Heart Anatomy and Physiology, Structure and Layers of the Heart, Cardiac Cycle, Heart’s Electrical Conduction System, Starling’s Law of the Heart
Heart 1. Location and Size The heart is situated in the mediastinum (central compartment of the thoracic cavity), slightly tilted to the left. It is about the size of a closed fist and weighs approximately 250–300 grams in adults. 2. Structure and Layers of the Heart Layers : Pericardium : A double-layered sac that encases the heart. Outer fibrous pericardium protects and anchors the heart. Inner serous pericardium consists of the parietal and visceral (epicardium) layers. Epicardium : The outermost layer of the heart wall, part of the serous pericardium. Myocardium : The thick, muscular middle layer responsible for contractions. It contains cardiac muscle fibers arranged in a spiral pattern. Endocardium : The innermost layer, which lines the chambers and valves, and is continuous with blood vessels. 3. Heart Chambers Right Atrium : Receives deoxygenated blood from the superior and inferior vena cava, as well as from the coronary sinus. Right Ventric...