vein
Sign in to saveA vein () is a blood vessel in the circulatory system of humans and most other animals that carries blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal circulations which carry oxygenated blood to the heart. In the systemic circulation, arteries carry oxygenated blood away from the heart, and veins return deoxygenated blood to the heart, in the deep veins.
AI overview
A vein is a blood vessel that carries blood back toward the heart as part of the circulatory system in humans and other animals. Most veins transport blood that has lost its oxygen as it passed through the body's tissues, though a few exceptions like the pulmonary veins carry oxygen-rich blood instead.
AI-generated from the Wikipedia summary — may contain errors.
Key facts
- Anatomy.Name
- Vein
- Anatomy.Latin
- vena
- Anatomy.Image
- Vein (retouched).svg
- Anatomy.Caption
- Structure of a vein, which consists of three main layers: an outer layer of connective tissue, a middle layer of smooth muscle, and an inner layer lined with endothelium.
- Anatomy.Width
- 200px
- Anatomy.System
- Circulatory system
via Wikipedia infobox
Article
25 sectionsContents
- Structure
- Venous system
- Venous valves
- Circulatory routes
- Microanatomy
- Development
- Function
- Clinical significance
- Venous insufficiency
- Venous thrombosis
- Deep vein thrombosis
- Superficial vein thrombosis
- Portal hypertension
- Phlebitis
- Compression
- Vascular anomalies
- Venous access
- Imaging
- Recognition techniques
- History
- See also
- References
- Bibliography
- Further reading
- External links
A vein () is a blood vessel in the circulatory system of humans and most other animals that carries blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and fetal circulations which carry oxygenated blood to the heart. In the systemic circulation, arteries carry oxygenated blood away from the heart, and veins return deoxygenated blood to the heart, in the deep veins.
There are three sizes of veins: large, medium, and small. Smaller veins are called venules, the smallest of which are called post-capillary venules – microscopic veins that play a major role in microcirculation. Veins are often closer to the skin than arteries.