Veins in human body


Veins are the blood vessels that carry deoxygenated blood away from the various body parts towards the hearts for oxygenation of blood. Veins are mostly flexible as they have to bear pressure of blood. Veins consist of three layers that differ due to its composition that is different for every layer. Vein function is actually very  much important in human body. As soon as blood is propelled to all body parts and tissue have received  their oxygen requirement blood is having lower levels of oxygen in it, so it is directed back to the heart for oxygenation so that tissues might be able to fulfill its oxygen necessity. Veins differ in its length, longest vein of the human body is the vein that is present in the lower limb is the great saphenous vein that is present in the medial side of leg and thigh. It is originating from foot and reaches the upper part of thigh afterwards gave supply to groin. Umbilical vein is established only during fetal life. In fetal life its purpose is reverse to other veins  of the body, it carries oxygenated blood instead of de-oxygenated blood from the placenta. In a week later to birth this vein is disintegrated, its place is occupied by  a fibrous thread like structures .  Compression  applied by  blood to  this vein is mostly  20 mm Hg in normal conditions. Certain diseases that are associated to new born this vein will act as a site specialized for transporting blood. Anatomy of veins will show its construction. Veins are prepared up of three layers as:

  • Outer layer made up of connective tissue and collagen fiber collectively.
  • Middle layer of vein is made up of smooth and elastic muscles.
  • The Inner most layers are made up of endothelium layer.

These layers also contain its name like tunica externa, tunica media and tunica intima respectively. A special feature  of vein is that they comprise of  valves  which facilitates the unidirectional flow of blood. Any problem with these valves might cause serious problem like pooling and edema in which legs become swollen.

Human body veins are working actively to transport blood back to the heart. There are 4 main types of veins in the human body that are pulmonary vein; these veins are related to respiration it means that they will carry oxygenated blood from the lungs to the heart. In grown-up humans this vein is performing contrary to other reason is that this vein will carry oxygenated blood is that lungs contain large mount f O2 in it which penetrates in the blood present there. Other is systematic vein that carries de-oxygenated blood from all body parts except the lungs and carry it to the heart. Veins that are apparent and profound  as term demonstrates they are existing, nearby to skin and away from skin correspondingly. Veins and arteries are actively involved in transport of de-oxygenated and oxygenated blood respectively from different parts of the body towards the heart. Circulatory system veins are complex  and are involved in circulation of oxygen deficient blood from different body parts and tissues and carry it to heart for making it oxygen rich.

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