I. LOCATION OF THE HEART
The heart is located in the chest between the lungs behind the sternum and above the diaphragm. It is surrounded by the pericardium. Its size is about that of a fist, and its weight is about 250-300 g. Its center is located about 1.5 cm to the left of the midsagittal plane. Located above the heart are the great vessels: the superior and inferior vena cava, the pulmonary artery and vein, as well as the aorta. The aortic arch lies behind the heart. The esophagus and the spine lie further behind the heart.
II. FUNCTIONS OF THE HEART The role of circulation is to: 1. Continuously deliver oxygen, nutrients, hormones, and antibodies to organs, tissues and cells throughout the body in response to varying tissue demands. 2. Remove end products of metabolism from tissue and cells.
The role of the heart is to: 1. Pump oxygenated blood into the arterial system, where it is carried to the capillaries supplying tissues. 2. Collect oxygenated-poor blood from the venous system and pump it through the lungs to be re-oxygenated.
The role of the blood vessel (arteries, capillaries, veins) is to carry blood to and from the bodies, tissues and cells.
III. ANATOMY OF THE HEART
The walls of the heart are composed of cardiac muscle, called myocardium. It also has striations similar to skeletal muscle. It consists of four compartments: the right and left atria and ventricles. The heart is oriented so that the anterior aspect is the right ventricle while the posterior aspect shows the left atrium. The atria form one unit and the ventricles another. The left ventricular free wall and the septum are much thicker than the right ventricular wall. This is logical since the left ventricle pumps blood to the systemic circulation, where the pressure is considerably higher than for the pulmonary circulation, which arises from right ventricular outflow.
The heart has four valves. Between the right