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Difference Between Arteries and Veins

Difference Between arteries and veins are based on physical appearance and physiological functions.

Before we go into their differences lets us see the details of both blood vessels.

Arteries and veins are the pipe like vessels which carry blood in the body.

These are two similar yet different types of blood vessels forming the parts of the circulatory system.

In general, arteries carry away the blood pumped by the heart during systole.

While veins carry blood from the periphery of the body back to the heart.

From the heart, arteries start from aorta which branches out as arterioles.

These arterioles further branch out into capillaries.

These capillaries are so minute and pass in between cells and deeper most parts of tissues. Thus they supply the blood containing oxygen and nutrients to each and every cell and tissues.

As seen in the image above, these capillaries extend to converge into veins. They collect the waste and carbon dioxide from the cells and tissue surroundings to bring into the blood for excretion.

These capillaries then converge to form few venules which are bit bigger in size.

These venules further converge to form veins.

These veins further form superior and inferior vena-cava which pour the collected impure blood into the heart which is the main body organs of the circulatory system.

Thus arteries carry pure blood from the heart to the tissues while the veins return impure blood. But interestingly, there are few exceptions for this rule.

A pulmonary vein brings pure oxygenated blood from lungs into the heart.

While a pulmonary artery carries impure blood (carbonated) from the heart to the lungs, so these two are different from the rest of the blood veins and arteries only in terms of the function.

Besides, there are also anatomical structural differences in between them. These differences are meant to keep them safe, perform their function efficiently and also to minimize the workload on the heart. Further, the energy requirement of the body to circulate the blood is minimized.

Anatomy and structure of arteries and veins.

Arteries: Arteries are thickly walled and deeply located in the body. They are also highly elastic due to circular and oblique muscles in their walls. This elasticity helps to convey the pulse from the heart until the blood reaches the cells and tissues. The blood in the arteries flows due to the pressure from the heart contraction. Hence, you can notice pulse in the arteries but not in veins. Even a physician checks your pulse rate either by holding the arteries of the wrists or carotid artery in the neck.

The blood in arteries is reddish brown and enriched with oxygen and nutrients.

Veins: These are thin-walled blood vessels located superficially in the body. Hence, you can see dark-colored veins below the skin in the arms, hands, thighs, etc. The blood flows in them under the influence of capillary action. In humans, this blood flows against the gravitation force. So to prevent backflow, there are valves in the inner walls. These valves close down when the blood tends to flow downwards. Hence, the blood always moves in one direction in veins in-spite of lack of pulse.

The blood in the veins is bluish red and has a high concentration of carbon dioxide, urea and other excretory waste.

Difference Between Arteries and Veins in tabular form

Arteries receive blood due to pressure from the heart while veins do not have that pressure. So the differences are as

Sl.No	Characters	Arteries	Veins
1	Blood	They carry pure blood rich in nutrients	They carry impure blood rich in waste of the body.
2	Wall thickness	Arteries have thicker wall (more tissue)	The veins have thin walls (less tissue)
3	Strength	Arterial walls have more strength, when cut remain open	Veins are comparatively delicate. When cut they collapse
4	Stretch /distensible	Arteries are not distensible	Veins are distensible, So they can accommodate more blood.
5	Body location	They are deep seated in the body.	They are peripherally loacted in the body. Hence we can see blood vessels in the back of hands, on face, legs etc.
6	Blood flow	Blood flows by pulsatile manner corresponding to heart beat.	No pulse, blood flows uniforms
7	Flow pressure	Blood flows due to pumping pressure of heart. So pressure is high.	Blood flows due to capillary action of the veins. Pressure is low comparatively
8	Oxygen level	Oxygen levels is quite high in arterial blood	Oxygen level is low comparatively
9	Carbon-dioxide level	CO2 level is low in arterial blood	CO2 level is high in venous blood,
10	Flow direction	From heart to the tissues	From tissue to the heart.
11	Blood volume	Approximately 1/3rd of whole body blood is present in arteries	2/3rd of whole body blood is present in veins
12	Appearance Color	They are dark reddish color	They are bluish red color.
13	Valves	There are no valves in the artery vessels.	There are valves in the veins allowing blood to flow in upward direction.
14	Diseases	Arteries are susceptible to diseases like angina pectoris, atherosclerosis	Less susceptible to diseases and includes diseases like varicose veins.
15	Gravitational force	Not affected by gravity to a large extent	Can be affected by gravity and hence chances of orthostatic hypotension

Thickness: As seen in the differences above, arteries have thick walls as they have to bear the systolic pressure. Also, they have more muscle mass in the walls to propagate the pulse further due to elasticity. This helps the blood move fast in the vessel to the tissues. Hence we can measure heart pulse from the wrist artery. A further thick wall may minimize the chances of oxygen and nutrients to diffuse to the surroundings.

Body location: Their deep-seated or location in the body may also be to prevent damage to them in case of injury to the body. As their damage can destroy the organ receiving the blood faster. But for veins, there is another alternate called lymph vessels which also carry waste from tissues. So damage can to them can be less severe. The only condition is there should be no hemorrhage.

Pressure: Pressure in arteries is more than in veins.

Valves: Help in preventing the blood in backward flow as veins rely on capillary action. Since there is a change in gravitational pressure when sitting and standing up, their chances of varying inflow pressure. So valves prevent backflow of blood in veins. This is not required in arteries.

Color: The arteries are dark reddish due to oxygenated blood. While for veins, bluish red is due to oxygenated blood.

Diseases: Arteries are thick and carry nutrition. So, nutrition born disease occurs due to the accumulation of fat. While for veins it is rare but occurs due to obstruction or physical damage to them.

Thus arteries and veins have functional and structural differences to suit the needs of the body.