Like all body organs, the heart needs a supply of blood to bring it oxygen. It cannot get oxygen from the blood within its chambers, which passes through too quickly and under too great a pressure, and in the right side is very low in oxygen. Instead, the muscle that makes up the wall of the heart, the myocardium, receives oxygen-rich blood from a system of small arteries that branch from the aorta. These are called the coronary arteries. They cross over the hearts surface, dividing and sending tiny branches into the heart muscle. The two coronary arteries are no wider than a drinking straw.
The right coronary artery lies in a groove between the right atrium and right ventricle and loops around the lower side and to the rear of the heart like a crown. Hence the name, coronary. This artery supplies blood to the thick muscle of the right ventricle.
On the other side, the left coronary artery divides almost immediately into two large branches, one of which (the anterior descending branch) passes over the front of the heart toward the tip. The other branch (the circumflex branch) lies in a groove between the left atrium and left ventricle. This artery supplies blood to the muscle of the left ventricle. The anterior descending branch supplies the front surface and tip of the heart and the front part of the septum. The circumflex branch supplies the portion of the left ventricular wall away from the septum. From the large coronary vessels, smaller branches arise, which divide and insert into the heart muscle, supplying its nutritional needs. If a blood clot occludes some part of the coronary artery, as in coronary thrombosis or coronary embolism, the cells of the heart are deprived of oxygen and soon die. This is called myocardial infarction. Research Coronary Artery
Digoxin is one of the cardiac (or digitalis) glycosides, a closely related group of drugs having in common specific effects on the myocardium. These drugs are found in a number of plants. Digoxin is extracted from the leaves of Digitalis lanata. The term 'digitalis' is used to designate the whole group. The glycosides are composed of two portions: a sugar and a cardenolide (hence 'glycosides'). Research Digoxin
The wall of the heart is composed of cardiac muscle tissue, referred to as
myocardium. This tissue is similar to the voluntary muscles of the body. In the cardiac tissue, however, the elongated muscle cells are highly interconnected to assure the maintenance of a coordinated and orderly heartbeat. The medical term myocarditis refers to inflammation of the heart muscle. A very smooth tissue, endocardium, lines the interior chambers of the heart. This lining helps to reduce any friction that may be caused by blood that is constantly moving through the four hollow chambers of the heart. Endocarditis is an inflammation of the heart lining. This condition can cause rough spots to develop in the endocardium, which may lead to thrombosis. Research Myocardium
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Coronary Artery
