Tunica media
Tunica media
Tunica media (pronounced: too-ni-ka me-di-a) is the middle layer of an artery or vein that is made up of smooth muscle and elastic fibers. This layer is responsible for maintaining blood pressure and circulation through the contraction and relaxation of the smooth muscle.
Etymology
The term "tunica media" is derived from Latin, where "tunica" means "coat" or "layer", and "media" means "middle". Thus, the term literally translates to "middle layer".
Structure
The Tunica media is sandwiched between the Tunica intima (the innermost layer of a blood vessel) and the Tunica externa (the outermost layer of a blood vessel). It is composed primarily of Smooth muscle cells and Elastic fibers, which allow the blood vessel to expand or contract in response to changes in blood pressure and volume.
Function
The primary function of the Tunica media is to regulate the diameter of a blood vessel, which in turn controls blood pressure and flow. The smooth muscle cells within the tunica media can contract, reducing the diameter of the blood vessel (vasoconstriction), or relax, increasing the diameter (vasodilation). This process is regulated by the Autonomic nervous system.
Related Terms
- Artery - A blood vessel that carries blood away from the heart. The tunica media in arteries is generally thicker than in veins due to the higher pressure of blood flow.
- Vein - A blood vessel that carries blood towards the heart. The tunica media in veins is thinner than in arteries.
- Vasoconstriction - The constriction of blood vessels, which increases blood pressure.
- Vasodilation - The dilation of blood vessels, which decreases blood pressure.
External links
- Medical encyclopedia article on Tunica media
- Wikipedia's article - Tunica media
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