complete anatomy and physiology of the heart

The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium. Three layers of tissue form the heart wall. The visceral layer of the serous membrane forms the epicardium. The heart is enclosed in a pericardial sac that is lined with the parietal layers of a serous membrane. Collateral circulation generally develops when coronary artery disease is more advanced in older patients.The human heart is a four-chambered muscular organ, shaped and sized roughly like a man's closed fist with two-thirds of the mass to the left of midline. Also, the LCX perfuses the inferior-posterior surface of the heart in 10% of the population.Ĭoronary collaterals may exist between the RCA and the LCX to extend perfusion when one of these arteries is narrowed. In 45% of the population, the LCX perfuses the SA node, and in 10% it perfuses the AV node. The circumflex artery perfuses the lateral wall of the left ventricle. The LAD perfuses the anterior wall of the left ventricle and 2/3 of the interventricular septum. The left coronary artery (LCA) branches immediately into the left anterior descending artery (LAD) and the left circumflex artery (LCX). The SA node is perfused by the RCA in approximately 55% of the population, and the AV node is perfused by the RCA in approximately 90% of the population. In 70% of the population, the RCA is the dominant coronary artery perfusing the posterior wall of the heart. It perfuses the right atrium and the right ventricle. The right coronary artery (RCA) extends off the right side of the aorta down the inferior side of the heart across the right atrium and the right ventricle.

This allows for more time to oxygenate the myocardium between ventricular contractions. Coronary arteries receive perfusion of blood from the aorta during diastole when the ventricular myocardium is resting. Two main coronary arteries branch off the trunk of the aorta close to the aortic valve (but outside of the chambers of the heart). The cell membranes of the myocardial cells of the ventricles are repolarizing early during diastole and maintaining the resting potential later in diastole. During systole, the semilunar valves are open.ĭiastole, the longer period, is when the ventricles fill with blood, initially passively following opening of the AV valves and more completely near the end when the atria contract. The duration of systole is approximately 1/3 of the total cardiac cycle. This is when blood is ejected out of the heart into either the pulmonary or systemic circulations. Systole occurs during depolarization and contraction of the cardiac ventricles. It is pumped out of the ventricle through the aortic valve into the aortic arch and throughout the systemic circulation. The blood travels from the left atrium through the mitral (bicuspid) valve into the left ventricle.

Blood circulates through the pulmonary circulation becoming oxygenated in the capillaries around the lungs and returning to the left atrium via the pulmonary veins. From there, the blood passes through the tricuspid valve into the right ventricle, then it passes during systole through the pulmonic valve into the pulmonary artery. Cardiac veins also empty blood into the right atrium.

General Principles of Hemodynamic MonitoringĪs a reminder of the heart's A & P, blood returns to right atrium of the heart from the inferior and superior vena cavae.

Systemic Inflammatory Response Syndrome.Instrinsic Pathway of Coagulation Cascade.Circulation of Blood through the Heart (Anatomical Pathway).Vaughan Williams Classification of Antidysrhythmic Drugs.

Principles of Administration of Cardiac Medications.

Complete anatomy and physiology of the heart