Blood vessels

Nov 01, 2022, 16:45 IST

The human circulatory system consists of the blood cells, heart, lymphatic system, and the network of blood vessels. All these four main organs have specific functions and roles, which work together to keep us healthy and active. Have you ever think what would happen if the blood vessels did not perform for a few seconds? Yes, we will die from Sudden Cardiac Arrest (SCA). Let’s discuss in detail the blood vessels and also their types.

Angiology is the branch of human science or anatomy that deals with studying a circulatory system, arteries, veins, blood cells, and diseases related to the circulatory system.

What are Blood Vessels?

The networks of the hollow tubes, like pipes, that carry the blood to and also from all parts of the body are known as blood vessels. These vessels have the blood in both the directions, i.e., from the heart to all the other parts and another from all the body parts to the heart.

Types of Blood Vessels

Following are the types of blood vessels are:


Arteries are the blood vessels that transport and carry oxygenated or oxygen-rich blood from the heart to the other body parts. They are the strongest blood vessels with thicker walls and are muscular. It consists of three distinct layers: rigid, thicker, and highly muscular. Arteries are located deep in the body and are red. These blood vessels are under high pressure and travel downward from the heart to the body tissues.


Veins are thin, tubular elastic blood vessels present closer to the skin's surface. These translucent blood vessels are blue in color and carry impure or deoxygenated blood from all body parts to the heart. These blood vessels are of low pressure and travel upwards, i.e., from cells, tissues, and other organs to the heart. Compared to arteries, veins are thin-walled.


The short and tiny blood vessels found in tissues are called capillaries. Capillaries ensure the exchange of substances between blood and tissues. These blood vessels also function to connect the arterial systems to the venous system and aid in the exchange of substances between cells.

Layers of Blood Vessels

Both the arteries and veins consist of the three layers.

  1. Tunica Intima- It is the thinnest and innermost layer of the arteries and the veins, which have direct contact with the flow of blood.
  2. Tunica Externa- It is also present adjacent to the tunica media and is also composed of collagen and functions by the supporting the elastic lamina in arteries. It is also known as tunica adventitia.
  3. Tunica Media- It is the middle layer of an vein or artery, which is also made up of smooth muscle cells.

Functions of Blood Vessels

  • Blood vessels play an important role in the gaseous exchange.
  • Blood vessels also help to maintain a constant internal temperature of an organism.
  • The essential function of the blood vessels is to protect against blood loss during injuries.
  • Blood vessels also circulate deoxygenated (impure) and oxygenated (poor) blood from and to the heart.
  • Blood vessels help transport water, nutrients, hormones, minerals and all the other essential components required for the different body's metabolism.

Frequently Asked Question (FAQs)

Q1. What are the functions of blood vessels?

Ans. The blood vessels are the channels through which blood is collected and distributed from the entire body to and from the heart.

Q2. What are the 3 types of blood vessels?

Ans. Three types of blood vessels are veins, arteries and capillaries.

Q3. What is the smallest blood vessel?

Ans. Capillaries

Q4. What factors affect blood vessels?

Ans. Five variables influence the blood flow and blood pressure:

  1. Cardiac output
  2. Blood vessel length and diameter
  3. Volume of the blood
  4. Compliance
  5. Viscosity of the blood

Q5. What is the largest blood vessel?

Ans. The aorta

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