HISTOLOGY
BLOOD VESSELS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Outer layer
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Fibrous connective tissue Sheath
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Has its own blood vessels on it
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None of the above
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Detailed explanation-1: -Function. The tunica externa provides basic structural support to blood vessels. It prevents vessels from expanding too much from internal blood pressure, particularly arteries. It is also relevant in controlling vascular flow in the lungs.
Detailed explanation-2: -The outermost layer, tunica externa, comprises connective tissue providing protection for the vessel. The tunica media is composed of smooth muscle cells and elastic tissue that is responsible for autoregulation of cerebral blood flow.
Detailed explanation-3: -The tunica adventitia, the outermost layer, is the strongest of the three layers. It is composed of collagenous and elastic fibres. (Collagen is a connective-tissue protein.) The tunica adventitia provides a limiting barrier, protecting the vessel from overexpansion.