BIOL 142 Study Guide - Quiz Guide: Tunica Intima, Simple Squamous Epithelium, Loose Connective Tissue
4 Jul 2018
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Carry blood away from the heart. They are said to "branch," "diverge," or "fork" as they
form smaller and smaller divisions.
Arteries
1. Tunica intima (innermost)
2. Tunica media (middle)
3. Tunica externa (outermost)
Three Layers of Blood Vessel Walls
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Tunica Intima
Innermost tunic that comes into intimate contact with the blood in the lumen. The tunica
intima contains the endothelium, the simple squamous epithelium that lines the lumen of
all vessels. The endothelium is continuous with the endocardial lining of the heart, and
its flat cells fit closely together, forming a slick surface that minimizes friction as blood
moves through the lumen.
Tunica Intima
In vessels larger than 1 mm in diameter, a subendothelial layer, consisting of a
basement membrane and loose connective tissue, supports the endothelium.
Subendothelial Layer
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Subendothelial Layer
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Tunica Media
The middle tunic that is mostly circularly arranged smooth muscle cells and sheets of
elastin. The activity of the smooth muscle is regulated by sympathetic vasomotor nerve
fibers of the autonomic nervous system and a whole battery of chemicals. Depending
on the body's need at any given moment, regulation causes either vasoconstriction or
vasodilation.
Tunica Media
The activities of the tunic media are critical in regulating circulatory dynamics because
small changes in vessel diameter greatly influence blood flow and blood pressure.
Generally, the tunic media is the bulkiest later in arteries, which bear the chief
responsibility for maintaining blood pressure and circulation.
Function of the Tunica Media
Lumen diameter decreases as the smooth muscle contracts
Vasoconstriction
Lumen diameter increases as the smooth muscle relaxes
Vasodilation
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Tunica Externa
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find more resources at oneclass.com
Document Summary
They are said to branch, diverge, or fork as they form smaller and smaller divisions. Arteries: tunica intima (innermost, tunica media (middle, tunica externa (outermost) Innermost tunic that comes into intimate contact with the blood in the lumen. The tunica intima contains the endothelium, the simple squamous epithelium that lines the lumen of all vessels. The endothelium is continuous with the endocardial lining of the heart, and its flat cells fit closely together, forming a slick surface that minimizes friction as blood moves through the lumen. In vessels larger than 1 mm in diameter, a subendothelial layer, consisting of a basement membrane and loose connective tissue, supports the endothelium. The middle tunic that is mostly circularly arranged smooth muscle cells and sheets of elastin. The activity of the smooth muscle is regulated by sympathetic vasomotor nerve fibers of the autonomic nervous system and a whole battery of chemicals.
