Vein

Veins are blood vessels in humans, and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart. In contrast to veins, arteries carry blood away from the heart.

Vein
The main veins in the human body
Structure of a vein, which consists of three main layers. The outer layer is connective tissue, called tunica adventitia or tunica externa; a middle layer of smooth muscle called the tunica media, and the inner layer lined with endothelial cells called the tunica intima.
Details
SystemCirculatory system
Identifiers
Latinvena
MeSHD014680
TA98A12.0.00.030
A12.3.00.001
TA23904
FMA50723
Anatomical terminology

Veins are less muscular than arteries and are often closer to the skin. There are valves (called pocket valves[1]) in most veins to prevent backflow.


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This article uses material from the Wikipedia article Vein, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.