The key difference between artery and vein is that an artery carries oxygenated blood from the heart to the other parts of the body while a vein carries deoxygenated blood from other parts of the body to the heart.
The circulatory system consists of blood vessels and the heart. Arteries and veins are the two basic types of blood vessels that deliver blood to and from the heart. They both look like tubes, but there is a difference between artery and vein in terms of their structure and function.
CONTENTS
1. Overview and Key Difference
2. What is an Artery
3. What is a Vein
4. Similarities Between Artery and Vein
5. Side by Side Comparison – Artery vs Vein in Tabular Form
6. Summary
What is an Artery?
An artery is a type of blood vessel. All arteries except pulmonary artery carry oxygenated blood away from the heart to the systemic circulation in order to provide oxygen and nutrients to the distant tissues and organs. The largest artery leaving the heart is the aorta. As it progresses, it becomes smaller and divides into branches and then into arterioles and capillaries to form capillary beds where the exchange of substances takes place. Next, the blood flows into postcapillary venules, small veins, and large veins and eventually to superior and inferior vena cava entering the heart.
Figure 01: Artery
Furthermore, the arteries can resist high pressure as they have a thick wall composed of three layers: tunica intima, tunica media and tunica externa. Tunica interna has more elongated endothelial cells with a well-developed elastic membrane while tunica media is more muscular and has many elastic fibers. Tunica externa, which is the outermost layer of the arterial wall, is less well developed and less strong. The lumen of the arteries are narrow and do not have valves. The flow in the arteries is pulsatile; it is palpable and reflects the rhythmic pumping action of the heart. After death, arteries are found to become empty of blood.
What is a Vein?
A vein is a type of blood vessel which returns deoxygenated blood from the capillary networks to the heart to be pumped into the lungs in order to get oxygenated. However, pulmonary veins carry oxygenated blood. Blood flows passively in the veins down a pressure gradient.
Figure 02: Vein
Veins also have the general three-layer arrangement of the vessels, but the elastic and muscular components are the much less prominent features. Walls of veins are thinner and less elastic compared to an artery. In the tunica interna, endothelial cells are less flat, and the elastic membrane is less well developed. Tunica media is less muscular and has few elastic fibers. However, veins have well developed and stronger tunica externa compared to arteries. The lumen is wide and posses valves allowing a unidirectional flow of blood. Venous pulsations are not palpable but visible. Even after death, the veins contain blood.
What are the Similarities Between Artery and Vein?
- Artery and vein are two types of blood vessels and both carry blood.
- Also, both vessels have three layered walls.
- The capillary network connects arteries and veins.
- Moreover, both artery and vein transport blood unidirectionally.
- And, they comprise muscular tissue.
What is the Difference Between Artery and Vein?
Arteries carry oxygenated blood away from the heart while veins carry deoxygenated blood towards the heart. Therefore, this is the key difference between artery and vein. Also, the wall of the artery is thicker and more elastic compared to the vein. Another difference between artery and vein is that arteries are deep-seated while veins are more superficial.
Furthermore, the lumen of the artery is narrow, but in the vein, the lumen is wide. Moreover, a significant difference between artery and vein is that the arteries don’t have valves, but veins do have valves to prevent backflow. After death, the arteries become empty, but the veins do not. So, this is another interesting difference between artery and vein.
Summary – Artery vs Vein
There are three types of blood vessels, and arteries and veins are two types among them. Arteries carry blood from the heart to the other parts of the body while veins carry blood from the other parts of the body to the heart. Furthermore, arteries contain oxygenated blood, while veins contain deoxygenated blood. Also, arteries are thicker and more elastic and have a narrow lumen compared to veins. However, both consist of three-layered walls. But, arteries do not have valves while veins have valves to prevent the backflow of the blood. Thus, this is the summary of the difference between artery and vein.
Reference:
1. “What Are the Three Main Types of Blood Vessels?” WebMD, WebMD, Available here.
2. “Blood Vessel.” Wikipedia, Wikimedia Foundation, 10 May 2019, Available here.
Image Courtesy:
1. “Artery” By Kelvinsong – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Vein (retouched)” By File:Vein.svg: Kelvinsongderivative work: Begoon – This file was derived from Vein.svg (CC BY-SA 3.0) via Commons Wikimedia