Blood vessel
Blood Vessel

Blood Vessel: Definition, 3 Types, Stucture, Function, Characteristics, and System

Blood vessel definition

Blood vessels are organs of the body that have a tube-like structure, responsible for draining blood throughout the body. The role of this organ is very important in the circulatory system.

Blood Vessel Types

There are three main types of blood vessels:

  • Arteries,
  • Capillary, and
  • Veins / pulse.

Arteries are responsible for draining blood from the heart, while capillary allows the exchange of water and other body substances between the blood and surrounding tissues. Meanwhile, the pulse is responsible for draining blood from the capillary back to the heart.

Arteries and pulses consist of three layers, namely tunica intima, tunica media, and tunica adventitia. Inside the arteries, the thickest layer is the tunica media or middle layer, made of connective tissue, fiber, and polysaccharides. Inside the pulse, the thickest layer is tunica adventitia, made of connective tissue and nerves. While capillary, is a thin layer made of endothelium and connective tissue.

In addition to the three main types of blood vessels, the body also has a network of small blood vessels called arterioles and venules. Arterioles are small branches of arteries, while venules are small branches that collect blood from organs up to the veins. The size of the smallest blood vessels is only about five micrometers.

Blood vessels contract and enlarge with the help of surrounding muscles. This is done to ensure there is enough pressure on the blood vessels to help pump it throughout the body.

Artery blood vessel and their function

An artery is a thick-walled structure that transports blood from the heart and has spread to various tissues of the body through its branches.

Arteries with a diameter of approximately 25mm (1 inch) have many branches. And the branch is divided into smaller blood vessels, arteries and arterioles measuring 4mm (0.16 inches) that drain blood until it reaches the tissues. In the tissues, the blood vessels are further divided, reaching a smaller diameter, approximately 30 micrometers of which are called arterioles.

Arterial Function

Arteries are blood vessels that have muscles and thick walls. The function of these vessels is to carry oxygen-containing blood from the heart throughout the body. In addition, arteries also serve to transport nutrients needed by the body. To be distributed to the parts of the body that need it.

Function of Veins

This vessel that carries blood from all parts of the body to the heart. Veins carry blood that contains a lot of carbon dioxide. The location of the veins is on the surface of the skin, the color looks like bluish. These vessels have very thin walls and are not elastic like arteries.

Learn more about Differences between veins and arteries

Blood vessel structure

Tunica Intima

Tunica intima is the deepest layer of blood vessels consisting of a layer of endothelial cells that confines the inner surface of the vessel. There is a subendothelial layer under the endothelial layer. This layer plays a role in the contraction of blood vessels.

Tunica Media

This layer is on top of the tunica intima and is the middle layer of the blood vessels. Tunica media is composed of smooth muscle fibers that are circular. Tunica media is separated by an internal elastic lamina membrane containing elastic and porous fibers, so that substances can enter through the pore. While limiting tunica media with tunica adventitia is external elastic lamina.

Tunica Adventitia

It is the outermost layer of blood vessels and contains a lot of collagen connective tissue, especially type 1 collagen and elastic tissue.

Arteriovenous Anastomosis

It is a direct connection between the artery and the vein. Arteriovenous anastomosis is distributed throughout the body and is usually present in small vessels, such as in the nails, fingers, and ears. Anastomosis is innervated by the autonomic nervous system (sympathetic and parasympathetic). Arteriovenous anastomosis is also a role in the temperature management system (thermoregulator).

Vasa Vasorum

Vasa Vasorum is a small blood vessel that provides metabolite supply for cells in tunica media and tunica adventitia large blood vessels, both arteries and veins.

What are the characteristics of blood vessels?

  • The blood vessel wall tone is regulated by platelets.
  • Blood vessels can experience dilation and narrowing regulated by medulla oblongata.
  • Found in the skin dermis and serous tissue.

Blood Vessel System


Vessels with a diameter of more than 0.1 mm. For example, large arterioles, muscular arteries, and muscular veins.


Only the surrounding tissue is visible under a microscope. It is important as a place of exchange between the blood and surrounding tissues under normal circumstances and inflammatory processes. Examples are found in arterioles, capillary, and postcapillary venules.

Last Updated on January 4, 2021 Reviewed by Market Health Beauty Team

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