The cardiovascular system is a part of the circulatory system and it includes the heart, blood, and blood vessels that transport the blood. The heart is an important organ of the cardiovascular system that performs a continuous pumping action.

Circulatory system is a transport system of the body which performs an important function in the body by delivering nutrition and oxygen to every cell and tissue of the body through the blood. To fulfill all these needs of the body, blood is transported throughout the body and circulates in the blood vessels. The heart pumps continuously to circulate the blood in the blood vessels.

• Blood Vessels..

Blood circulates throughout the body through blood vessels. The heart performs a pumping action

Artery..

Branches of blood vessels that carry blood from the heart to the body are called arteries. Blood flows from the heart to the body.Primarily arteries carry oxygenated blood to every cell and tissue in the body. Along with oxygen in this blood, nutrient material also reaches every cell tissue.

There are mainly two types of arteries in the body.

1. Pulmonary artery: This artery contains deoxygenated blood. which carries blood from the heart to the lungs to be oxygenated. It carries deoxygenated blood. All the arteries of the body with one exception.

2. Systemic artery: This includes all the arteries inside the body. It starts from the left ventricle of the heart. Oxygenated blood from the left ventricle circulates throughout the body through an artery called the aorta. The aorta is the largest branch of all arteries and carries oxygenated blood to all these systemic arteries.

Arterioles..

Arterioles are small branches of arteries. Which mainly divides from the artery and forms. Its diameter is similar to that of an artery and oxygenated blood mainly flows through it. Which works to deliver oxygenated blood to every cell and tissue of the body.

Capillaries..

Capillaries are the microscopic structures of blood vessels. which is located at the ends of arterioles and venules. These capillaries are connected to the cell to exchange gases and other nutritional materials. These capillaries do not have all the layers found inside blood vessels but only a single layer of epithelium so that the exchange of substances between the blood and cells can take place easily.

Venules…

Capillaries that bring deoxygenated blood from cells and tissues join together to form venules. These venules join into smaller branches and further form larger veins that help transport deoxygenated blood to the heart.

vein…

The vessels that carry deoxygenated blood from different parts of the body to the heart are called veins. Smaller venules join to form larger veins and carry deoxygenated blood to the right atrium of the heart. Among all the veins in the body, the superior and inferior vena cava are the main veins. All of which carry deoxygenated blood from the body parts to the heart.

The pulmonary vein carrying oxygenated blood from the lungs brings oxygenated blood to the left atrium of the heart. Of all the veins in the body, this vein carries exceptionally oxygenated blood.

Structure of the Blood Vessels…

The walls of arteries and veins are made up of three types of tissue layers. In which the outermost wall is called tunica adventitia, the middle wall is called tunica media and the inner wall is called tunica intima.

Tunica adventitia..

This is the outermost layer of blood vessels. It is made up of fibrous connective tissue. It acts to protect the blood vessels from the outside.

Tunica Media..

This is the middle layer of blood vessels. It is composed of smooth muscles and elastic connective tissue.. As this layer is more abundant in large arteries, dilatation and constriction are easily observed. This layer is thicker in arteries as compared to veins. As the diameter of the blood vessels decreases, this layer becomes thinner. This layer is not seen in the wall of capillaries.

Tunica intima..

This is the innermost layer of blood vessels. Which is made up of squamous epithelium tissue and is also known as endothelium.This layer is smooth and shiny and is in contact with blood.

Anastomoses and End Arteries…

Joining of two or more arteries is called anatomosis.Due to these anastomoses, any one region is supplied with blood by two or more arteries.

Alternative blood flow to any body part occurs due to anatomosis. So, the total blood circulation does not stop due to the closure of any one branch. This additional circulation is also called collateral circulation…

An artery which does not have the property of anastomosis and if a single artery supplies blood to any region is known as an end artery.

Due to obstruction in the blood flow of this artery, there are chances of damage to any cell and tissue due to lack of pulse supply.

• Control of Blood Vessels Diameter..

The diameter of the blood vessels is controlled by the automatic nervous system. Also, due to the sympathetic and parasympathetic nervous system, the diameter of the blood vessels may increase or decrease.

The vasomotor center in the medulla within the brain also controls the diameter of the blood vessels.

Apart from this, the receptors in the wall of the artery also have control over the diameter of the blood vessels.

The increase in diameter of blood vessels is called vasodilatation and the decrease in diameter of blood vessels is called vasoconstriction.

• Blood supply to the blood vessels..

Blood is supplied by a network of tiny blood capillaries on the outer wall of blood vessels called the vasa vesorum.

• Difference Between Artery and Vein

The blood vessels that carry blood from the heart to the body are called arteries, while the blood vessels that carry blood from the body to the heart are called veins.

Oxygenated blood circulates in arteries except the pulmonary artery and deoxygenated blood circulates in veins except the pulmonary vein.

Arteries do not have valves while veins do.

As the blood in the artery contains oxygen, it appears bright red in color, while the blood in the vein appears dull red or less red due to the presence of carbon dioxide.

As the artery originates directly from the heart, pulsation is heard in it, whereas no pulse occurs in the vein.

Arteries are mainly located deep in the body while veins are located superficially.

The middle layer of an artery is more elastic so that its diameter can change more while the middle layer of a vein is not as elastic as an artery.

The lumen of an artery is normally narrow while the lumen of a vein is narrow compared to that of an artery.

Blood no force is high in artery while blood no force is low in vein.

When the amount of blood in the artery is less, its wall does not shrink (collapse) due to its strength, while when the amount of blood in the vein is less, it shrinks.