The smooth innermost layer of the heart covers the inner chambers and the cardiac valves.
The mechanical structures of the heart include the heart’s layers, chambers, septum, valves, and the major vesselsSeveral major vessels enter and exit the heart. The arteries carry blood away from the heart while the veins bring blood to the heart. While memorizing the major vessels is unnecessary, having a basic picture of the major vessels is... (including the coronary arteriesThe coronary arteries provide blood to the heart tissues, carrying blood first across the epicardium, then the myocardium and finally terminating in the endocardium. The epicardium forms the outer layer of the heart. The myocardium forms the middle layer and...). Each of these structures contribute to the effective ejection of blood – the primary purpose of the heart.
The heart is encased in two protective layers. The outer layer, the pericardial sac, covers the heart. It folds in on itself at the aortaBegins with the aortic valve, the largest main vessel that carries oxygenated blood from the ventricles to the body. Major Vessels 1. Six Second ECG Guidebook (2012), T Barill, p. 15, 190 forming the epicardial surface of the heart. Between these layers is a small amount of fluid that provides a non-stick surface between these layers.
The epicardiumThe external layer that covers the heart – also called the visceral layer of the heart; between the visceral layer and the outer parietal layer is the pericardial sac; note that the coronary arteries travel along the epicardium before burrowing... forms the outer layer of the heart. The myocardiumThe muscle layer of the heart; the middle layer that is responsible for contraction of the heart. The muscular myocardium is the thickest layer and the workhorse of the heart. It is composed of specialized muscle and electrical cells that... forms the middle layer and the endocardium the innermost layer of the heart. The coronary arteries provide blood to the heart tissues, carrying blood first across the epicardium, then the myocardium and finally terminating in the endocardium.
The endocardium claims the dubious position as the terminus for the coronary arteries. Since the coronary arteries begin along the epicardial surface, enter the myocardium and terminate in the endocardium, myocardial ischemiaInsufficient supply of oxygen to meet the oxygen demands of tissue. Anaerobic metabolism becomes increasingly important during periods of ischemia. Ischemia results from an inadequate blood flow that fails to meet the oxygen demands (energy demands) of tissues. If tissues... rarely occurs without endocardial ischemia. While the endocardium is damaged in most every myocardial infarctionThe necrosis or death of myocardial tissue due to insufficient supply of oxygen to the infarcted region. The ability to identify cardiac ischemia, injury and infarction is vital in the management of the majority of cardiac emergencies. Most sudden cardiac..., the epicardium’s location in the blood flowThe purpose of the cardiac cycle is to effectively pump blood. The purpose of the cardiac cycle is to effectively pump blood. The right heart delivers deoxygenated blood to the lungs. Here oxygen is picked up and carbon dioxide is... hierarchy increases its safety factor.
The muscular myocardium is the thickest layer and the workhorse of the heart. It is composed of specialized muscle and electrical cells that are able to conduct an electrical impulse quickly and contract forcefully. The endocardium has a smooth inner surface to allow blood to flow easily through the heart’s chambers. The heart’s valves are part of the endocardium.
The endocardium releases hormones such as:
- endocardinOne of the hormones released by the endocardium is endocardin; a substance that prolongs myocardial contraction. The endocardium releases hormones such as: - endocardin, a substance that prolongs myocardial contraction; - atrial natriuretic factor (ANF), released by the atria to..., a substance that prolongs myocardial contraction;
- atrial natriuretic factorOne of the hormones released by the endocardium is atrial natriuretic factor (ANF); which is released by the atria to oppose the activity of epinephrine, endothelin and the renin-angiotensin system. The endocardium releases hormones such as: - endocardin, a substance... (ANF), released by the atriaRight and left atria (1/3 volume and muscle mass of the ventricles) pump blood to the ventricles. Chambers and Layers of the Heart 1. Six Second ECG Guidebook (2012), T Barill, p. 190 to oppose the activity of epinephrine, endothelin and the renin-angiotensin system
- brain natriuretic peptideOne of the hormones released by the endocardium is brain natriuretic peptide (BNP); which is released by the ventricles upon ventricular distention having similar effects to ANF. The endocardium releases hormones such as: - endocardin, a substance that prolongs myocardial... (BNP) which is released by the ventriclesThe larger chambers of the heart (3 times the volume and muscle thickness than the atria), responsible for the pumping of blood to the lungs and the rest of the body. upon
ventricular distention having similar effects to ANF.
The heart is not just a pump but also an endocrine organ!
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 10, 196