Blood vessel - Definition and Overview

The blood vessels are part of the circulatory system and function to transport blood throughout the body.

Types

• Arteries
  • Aorta (the largest artery, carries blood out of the heart)
• Arterioles
• Capillaries (the smallest blood vessels)
• Venules
• Veins
  • Venae cavae (the 2 largest veins, carry blood into the heart)

Glossary

• Vasoconstriction is the constriction of blood vessels (narrowing, becoming smaller in cross-sectional area) by contracting the vascular smooth muscle in the vessel walls.
  • A vasoconstrictor is any drug that acts to constrict blood vessels. Many vasoconstrictors act on specific receptors, such as vasopressin receptors or adrenoreceptors.

Vasoconstrictors are used to increase blood pressure or to reduce local blood flow.

• Vasodilation is the dilation of blood vessels (widening) by relaxing the smooth muscle in the vessel walls.
  • Vasodilators are drugs that work to dilate blood vessels.

Vasodilation and vasoconstriction are used antagonistically as a method of thermoregulation in homeotherms.

See also

• anatomy
• human anatomy
• cardiovascular system
• vascular resistance
• endothelium
• endothelium-derived relaxing factor
• anastomosis
• atherosclerosis
• vasculitis (inflammation of blood vessels)
• angiogenesis (formation of blood vessels)