Difference Between Veins and Arteries

Main Difference – Veins vs Arteries

Veins and arteries are the two types of blood vessels in a closed circulatory system. The main function of blood vessels is to carry blood throughout the body. But, arteries and veins differ from their structure and function. Veins consist of a thin, elastic muscular layer in their wall while arteries consist of a thick, elastic muscle layer. The thick wall of the artery is important in handling the high pressure of the blood released by the heart. Veins carry oxygen-depleted blood towards the heart while arteries carry oxygenated blood away from the heart. The main difference between veins and arteries is that veins are involved in removing the cellular wastes from the extracellular environment whereas arteries are involved in providing nutrients and oxygen to the body cells.

Key Areas Covered

1. What are Veins
      – Definition, Features, Function
2. What are Arteries
      – Definition, Features, Function
3. What are the Similarities Between Veins and Arteries
      – Outline of Common Features
4. What is the Difference Between Veins and Arteries
      – Comparison of Key Differences

Key Terms: Aorta, Arteries, Arterioles, Blood Capillaries, Blood Pressure, Closed Circulatory System, Veins, Venules

What are Veins

Veins are a type of blood vessels that carry oxygen-depleted blood towards the heart. A vein is composed of thin, elastic blood vessels. The pressure of the blood carried by a vein is 5 mm Hg. The blood in veins flows with the help of muscular contractions. The diameter of a vein can vary from 1 mm to 1.5 cm. Venules are the smallest veins branching from a vein. The venules receive blood from capillaries. The blood in veins is received by the vena cava. The vena cava transmits blood to the superior vena cava and inferior vena cava and ultimately to the right atrium of the heart.

Figure 1: Microcirculation

The four types of veins found in a circulatory system are systematic, pulmonary, superficial, and deep veins. The systemic veins carry oxygen-depleted blood from the body to the heart. The pulmonary veins carry oxygenated blood from lungs to the left atrium of the heart. The veins which are closely located to the skin are superficial veins. The veins which are located in deep muscles are called deep veins. The involvement of veins, blood capillaries, and arteries in the microcirculation is shown in figure 1.

What are Arteries

The arteries are the other type of blood vessels in the circulatory system that carries the oxygenated blood away from the heart. Arteries are composed of thick, elastic walls. Typically, the blood pressure of an artery is 120 mm Hg. The two types of arteries in the body are pulmonary arteries and systemic arteries. The pulmonary arteries take oxygen-depleted blood from the heart to the lungs. The systemic arteries carry the oxygenated blood from the heart to the rest of the body. The largest artery in the body is aorta, and it starts from the heart. The aorta branches into arteries to carry blood throughout the body.

Figure 2: Artery Wall

The main artery that supplies blood to the brain is called the brachiocephalic artery, and the main artery that supplies blood to the heart and the lower areas of the body is called the coronary artery. The arterioles are branched from the artery. The structure of an artery wall is shown in figure 2.

Similarities Between Veins and Arteries

Veins and arteries are involved in carrying blood throughout the body in a closed circulatory system.
The wall of both veins and arteries consist of three layers; tunica adventitia, tunica media, and tunica intima.
Both veins and arteries play a major role in the circulation of materials throughout the body.

Definition

Veins: Veins refer any of the tubes forming part of the blood circulation system of the body, mainly carrying oxygen-depleted blood towards the heart.

Arteries: Arteries refer to any of the tube forming part of the cardiovascular system, carrying the oxygenated blood away from the heart.

Direction of the Flow

Veins: Veins carry blood towards the heart.

Arteries: Arteries carry blood away from the heart.

Oxygen Concentration

Veins: Typically, the oxygen concentration of the blood carried by the veins is less.

Arteries: The oxygen concentration of the blood carried by the arteries is high

Anatomy

Veins: Veins consist of a thin, elastic muscle layer and semilunar valves.

Arteries: Arteries consist of a thick, elastic muscle layer.

Thickest Layer

Veins: The thickest layer of the wall of veins is tunica adventitia.

Arteries: The thickest layer of the wall of arteries is tunica media.

Lumen

Veins: The lumen of a vein is large.

Arteries: The lumen of an artery is small.

Location

Veins: Veins are found near the skin.

Arteries: Arteries are found deeper in the skin.

Color

Veins: Veins are blue in color.

Arteries: Arteries are red in color.

Valves

Veins: Veins consist of semilunar valves.

Arteries: Arteries lack valves.

Blood Pressure

Veins: The blood pressure of veins is low (5 mm Hg).

Arteries: The blood pressure of arteries is high (120/80 mm Hg).

Amount of Blood

Veins: Around 65% of the body’s blood supply is found in the veins.

Arteries: Around 15% of the body’s blood supply is found in the arteries.

Movement

Veins: Veins exhibit a sluggish movement of blood.

Arteries: Arteries exhibit a spurty movement of blood

Pulse

Veins: The pulse of the veins is not detectable.

Arteries: The pulse of arteries is detectable.

Contraction of muscles

Veins: Veins do not exhibit muscular contractions.

Arteries: Arteries exhibit muscular contractions.

Driving Force of the Blood

Veins: The driving force of blood in veins is the muscular movements of the body.

Arteries: The driving force of blood in arteries is the pumping pressure of the heart.

Role

Veins: The major function of a vein is to remove cellular wastes from the extracellular environment.

Arteries: The major function of an artery is to provide nutrients and oxygen to the body cells.

Types

Veins: The four types of veins are superficial veins, pulmonary veins, deep veins, and systemic veins.

Arteries: The two types of arteries are pulmonary and systematic arteries.

Diseases

Veins: The disease associated with veins is deep vein thrombosis.

Arteries: The disease associated with arteries is atherosclerosis and atherogenesis.

Conclusion

Veins and arteries are the two types of blood vessels found in a closed circulatory system. The veins carry oxygen-depleted blood towards the heart while arteries carry oxygenated blood away from the heart. The veins consist of thin walls whereas arteries consist of thick walls. The blood pressure of a vein is less than the blood pressure of an artery. The main driving force of blood in veins is the muscular movements while that of arteries is the pumping pressure of the heart. The main function of veins is to remove the waste materials from the external environment of the body cells whereas that of arteries is to provide nutrients and oxygen to the body cells. Therefore, the main difference between veins and arteries is the function of each type of blood vessel in the circulatory system of the body.

Reference:

1.Bailey, Regina. “Types of Veins That Keep Your Heart Ticking.” ThoughtCo, Available here. Accessed 22 Aug. 2017.
2.Bailey, Regina. “What Is an Artery?” ThoughtCo, Available here. Accessed 22 Aug. 2017.

Image Courtesy:

1. “Blood vessels-en” By Kelvinsong – Own work (CC BY-SA 3.0) via Commons Wikimedia
2″ Blausen 0055 ArteryWallStructure” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia