Difference Between Artery and Vein

Arteries and veins supply blood to various parts of the body. They are called blood vessels because they distribute blood to various body parts.

These two structures work in synergy but they differ in so many ways. Let us dig deeper into their differences.

Arteries

Picture 1: Arteries carry oxygenated blood from the heart to various parts of the body.

Image Source: wikimedia.org

They are blood vessels that carry oxygenated blood away from the heart going to different parts of the body. Aside from the blood, they also carry other nutrients from the heart to the different tissues of the body. ^{(1, 2, and 3)}

Structures of the artery

The artery is a muscular tube. It is built that way so that it can carry the higher pressure of blood exerted by the heart during its pumping mechanism. It has three layers namely:

Intima – It is the innermost layer that gets in direct contact with the blood.
Media – It is the middle layer made up of elastic fiber and smooth muscles.
Adventitia – It is the outermost layer consists of elastic fiber, collagen, and connective tissues.^{(3, 4)}

The table below shows the three layers of the artery.

Layers of the artery	Location and components
Tunica Intima	Innermost layer/direct contact with the blood
Tunica Media	Middle layer/consists of smooth muscles and elastic fiber
Tunica Adventitia	Outermost layer/consists of elastic fiber, collagen, connective tissues

Veins

Picture 2: Veins carry deoxygenated blood from various parts of the body going back to the heart.

Image Source: study.com

They are blood vessels that carry low oxygenated blood from the different parts of the body back to the heart.

Structures of the vein

Veins have several layers namely:

Intima – The innermost layer made up of muscles and soft tissues.
Media – The thinner layer made up of elastic fiber and smooth muscles.
Adventitia – The outer covering made up of collagen, elastic fiber, and connective tissues. ^{(3, 4, and 5)}

The layers of the vein are summarized in the table below.

Layers of the veins	Location and components
Tunica Intima	Innermost layer consists of muscles and soft tissues
Tunica Media	The thinner layer consists of elastic fiber and smooth muscles
Tunica Adventitia	The outermost covering made up of elastic fiber, collagen, and connective tissues

Types of veins

Deep veins – They are located within the muscle tissues deep in the body. They carry a vast majority of the blood.
Superficial veins – They are close to the surface of the skin.
Connecting veins – The blood from the superficial veins is directed to the deep veins with the help of connecting veins.
Pulmonary veins – They are located in the lungs and each lung has two sets of pulmonary veins. Their primary function is to transport oxygenated blood from the lungs to the heart.
Systemic veins – They are all over the body and their role is to transport deoxygenated blood back to the heart. ^{(4, 5, and 6)}

Type of vein	Location	Functions
Deep veins	Within the muscles Deep in the body	Carry the vast majority of the blood
Superficial veins	Close to the surface of the skin	They are not as important as the deep vein. They carry less blood. In some cases, they are stripped to treat varicose veins.
Connecting veins	In between the superficial vein and deep vein	Serves as a junction or connection for the superficial vein and deep vein
Pulmonary veins	Located in the lungs	They transport oxygenated blood from the lungs to the heart.
Systemic veins	Found all over the body	They transfer deoxygenated blood back to the heart.

What are the similarities of veins and arteries?

They are both blood vessels which are vital in the circulatory system.
They both carry blood and other nutrients.
They are both consist of three layers.^{(5, 6)}

Picture 3: A comparison image between veins and arteries.

Image Source: ytimg.com

Picture 4: A comparison image between veins and arteries.

Image Source: skinandvein.com

Picture 5: A comparison image between a normal artery and atherosclerotic artery.

Image Source: cdc.gov

For the detailed differences between veins and artery refer to the table below.

Points of comparison	Arteries	Veins
Circulatory route	Carry blood from the heart to different parts of the body	Carry blood from the different parts of the body to the heart
Type of blood	Oxygenated blood except for the pulmonary artery	Deoxygenated blood except for the pulmonary vein
Location	Deep within the body	Closer to the surface of the skin⁽⁷⁾
Valves	Arteries have valves	Veins do not have valves
Blood Pressure	High pressure is needed for the blood to flow through	Low pressure is enough for the blood to flow through
Color	Reddish	Bluish/purplish
Ability to detect pulse	Palpation of the artery will help detect pulse	Pulse is not detectable
Wall structure	Rigid	Collapsible
Lumen diameter	Narrow but changes depending on the beating of the heart^{(5, 6)}	Wide
Movement of blood	Spurty	Sluggish
Oxygen level	High	Low
Carbon dioxide level	Low	High
Muscle contraction	Present	Absent
Blood flow pathway	Distinct	Indistinguishable because veins have many interconnections
What happens if the flow of blood is stopped?	The artery will still remain open	The vein will collapse right away
Time of death	The artery empties up at the time of death	The veins are filled up at the time of death
Diseases	Stroke Atherosclerosis Carotid artery disease Peripheral artery disease Coronary artery disease	Deep vein thrombosis Pulmonary embolism Varicose veins Chronic venous insufficiency ^{(8, 9, and 10)}

Conclusion

Arteries and veins have similarities and differences. One thing is for sure though, they are vital parts of the circulatory system. These two structures are responsible for carrying blood to different parts of the body. The arteries carry oxygenated blood from the heart to different parts of the body with the exception of pulmonary artery.

On the other hand, deoxygenated blood is carried out by the veins from various parts of the body to the heart where it will be supplied with oxygen with the exception of the pulmonary veins. The process goes on and on.

The heart, arteries, and veins are the three essential components of the circulatory system. Any problems in the veins and arteries can significantly affect the circulatory system. Which is why it is important to maintain a healthy lifestyle to prevent circulatory problems. ^{(1, 6, and 9)}

References

https://www.sharecare.com/health/circulatory-system-health/what-difference-between-an-artery-and-a-vein
https://www.healthline.com/health/artery-vs-vein
https://microbiologyinfo.com/difference-between-arteries-and-veins/
https://www.mytutor.co.uk/answers/1766/GCSE/Biology/What-is-the-difference-between-an-artery-and-a-vein/
http://microbiologynotes.com/differences-between-artery-and-vein/
https://biodifferences.com/difference-between-arteries-and-veins.html
https://www.britannica.com/story/whats-the-difference-between-veins-and-arteries
https://www.bioexplorer.net/differences-between-arteries-and-veins.html/
https://www.diffen.com/difference/Arteries_vs_Veins
http://www.differencebetween.net/science/health/difference-between-artery-and-vein/