Cardiovascular system includes heart and blood vessels. Heart pumps blood into the blood vessels. Blood vessels circulate the blood throughout the body Blood transports nutrients and oxygen to the tissues and removes carbon dioxide and waste products from the tissues.
Heart is the muscular organ which pumps blood throughout the circulatory system of our body. It is situated in between two lungs in the mediastinum. It is made up of four chambers, two atria and two ventricles. The musculature of ventricles is thicker than that of atria. The force of contraction of the heart depends on the muscles.
Right Side Of The Heart:
Right side of the heart has two chambers, right atrium and right ventricle. Right atrium is a thin walled and low pressure chamber. It has got the pacemaker known as sinoatrial node that produces cardiac impulses and atrioventricular node that conducts the impulses to the ventricles. Right atrium receives venous (deoxygenated) blood via two large veins:
- Superior Vena Cava that returns venous blood from the head, neck and upper limbs.
- Inferior Vena Cava that returns venous blood from lower parts of the body.
Right atrium communicates with right ventricle through tricuspid valve. Wall of right ventricle is thick. Venous blood from the right atrium enters the right ventricle through this valve. From the right ventricle, pulmonary artery arises. It carries the venous blood from right ventricle to lungs. In the lungs, the deoxygenated blood is oxygenated.
Left Side Of The Heart:
Left side of the heart has two chambers, left atrium and left ventricle. Left atrium is a thin walled and low pressure chamber. It receives oxygenated blood from the lungs through pulmonary veins. This is the only exception in the body, where an artery carries venous blood and vein carries the arterial blood.
Blood from left atrium enters the left ventricle through mitral valve (bicuspid valve). Wall of the left ventricle is very thick. Left ventricle pumps the arterial blood to different parts of the body through systemic aorta.
Septa Of The Heart:
Right and left atria are separated from one another by a fibrous septum called Interatrial Septum. Right and left ventricles are separated from one another Interventricular Septum. The upper pan is a membranous structure, whereas the lower is muscular in nature.