Anatomy of the Heart
The heart is cone-shaped, four-chambered muscular organ and sized about a man’s fist. It weighs about 250–300 g. The heart is located in the chest area, between the lungs with two-thirds of the mass towards the left midline and its apex pointing towards the left. The walls of the heart are composed of cardiac muscles. The heart is enclosed in a pericardial sac and is lined by serous membrane. The serous membrane consists of parietal and visceral layer. The visceral layer forms the epicardium. The heart consists of three layers.
- Epicardium—Outer layer
- Myocardium—Middle layer
- Endocardium—Inner layer
Internally, the heart is divided into four chambers
-
Right atrium
-
Right ventricle
-
Left atrium
-
Left ventricle
The right atrium receives deoxygenated blood from the superior and inferior vena cava. The left atrium receives oxygenated blood from the pulmonary veins. The walls of the atria are thin. The walls of the ventricle are thick and pump the blood forcefully out of the heart.
The heart has two types of valves to maintain the flow of blood in the correct direction.
- Atrioventricular valves: They are present between the atria and the ventricles.
- Semilunar valves: They are the valves present at the bases of large vessels leaving the ventricles.
Tricuspid valve is the right atrioventricular valve. Mitral or bicuspid valve is the left atrioventricular valve. The pulmonary semilunar valve is the one present between the right ventricle and pulmonary trunk. The aortic semilunar valve is the valve between the left ventricle and the aorta.
When the ventricles contract, atrioventricular valves close to prevent blood flow back into the atria. When the ventricles relax, semilunar valves close to prevent blood from flowing back into the ventricles.1
Written by: Healthplus24 team
Date last modified: July 01, 2011