Cardiovascular system

Cardiovascular system

The cardiovascular system (cardio = related to the heart, vascular = related to the blood vessels) is composed of heart, blood vessels and the cells and plasma that constitutes the blood. It maintains the circulation of life giving blood to all parts of our body which is necessary for delivery of nutrients, removal of wastes and exchange of oxygen and carbon dioxide.

Our Heart:

It is the most important part of the cardiovascular system. It is a muscular organ located in the chest between the two lungs, slightly to the left. It is well protected by the rib cage. It pumps blood to the various parts of our body by repeated rhythmic contractions. On the average, it beats 72 times in a minute. It has four chambers – 2 upper chambers known as atria and 2 lower chambers known as ventricles. The atria receive blood and the ventricles pump blood to the various parts of our body and the lungs.

Blood vessels:
Blood vessels are the tubes that carry the blood. They are of 3 types:

1. Arteries – carry blood from the heart to different parts of our body
2. Veins – carry blood from the different parts of our body back to our heart
3. Capillaries – small, thin walled vessels that form a network between the arteries and veins in the tissues and function in the exchange of nutrients and gases.

Blood:
Blood is a specialised body fluid that flows through the blood vessels. It derives its red colour from the presence of the pigment hemoglobin in the red blood cells – which is responsible for the transport of oxygen and carbon dioxide. Blood is composed of the fluid part known as plasma and blood cells. Plasma is mostly made up of water and also contains proteins, salts and other substances. The blood cells are of 3 types – Red blood cells (responsible for the transport of respiratory gases), White blood cells (responsible for immunity against diseases) and platelets (responsible for blood clotting.)

Systemic Circulation and Pulmonary Circulation

These are two divisions of the cardiovascular system. Systemic circulation is concerned with the delivery of oxygenated blood to the various parts of our body. Here the blood from the left ventricle is pumped to the various parts of the body through the aorta. After circulating through the body, the blood reaches the right atrium through the superior vena cava and inferior vena cava.

Pulmonary circulation is concerned with the oxygenation of blood in the lungs. The blood from the right ventricle is pumped to the lungs via the pulmonary artery where it gets oxygenated and it reaches the left atrium via the four pulmonary veins.