and av nodes

Answer 1

The electrical system of the heart is the power source that makes this possible. Your heartbeat is triggered by electrical impulses that travel down a special pathway through the heart. The impulse starts in a small bundle of specialized cells called the SA node (sinoatrial node), located in the right atrium.

The electrical conduction system of the heart transmits signals generated usually by the sinoatrial node to cause contraction of the heart muscle. The pacemaking signal generated in the sinoatrial node travels through the right atrium to the atrioventricular node, along the Bundle of His and through bundle branches to cause contraction of the heart muscle. This signal stimulates contraction first of the right and left atrium, and then the right and left ventricles. This process allows blood to be pumped throughout the body.

The conduction system consists of specialised heart muscle cells, and is situated within the myocardium. There is a skeleton of fibrous tissue that surrounds the conduction system which can be seen on an ECG. Dysfunction of the conduction system can cause irregular, fast, or slow heart [cardiac] rhythms.

The SA node is also called the sinus node. The electrical signal generated by the SA node moves from cell to cell down through the heart until it reaches the atrioventricular node (AV node), a cluster of cells situated in the center of the heart between the atria and ventricles.

The conduction system of the heart. Left: Normal excitation originates in the SA node then propagates through both atria. The atrial depolarization spreads to the AV node, and passes through the bundle of His to the bundle branches/Purkinje fibers.

AV node or atrioventricular node is known as pacesetter of the heart and it receives impulses from SA node. AV node is also part of electrical conduction system of the heart that coordinates its activity with SA node. It connects atria and ventricle electrically. AV node sets the rhythm of the heart contractions.

SA Node, also referred to as the pacemaker of the heart, coordinates heart contractions. Located in the upper wall of the right atrium, it generates nerve impulses that travel throughout the heart wall causing both atria to contract. In the upper part of the right atrium of the heart is a specialized bundle of neurons known as the SA node. Acting as the heart's natural pacemaker, the SA node "fires" at regular intervals to cause the heart of beat with a rhythmn of about 60 to 70 beats per minute for a healthy, resting heart.

AV node is located in the lower portion of the right atrium. From the AV node, a tract of conducting fibers called the atrioventricular bundle or bundle of His runs through the cardiac muscle to the top of the interventricular septum. It's the heart's electrical system. The AV node is a cluster of cells in the center of the heart between the atria and ventricles, and acts like a gate that slows the electrical signal before it enters the ventricles. This delay gives the atria time to contract before the ventricles do.