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What is the difference between Vein and Artery?

We explain the difference between vein and artery with structure and function of artery and vein. In addition: comparison chart to better understand.

What is the difference between Vein and Artery?

Veins and arteries are often confused with each other and even used interchangeably. However, it is important to know that each of these has its own characteristics and functions, so knowing the differences between between Vein and Artery is important.

Along with the lymphatic vessels, the blood and the heart; veins and arteries make up the circulatory system. The human body has more veins than arteries. They also contain up to 70% of the total blood volume in a person.

difference between vein and artery

What are Veins?

Veins are the high-capacity blood vessels that carry deoxygenated blood from the body’s capillaries to the heart. This blood that is transported is reoxygenated when it passes through the lungs.

Veins are generally more irregular in shape and larger than the corresponding arteries, containing approximately 70% of the total volume of blood. In contrast, they are thinner-walled so they collapse more quickly when pressed.

There are also veins, like the pulmonary veins, that contain oxygenated blood that is carried to the heart and then to the rest of the body thanks to the umbilical veins and the aorta artery.

In the pulmonary or minor circulation, the arteries carry oxygen-depleted blood from the heart to the lungs, and the pulmonary veins carry oxygenated blood from the lungs to the heart.

Both the blood samples and the supply of medicines and nutrients is done through the veins.

Veins are generally associated with arteries of the same name.

So, A vein is a tube responsible for the transportation of blood from the blood capillaries to the heart. Normally the veins carry carbon dioxide (CO 2) and deoxygenated blood that returns to the heart. However, there are some veins that carry oxygenated blood, and even when transporting blood back to the heart, the pressure in them decreases.

difference between vein and artery

It is common to find veins at a more superficial level, which can be observed and palpated, mainly in the arms, wrists and hands.

What are Arteries?

The arteries are the vessels that carry oxygenated blood from the heart to the capillaries in the body.

Arteries are thick-walled blood vessels than veins, so they are firmer . They conduct blood that has been previously oxygenated in the lungs from the heart to the tissues with increased pressure during systole.

The further away the arteries are from the heart, their layer loses its elastic fibers, and these go from being elastic arteries to being known as muscular or distribution arteries .

As the heart pumps blood discontinuously, after an artery is distended by the flow carried by ventricular systole, its elastic nature creates a contraction of its wall, this is known as diastolic pressure. This process allows the uninterrupted flow of blood to the tissues, which does not occur in ventricular diastole.

The primary functions of the arteries are to deliver oxygen and nutrients to all cells, remove both carbon dioxide and waste products, and maintain physiological pH.

The arteries, having the highest pressure in the circulatory system, are the ones that produce the pulse where cardiac activity is reflected.

So, It is a conduit whose main function is to transport blood from the heart to the rest of the body of a living being. Specifically, the blood carried by the arteries is oxygenated, which is why it tends to be a lighter or brighter red color.

Arteries

The fact that the function of the arteries is to transport blood directly from the heart, implies that the blood pressure in them is higher. Blood pressure varies depending on cardiac contraction, which is called systolic pressure and, at a minimum, diastolic pressure. The walls of the arteries are very elastic and resistant.

Structure and function of the Veins

The structure of the veins is similar to the structure of the arteries, but the muscular layer is weaker , it does not maintain a tone as firm as in the arteries and they do not have the same contraction capacity. Due to this lower tone the veins are much more flexible. They can swell when full of blood and collapse when empty.

Another very prominent structural difference is the existence of valves inside that make it difficult for the blood to flow back ; Without the existence of these venous valves, the effect of gravity would cause blood to easily accumulate in the lower part of the body.

Veins collect blood after it has passed through tissues. During this step, the cells take in the oxygen (O 2 ) they need and leave carbon dioxide (CO 2 ) in the blood and carry it to the heart and from here the blood leaves to the lungs. In the lungs, CO 2 is expelled into the air and the blood takes in oxygen again.

