The cardiovascular system is the system of blood circulation. The term “cardiovascular” is a combination of two word: “Cardio” and “vascular”. The term “cardio” is derived from “cardiac” meaning Heart; and the term “vascular” means blood vessels. So the name indicates that cardiovascular systems is the system of heart and blood vessels. Cardiovascular system is also known as “Circulatory System”. So, Cardiovascular system is made up of three major components: Heart, Blood vessels and blood.

HEART:The centre of the circulatory system is the heart. The heart is one of the most important organs in the human body. Heart is a hollow muscular organ made of strong cardiac muscles. Heart can push the blood through the circulatory system with great force. It pumps blood throughout the body, beating approximately 72 times per minute of our lives. The pumping of the heart is called the Cardiac Cycle. The heart pumps the blood, which carries all the vital materials which help our bodies function and removes the waste products that we do not need.

Make-up of the Heart:

The walls of the heart are made up of three layers, while the cavity is divided into four parts. There are two upper chambers, called the right and left atria, and two lower chambers, called the right and left ventricles. The Right Atrium, as it is called, receives blood from the upper and lower body through the superior vena cavaand the inferior vena cava, and from the heart muscle itself through the coronary sinus.

The right atrium is the larger of the two atria, having very thin walls. The right atrium opens into the right ventricle through the right atrioventicular valve. The right ventricle pumps the blood to the lungs to be reoxygenated. The left atrium receives blood from the lungs via the four pulmonary veins. It is smaller than the right atrium, but has thicker walls. The left ventriclepumps the blood throughout the body. It is the Aorta, the largest artery in the body, which originates from the left ventricle.

The Heart works as a pump moving blood around in our bodies to nourish every cell. Blood that has been reoxygenated by the lungs is drawn into the left side of the heart and then pumped into the blood stream. It is the atria that draw the blood from the lungs and body, and the ventricles that pump it to the lungs and body.

BLOOD VESSELS:Human beings have a closed type of circulatory system in which blood does not come in direct contact with body tissues. Instead the blood flows in restricted pathways called blood vessels. Materials are exchanged between blood and body tissues through the walls of blood vessels. Thus blood vessels are pathways of blood flow in human body. There are three main types of blood vessels: Arteries, Capillaries and Veins.

The Arteries carry oxygenated blood. They are narrow, but thick so they are able maintain high blood pressure and withstand that pressure.

The Capillaries are the smallest of the blood vessels and serve as the connection between the
arterial and venal systems of the cardiac system.

The Veins carry deoxygenated blood; very dilate and thin. They carry
blood to the heart. They receive blood from capillaries after the exchange of oxygen and carbon dioxide takes place.

BLOODis a specialized tissue of body that exists in fluid form. It is one of the five basic types of tissues of human body. Blood consists of two major portions: Blood cells and Plasma. Plasma is the watery portion of blood that makes it a fluid. 90% of blood plasma is water and remaining 10% are proteins, inclusions and waste products etc. Blood cells are of three main types: Red Blood Cells (RBCs), White Blood Cells (WBCs) and Platelets.

Cardiovascular system is so important for human body, that if it stops for a minute, rapid death will occur. The flow of blood is necessary for existence of life. If the flow of blood is stopped, life will stop. Heart is the main organ of cardiovascular system and it is responsible for distributing blood all over human body.

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