Veins of the Human Body

At human body veins they are blood vessels that are part of the body's circulatory system and branch throughout our body.

The main function of the veins is to transport blood, poor in oxygen and filled with waste, from the capillaries to the heart. The vessels that carry blood out of the heart are called arteries.

Thus, note that blood vessels are classified as: blood arteries, veins and capillaries. They differ from each other both by the function they perform and by the thickness of their walls.

Anatomy of the Human Body's Veins

Veins of the Human Body — vein structure

Veins are cylindrical tubes formed by venous valves that impede the reverse flow of blood.

They have the ability to contract and expand their size according to the amount of blood made available, so it serves as a reservoir.

To control the flow of blood correctly, the veins have valves that help maintain blood pressure as well as prevent the accumulation of blood.

The vein wall is formed by three layers, which are:

Inner tunic: is formed by connective tissue;

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Middle tunic: it is the most resistant layer and is formed by muscle tissue and elastic tissue;
Outer tunic: also known as tunica adventitia is formed by flexible connective tissue.

Main Veins of the Human Body

See below the main veins that are part of the human body.

pulmonary vein

These veins carry oxygen-rich blood from the lungs to the left atrium of the heart.

There are four pulmonary veins, two for each lung: an upper right and an inferior one, in addition to an upper and lower left.

Vena cava

The vena cava is considered the main vein in the body, as it is responsible for carrying blood from the head, upper limbs, lower limbs and abdomen back to the heart. Therefore, it is divided into superior vena cava and inferior vena cava.

They are also known to be part of the systemic circulation (or grand circulation).

The vena cava is used as part of the treatment of thrombosis in people who are at risk for the disease.

door vein

The portal vein is part of the circulatory system and plays an extremely important role, as it is through it that the blood that comes from the intestine, stomach and esophagus passes to reach the liver.

Thus, we have the portal vein system, which is then formed by several veins that form numerous branches inside the liver.

Femoral vein

The femoral vein is located in the lower limbs and follows the entire femoral artery. They are divided into two groups: deep, which accompany the main arteries, and superficial, which are in the subcutaneous tissue.

This vein runs through the entire leg and works together with other veins that promote the circulation and drainage of blood from the muscles. It is through the femoral vein that the blood flow from the leg passes.

Iliac veins

The iliac veins are located in the abdomen region and accompany the common iliac artery.

The iliac veins are classified into two groups (internal and external) and, when together, form the inferior vena cava.

A common anomaly that occurs in this vein is May-Thurner syndrome, which consists of compression of the vein by the artery. After diagnosis, a stent (a kind of mesh) can be inserted that decompresses and allows for correct blood flow.

jugular vein

The jugular vein is located in the neck and its function is to transport venous blood (rich in carbon dioxide and poor in oxygen) from the skull to parts of the body.

In the human body, two pairs are found, one internal and one external, on each side of the neck.

saphenous vein

The saphenous veins are the main veins in the venous system, as they are responsible for transporting blood from the upper limbs to the lower limbs of the body.

They are located on the lower limbs.

Diseases caused by lack of circulation in the veins

Some diseases can be related to the veins and circulation. Here are some examples.

Varicose veins

Varicose veins are dilated veins that appear in the lower limbs causing pain, swelling, deformity and loss of sensation. Although it is more common in women, men also have varicose veins.

Varicose ulcers are characterized by accumulation of venous blood, lack of oxygenation, increased pressure, and accumulation of toxins.

Phlebitis

Phlebitis, also called venous thrombosis, is characterized by inflammation that occurs in the wall of the veins, causing swelling, pain and a feeling of heaviness in the legs.

It is noteworthy that there are two types of phlebitis: superficial phlebitis, characterized by visible veins; and deep phlebitis, marked by deeper veins.

Curiosities about the veins of the human body

Veins, arteries and capillaries are 97 thousand kilometers throughout our body.
The study of veins and blood vessel treatments is called Phlebology.
The vein has thinner walls than the arteries as they suffer less pressure.
The diameter of the veins can vary, that is, some are less than 1 mm (thin veins), and others can reach up to 10 mm (thick veins).

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