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Inner layer of blood vessel From Wikipedia, the free encyclopedia
The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (layer) of an artery or vein. It is made up of one layer of endothelial cells (and macrophages in areas of disturbed blood flow),[1][2] and is supported by an internal elastic lamina. The endothelial cells are in direct contact with the blood flow.
This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (May 2015) |
Tunica intima | |
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Details | |
Part of | Wall of blood vessels |
Identifiers | |
Latin | tunica intima |
MeSH | D017539 |
TA98 | A12.0.00.018 |
TA2 | 3922 |
TH | H3.09.02.0.01003 |
FMA | 55589 |
Anatomical terminology |
The three layers of a blood vessel are an inner layer (the tunica intima), a middle layer (the tunica media), and an outer layer (the tunica externa).
In dissection, the inner coat (tunica intima) can be separated from the middle (tunica media) by a little maceration, or it may be stripped off in small pieces; but, because of its friability, it cannot be separated as a complete membrane. It is a fine, transparent, colorless structure which is highly elastic, and, after death, is commonly corrugated into longitudinal wrinkles.
The structure of the tunica intima depends on the blood vessel type.[3]
Elastic arteries – A single layer of endothelial and a supporting layer of elastin-rich collagen. The layer also contains fibroblasts, immune cells and smooth muscle cells.[1]
Muscular arteries – Endothelial cells
Arterioles – A single layer of endothelial cells
Veins – Endothelial cells[3]
The inner coat consists of:
Endothelium had been seen to be simply the boundary between the blood in the lumen and the walls of the vessels. However, endothelium has been shown to release local chemicals called endothelins which are powerful vasoconstrictors.[4] Endothelins help to regulate capillary exchange and alter blood flow by their constriction of the smooth muscle in the walls. Vasoconstriction increases blood pressure, and its overexpression can contribute to hypertension and cardiovascular disease.[5]
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