The heart-lung-heart circulation is known as the minor circulatory system and here the transport in veins and arteries is the other way around. The arteries carry blood rich in CO 2 and poor in O 2 from the heart to the lungs (that which has reached the heart through the veins); in the lungs a gas exchange takes place between the blood and the air, expelling CO 2 and taking O 2 . This oxygenated blood returns to the heart through the pulmonary veins and from the heart is distributed to the body through the arteries.

A curious difference is that the location of the arteries is very similar in all people . However, the location of the veins has a much greater variability.

Veins are the blood vessels used when someone needs to inject drugs directly into the bloodstream or for parenteral feeding (administration of nutrients and fluids intravenously).

In blood extractions, veins are also used and not arteries due to their lesser contraction, which makes puncture easier, and their better visualization in the outer layers of the skin.

Structure and function of the Arteries

The tissue of the arteries is designed to facilitate rapid and effective blood transport to all tissues of the body. The arteries carry the oxygen taken in the lungs to the cells and that they require for their function.

The outer layers of the arteries are made up of connective tissue , the middle layers are made up of smooth muscles, and the innermost layers, in contact with blood, are made up of endothelial tissue.

The muscle tissue shrinks or expands to meet the needs of blood from every part of the body at all times. It contracts in the areas that need the least blood and dilates in the areas with the most needs .

For example, when it is cold, more blood is drawn to the skin to keep the outermost parts of the body warm that can be affected more quickly by external cold, there is generalized peripheral vasodilation and internal vasoconstriction to divert more blood flow to the outside.

When we take a pulse by skin palpation, for example on the back of the wrist, what is really felt is the expansion and contraction of this tissue caused by each heart beat, not the heart beat itself .

The endothelial tissue structure of the inner layers of the arteries leave a very smooth surface that facilitates the passage of blood and offers very little resistance to flow. These layers are those that are damaged in some of the main causes of death in man: cardiovascular accidents.

difference between vein and arteryKey differences between Vein and Artery

  • A vein is a conduit responsible for transporting blood from the body to the heart, otherwise the artery that is responsible for transporting blood from the heart to the rest of the body.
  • Almost all veins carry deoxygenated blood and carbon dioxide, except for umbilical and pulmonary veins. The arteries carry oxygenated blood throughout the body.
  • In the human body there is less presence of veins than arteries.
  • The veins are slightly visible in the skin, and the arteries are deeper so they cannot be easily seen
  • The blood transported by the veins is darker due to carbon dioxide, in the case of the arteries, the blood is clearer and brighter due to oxygen and lack of carbon dioxide.
  • The veins work with lower blood pressure, the pressure of the arteries being much higher.

network of the blood vessels

Difference between Vein and Artery by Comparative chart

Vein and Artery
Vein Artery
What are they? Veins are blood vessels that carry blood from capillaries (blood vessels) to the heart. In the same way, arteries are blood vessels that carry blood from the heart to the capillaries in the body.
Structure Scarce muscular layer, its walls are thinner and more superficial. Thicker, stronger and more flexible muscle layer.
Features Conduct deoxygenated blood through the body. Transport oxygenated blood.
Type of blood they carry Almost all veins carry deoxygenated blood, that is, without oxygen. As for the arteries, they carry oxygenated blood throughout the body.
Characteristics of blood The blood they carry is dark in color because it has no oxygen. The blood that circulates in them is of a lighter color because it is oxygenated.
Graphic representation The color blue is used to avoid confusion with the arteries. They are represented by the color red.
What other substances do they carry? Carbon dioxide and metabolic waste that is eliminated as it passes through the lungs, kidneys and liver. Only oxygen.
What direction do they lead? Veins carry blood from capillaries to the heart. The arteries on the other hand, direct blood flow from the heart to the capillaries in the tissues.
Internal valves Present. Missing.
Examples
  • Jugular.
  • Upper and lower cava.
  • Coronary.
  • Subclavian.
  • Aorta.
  • Pulmonary.
  • Carotid.
  • Subclavian.
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