BIOL 142 Study Guide - Midterm Guide: Tunica Media, Pulmonary Artery, Elastic Fiber
4 Jul 2018
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Muscular Arteries
The diameter of muscular arteries ranges from that of a little finger to that of a pencil.
Proportionately, muscular arteries have the thickest tunica media of all vessels. Their
tunica media contains relatively more smooth muscle and less elastic tissue than do
elastic arteries. For this reason, they are more active in vasoconstriction and less
capable of stretching. In muscular arteries, however, there is an elastic membrane of
each face of the tunica media.
Composition of Muscular Arteries
The smallest of the arteries. Have a lumen diameter ranging from 0.3 mm down to 10
um. Larger arterioles have all three tunics, but their tunica media is chiefly smooth
muscle with a few scattered elastic fibers. Smaller arterioles, which lead into the
capillary beds, are little more than a single layer of smooth muscle cells spiraling around
the endothelial lining.
Arterioles
Blood flow into the capillary beds is determined by arteriolar diameter, which varies in
response to changing neural, hormonal and local chemical influences.
How does the diameter of arterioles determine blood flow?
Changing diameter changes resistance to blood flow. When arterioles constrict, the
tissues served are highly bypassed. When arterioles dilate, the blood flow into the local
capillaries increases dramatically.
Why are arterioles called resistance vessels?
- Active in vasoconstriction
- Assist in maintaining blood pressure.
Function of Muscular Arteries
- Conduction arteries
- Maintain continuous flow of blood away from the heart
Function of Elastic Arteries
- Change in diameter for vasoconstriction and vasodilation to control blood flow to
capillaries
- Control blood flow to capillary networks
Function of Arterioles
Most of the "named" arteries of the body.
Location of Muscular Arteries
- Aorta
- Pulmonary arteries
Location of Elastic Arteries
...
Location of Arterioles
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Document Summary
The diameter of muscular arteries ranges from that of a little finger to that of a pencil. Proportionately, muscular arteries have the thickest tunica media of all vessels. Their tunica media contains relatively more smooth muscle and less elastic tissue than do elastic arteries. For this reason, they are more active in vasoconstriction and less capable of stretching. In muscular arteries, however, there is an elastic membrane of each face of the tunica media. Have a lumen diameter ranging from 0. 3 mm down to 10 um. Larger arterioles have all three tunics, but their tunica media is chiefly smooth muscle with a few scattered elastic fibers. Smaller arterioles, which lead into the capillary beds, are little more than a single layer of smooth muscle cells spiraling around the endothelial lining. Blood flow into the capillary beds is determined by arteriolar diameter, which varies in response to changing neural, hormonal and local chemical influences.
