Deep to the fibrous pericardium is the slippery, two-layer serous pericardium, where its parietal layer lines the interior of the fibrous pericardium. The loosely fitting superficial part of this sac is referred to as the fibrous pericardium, which helps protect the heart and anchors it to surrounding structures such as the diaphragm and sternum. The heart is enclosed in a double-walled sac called the pericardium which is the outermost layer of the heart. Its broad posterosuperior aspect, or base, from which the great vessels of the body emerge, points toward the right shoulder and lies beneath the second rib. Its more pointed apex is directed toward the left hip and rests on the diaphragm, approximately at the level of the fifth intercostal space. Snugly enclosed within the inferior mediastinum, the medial cavity of the thorax, the heart is flanked on each side by the lungs. Approximately the size of a person’s fist, the hollow, cone-shaped heart weighs less than a pound. The modest size and weight of the heart give few hints of its incredible strength. The cardiovascular system can be compared to a muscular pump equipped with one-way valves and a system of large and small plumbing tubes within which the blood travels. The heart separates the pulmonary and systemic circulations, which ensures the flow of oxygenated blood to tissues. The valves of the heart secure a one-way blood flow through the heart and blood vessels.

Contractions of the heart produce blood pressure, which is needed for blood flow through the blood vessels. Variations in the rate and force of heart contraction match blood flow to the changing metabolic needs of the tissues during rest, exercise, and changes in body position. The functions of the heart are as follows: Capillary Exchange of Gases and Nutrients.Intrinsic Conduction System of the Heart.Major Veins of the Systemic Circulation.Major Arteries of the Systemic Circulation.

Like the bustling factory, the body must have a transportation system to carry its various cargos back and forth, and this is where the cardiovascular system steps in. The almost continuous traffic into and out of a busy factory at rush hour occurs at a snails’ pace compared to the endless activity going on within our bodies.

Simple heart blood flow diagram