Difference Between Arteries and Arterioles

Main Difference – Arteries vs Arterioles

Arteries and arterioles are two types of blood vessels that mainly carry oxygenated blood. The main difference between arteries and arterioles is that arteries are the major blood vessels that carry oxygenated blood whereas arterioles are the small branches of arteries that lead to capillaries. Both arteries and arterioles can be identified in a closed circulatory system. A closed circulatory system is mainly composed of a heart and blood vessels. The major artery which carries the oxygenated blood away from the heart is the aorta. The aorta branches into arteries to supply blood to each organ of the body. These arteries further branch into arterioles and capillaries at tissues. The main function of both arteries and arterioles is to carry nutrients and oxygen to different types of tissues in the body. 

Key Areas Covered

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

Key Terms: Aorta, Arteries, Arterioles, Atherosclerosis, Brachiocephalic Artery, Blood Pressure, Capillaries, Coronary Artery, Oxygenated Blood, Sympathetic Nervous System, Systemic Artery

What are Arteries

Arteries are elastic, muscular-walled tubes that mainly carry oxygenated blood away from the heart in the circulation system. These types of arteries are called systemic arteries. The main systemic artery that starts from the heart is called the aorta. The aorta gradually branches into several arteries, which carry blood to each organ of the body. The brachiocephalic artery carries blood to the head region. The coronary artery carries blood to the heart. Likewise, every artery that carries blood to different organs has different names. A cross-section of a human artery is shown in figure 1.

Figure 1: A Human Artery Cross-Section

These arteries further branches into arterioles and capillaries at the tissues.  

Structure of an Artery Wall

An artery wall is composed of three layers: tunica externa, tunica media, and tunica intima. The strong, outer layer of the artery wall is called the tunica externa. The tunica externa is made up of a connective tissue, containing collagen and elastic fibers. It prevents the overexpansion of blood vessels. The tunica media is the mid-layer of an artery, composing of smooth muscles. The inner layer of an artery is the tunica intima. It is composed of elastic fibers and endothelium. The structure of an artery wall is shown in figure 2.

Figure 2: Artery Wall

Atherosclerosis refers to the build-up of plaque on the inner wall of the artery. These are fat deposits and they can block the lumen of the artery, causing the decrease of the blood flow through the artery. The decrease of the blood flow to tissues can cause tissue death.

What are Arterioles

Arterioles are the small branches of arteries that lead to capillaries. Like arteries, arterioles are strong and elastic blood vessels, which are composed of smooth muscle layers. Arterioles are the most highly-regulated blood vessels in a circulation system. The constriction and the dilation of arterioles are controlled by the sympathetic nervous system. Therefore, arterioles are the major regulators of blood flow and blood pressure. The structure of an arteriole is shown in figure 3.

Figure 3: Arteriole

The blood flow through arteries is regulated based on the temperature of the external environment, food stress, physical activity, and exposure to medications or toxins. The constriction of arterioles causes the blood pressure to increase while dilation of arterioles causes the blood pressure to decrease. Atherosclerosis, as well as, arterial stenosis may affect the blood flow through the arteriole.

Similarities Between Arteries and Arterioles

• Arteries and arterioles carry oxygenated blood.
• Both arteries and arterioles occur together in a closed circulation system.
• Both arteries and arterioles are elastic blood vessels, consisting of muscular walls.
• The wall of both arteries and arterioles consist of three tunics; tunica intima, tunica media, and tunica externa.
• Both arteries and arterioles consist of a lumen.
• The main function of arteries and arterioles is to carry nutrients and oxygen to the different tissues of the body.
• Both arteries and arterioles are under the control of the sympathetic nervous system.

Difference Between Arteries and Arterioles

Definition

Arteries: Arteries are the muscular-walled tubes that mainly carry oxygenated blood in the circulation system.

Arterioles: Arterioles are the small branches of arteries that lead to capillaries.

Direction

Arteries: Arteries lead to arterioles.

Arterioles: Arterioles lead to capillaries.

Diameter

Arteries: The diameter of an artery ranges from 0.1 mm to 10 mm in muscles.

Arterioles: The diameter of an arteriole is about 30 μm.

Thickness

Arteries: The thickness of the wall of an artery is high.

Arterioles: The thickness of the wall of an arteriole is low.

Main Function

Arteries: Arteries carry blood from the heart to the different organs of the body.

Arterioles: Arterioles regulate blood pressure and blood flow.

Conclusion

Arteries and arterioles are two types of blood vessels that carry oxygenated blood throughout the body. Arteries are the branches of the aorta which comes out from the heart. Arterioles are the branches of arteries. The main difference between arteries and arterioles is the structure and function of the each type of blood vessels.

Reference:

1. Bailey, Regina. “What Is an Artery?” ThoughtCo, Available here. Accessed 18 Sept. 2017.
2. Weber, Craig. “What Is the Function of Arterioles in Blood Pressure?” Verywell, Available here. Accessed 18 Sept. 2017.

Image Courtesy:

1. “Artery” By Lord of Konrad – Own work (CC0) 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
3. “Arteriole et muscles lisses” by Servier Medical Art (CC BY 2.0) via Flickr