Difference Between Artery, Vein, and Capillary

Blood vessels are the channels inside the body that carry blood from and to the heart and other parts. The body has various areas where the vessels carry blood, so it is of 3 types; artery, vein, and capillary. The blood vessel which carries blood away from the heart is the artery. A vein is the smallest blood vessel that connects arteries and veins. 

Although the arteries, veins, and capillaries carry blood, they have many differences based on their location, size of the wall, blood type they carry, types, the direction of blood flow, presence or absence of valves, and the type of tissues.

Difference Between Artery and Vein

Arteries carry oxygenated blood away from the heart except for pulmonary arteries, which carry deoxygenated blood. Whereas veins carry deoxygenated blood towards the heart except for pulmonary veins that carry deoxygenated. Likewise, the arteries lie deep under the tissues, and veins are superficial (under the skin).

Properties	Artery	Vein
Direction of blood flow	Arteries carry blood away from the heart.	Veins carry blood toward the heart.
The type of blood they carry	Carries oxygenated blood except for pulmonary arteries.	Carries deoxygenated blood except for pulmonary veins.
Functions	Carry blood to the body organs.	Carry blood to the heart.
The thickness of the wall	The wall is thick.	The walls are thin.
Lumen	The lumen is narrow.	The lumen is wider.
Tunica Externa	Less developed and weaker.	More developed and stronger.
Tunica Media	It is muscular and consists of more elastic fibers.	It is less muscular and consists of fewer elastic fibers.
Tunica Interna	It has many elastic fibers and collagen.	It has fewer elastic fibers and collagen.
Valve	Only the pulmonary artery has valves.	All the veins have valves for controlling the blood flow.
Tissue	Has a thick layer of muscle tissues.	Has a thin layer of muscle tissues.
Types	Arteries are of three types; elastic, muscular, and arterioles.	Veins are of four kinds; deep veins, superficial veins, pulmonary veins, and systemic veins.
Location	Arteries are rooted deep into the tissues.	Veins are usually found near the skin.
Color	Red in color.	Blue in color.
Blood pressure	The blood pressure is high.	The blood pressure is low.
During death	It empties out at the time of  death.	The veins fill up at the time of death.

Difference Between Artery and Capillary

Arteries carry blood away from the heart, whereas capillaries join arteries and veins. The capillaries are the thinnest blood vessel, and arteries are the thickest blood vessels. Likewise, the arteries are located deep inside the tissues, and capillaries are located superficially just under the skin.

Properties	Artery	Capillary
Function	Artery carries blood from the heart to other body parts.	Capillary joins artery and veins.
The thickness of the wall	It is the thickest blood vessels.	It is the thinnest blood vessel.
Location	Located deep inside the skin.	Located more superficially.
Size	It is the largest blood vessel.	It is the smallest blood vessel.
Muscle Tissue	It is present in large numbers.	It is absent.
Lumen	It is wider than the lumen of the capillary.	Lumen is extremely narrow.
Pressure	The pressure during blood flow is extremely high.	The pressure is low.

Difference Between Vein and Capillary

Although veins and capillaries are located superficially and visible under the skin, the capillaries join the arteries and veins, but veins carry blood to the heart. Also, veins have valves for controlling the transport of blood, but capillaries lack the valves. A detailed difference is given below:

Properties	Vein	Capillary
Thickness of the wall	The vein’s wall is thicker than the capillary wall.	The wall of the capillary is thinner than that of veins.
Valve	The vein has valves to control the transport of blood.	Capillary does not have any valves.
Function	Carries blood towards the heart.	The junction where veins and artery.
The type of blood it carries	Mostly deoxygenated blood.	Both oxygenated and deoxygenated blood.
Branches	There are no branches in veins.	The capillary is highly branched.
Involved in	The veins are involved in the circulatory system.	The capillaries are involved in microcirculation.
Types	Four types; deep veins, superficial veins, pulmonary veins, and systemic veins.	Three types; continuous, fenestrated, and discontinuous or sinusoid.

References:

• Frothingham, S. (2018). Artery vs. Vein: What’s the Difference?. Healthline. Retrieved 2 August 2022, from https://www.healthline.com/health/artery-vs-vein.
• Nicola, S. (2021). What’s the Difference Between Arteries, Veins, and Capillaries?. WebMD. Retrieved 2 August 2022, from https://www.webmd.com/heart/difference-between-arteries-veins-capillaries.
• Blood Vessels: Types, Anatomy, Function & Conditions. Cleveland Clinic. Retrieved 2 August 2022, from https://my.clevelandclinic.org/health/body/21640-blood-vessels.
• Blood Vessels. The Franklin Institute. Retrieved 2 August 2022, from https://www.fi.edu/heart/blood-vessels.