Types of Blood Vessels: We all have blood vessels inside our bodies and underneath our skin. These are conduits or fluid ducts that help transport blood to all the tissues in the body. These blood vessels comprise two systems that are nothing but closed loops of tubing starting from the heart and also ending back at the heart again.

This network of blood vessels in our body spans a length of almost 60,000 miles. Each type of blood vessel plays a significant role in the transportation of blood from the heart to one part of the body and similarly to all other parts as well. Please keep reading this article to learn about the different types of blood vessels and the function that each type carries out. 

What Are the Different Types of Blood Vessels?

Out of the two closed-loop systems, the first system, which comprises the pulmonary vessels, is assigned the function of transporting blood from the heart’s right ventricle, straight to the lungs, and then transporting the blood all the way back to the left atrium. 

The second system comprises the systemic vessels that have the function of transporting blood from the left ventricle to all the tissues throughout the body and then getting all the blood transported back straight to the right atrium. 

Blood vessels are classified into different types based on the type of structure they have and the function that they perform. Let us have a detailed look at the different types of blood vessels.

1. Arteries

An artery is a type of blood vessel that transports the oxygenated blood from the heart to the other parts of the body. The transportation of low-oxygenated blood to the lungs from the right ventricle is performed by the pulmonary artery. The transportation of oxygenated blood to the tissues of the body from the lungs is performed by the systemic artery. 

The pumping of blood into the elastic-like arteries from the ventricles is carried out, and these arteries keep on branching out into a network of smaller arteries until the branching out ends up in the formation of microscopic level arteries. These are called arterioles. These have a very important function of ensuring that the blood flow is regulated through the capillaries of the tissues. 

There are three layers that make up the wall of an artery. The tunica intima is the innermost layer. It is surrounded by a connective tissue membrane having elastic fibres. The tunica media is the middle layer. It is a smooth layer of muscles and also the thickest layer in the artery. It performs the function of providing support to the blood vessel and also changes the diameter of the vessel in order to regulate the flow of blood. 

The third layer is the outermost layer of the artery, which is called the tunica externa. The composition of this layer is that of connective tissues along with different quantities of fibres that are elastic and collagenous in nature. This outermost layer is very densely packed.

2. Capillaries

This type of blood vessel is the smallest and has the highest quantity of presence in the entire blood vessel network. Capillaries form the bridge that connects the vessels taking the blood away from the heart, that is the arteries, and the network of vessels responsible for carrying the blood to the heart, that is veins. The main function of capillaries is to ensure that the materials are exchanged between the blood and the cells within the tissues. 

All skeletal muscles and organs such as the liver and kidney, have a large network of capillaries associated with them. This is because they are very active when it comes to metabolic activities at a cellular level and require an abundant supply of fresh oxygenated blood. However, connective tissues do not have an abundance of capillaries associated with them. The outer layer of the skin and the cornea and lens of the eye do not have capillaries. 

3. Veins

Veins comprise the network of blood vessels that transport the blood in the direction of the heart. Once the blood has gone through the capillary network, it moves on to the smallest part of the veins, that is, venules. The blood in the venules is transported to a larger network of veins that keep increasing and growing until the blood reaches the heart. The blood that is transported from the lungs to the heart by the pulmonary vein network is rich in oxygen content. 

The blood that is transported by the systemic vein network, from the tissues throughout the body to the heart, is very less in oxygen content. This is because the oxygen-rich blood has been used up by the body to perform all the metabolic functions. 

The wall of the vein has the same three layers that make up the wall of the artery. However, the amount of smooth muscle and tissues of the connective type is lesser as compared to the arteries. Thus, the veins have thinner walls than the arteries. This is because the pressure of the blood in the veins is lesser than the pressure of the blood in the arteries. Veins can have more blood in them than arteries because their walls are thinner. 

At any instant, the entire vein network of the body has almost 70% of the total blood flowing through. Veins of the larger size have valves in them at certain locations that assist in the pumping of blood back to the heart. 

We hope that this article on the types of blood vessels has proven to be helpful to you and provided valuable insight into the topic. Always remember that understanding the basic concept and principles behind any topic or process is the key to mastering any chapter or subject.

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