#Essential anatomy 3 heart quiz series

This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated. The AV node serves as a gate that slows the electrical current before the signal is permitted to pass down through to the ventricles.The electrical signal generated by the sinus node moves from cell to cell down through the heart until it reaches the atrioventricular node (the AV node), a cluster of cells situated in the center of the heart between the atria and ventricles.(The sinus node is also called the sinoatrial node.) The electrical impulses are generated there. The sinus node is a cluster of cells situated in the upper part of the wall of the right atrium. The sinus node is the heart's natural pacemaker.Among the major elements in the cardiac conduction system are the sinus node, atrioventricular node, and the autonomic nervous system. Heart muscle contracts in response to the electrical stimulus received system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. Heart Conduction System Īn electrical conduction system regulates the pumping of the heart and timing of contraction of various chambers. In fact, it will beat faster than normal, since there is normally a parasympathetic supply slowing the heart down. If you sever all the nerves to the heart, then it will continue to beat. The heart itself has a natural pacemaker, the sinoatrial node, which does not need a nervous supply to function.The parasympathetic system works in reverse in order to slow the heart rate down.The sympathetic nervous system acts on the sinoatrial node, speeding up the depolarisation rate, and therefore increasing the heart rate.The sympathetic fibres arise from the pressor centre, while the parasympathetic fibres arise in the depressor centre. The nervous supply to the heart is autonomic, consisting of both sympathetic and parasympathetic parts. Together they are called the cardioregulatory centre, since they interact to control heart rate, etc. There is an area called the cardioacceleratory centre, or pressor centre, in the upper part of the medulla oblongata, and an area called the cardioinhibitory centre, or depressor centre, in the lower part. The main control of the heart resides with the medulla oblongata. Tracheobronchial nodes, located at the distal end of the trachea.Brachiocephalic nodes, in front of brachiocephalic veins.Venous drainage is via the variable coronary veins and the coronary sinus. See also Coronary Artery Disease Venous drainage and Lymphatics Image: Overview of the coronary arteries and cardiac veins - anterior and posterior views Other small veins, called thebesian veins, open directly into all four chambers of the heart. Most coronary veins coalesce into the coronary sinus that runs in the left posterior atrioventricular groove and opens into the right atrium. Right coronary artery: branches supply the right ventricle, right atrium, and left ventricle's inferior wall.Ĭoronary arteries and veins course over the surface of the heart. Circumflex coronary artery that supplies blood to the lateral and posterior portions of the left ventricle.Ģ.Left anterior descending artery that supplies anterior two-thirds of the inter-ventricular septum and adjoining part of the left ventricular anterior wall.It is a short artery that divides into two branches Left main coronary artery carries 80% of the flow to the heart muscle.The heart is supplied by two coronary arteries: The left ventricle pumps blood through the aortic semilunar valve into the ascending aorta to supply the body.The left atrium pumps blood through the bicuspid (mitral) valve into the left ventricle.Blood returning from the lungs drains into the left atrium via the four pulmonary veins.The right ventricle pumps blood through the pulmonary semilunar valve into the pulmonary trunk to be oxygenated in the lungs.The right atrium pumps blood through the tricuspid valve into the right ventricle.Venous blood returning from the body drains into the right atrium via the SVC, IVC and coronary sinus.

#Essential anatomy 3 heart quiz series

It is best to remember the four chambers and four valves in order of the series that blood travels through the heart: The heart, therefore, consists of four chambers: The heart is subdivided by septa into right and left halves, and a constriction subdivides each half of the organ into two cavities, the upper cavity being called the atrium, the lower the ventricle.