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Difficulty: MediumHuman Anatomy and Body Systems

During periods of intense physical exercise, the body redistributes blood flow toward active skeletal muscles and away from digestive organs. Which type of blood vessel possesses the thickest smooth muscle layer relative to its diameter and plays the primary role in regulating this peripheral resistance through vasoconstriction and vasodilation?

  1. A
    Capillaries
  2. ArteriolesAnswer
  3. C
    Large systemic veins
  4. D
    Elastic arteries

Answer

Arterioles are the primary resistance vessels in the circulatory system responsible for regulating blood flow distribution and peripheral resistance.
Arterioles are known as the resistance vessels of the cardiovascular system. Their walls contain a high proportion of smooth muscle innervated by the autonomic nervous system. By constricting or dilating, arterioles directly determine systemic vascular resistance and dynamically direct blood flow to specific tissues depending on physiological demand.

Step-by-Step Solution

1
Identify the structural requirement for regulating blood vessel diameter and flow resistance.
Vessels must contain responsive layers of vascular smooth muscle in their tunica media.
Vasoconstriction and vasodilation require active muscular contraction and relaxation.
2
Evaluate the functional roles of the different blood vessel types in the circulatory system.
Arterioles are specifically adapted with high smooth muscle-to-lumen ratios to modulate systemic vascular resistance.
Large arteries act as pressure dampeners, capillaries facilitate substance exchange, and veins serve as low-pressure volume reservoirs.
3
Determine which vessel class matches the exercise-induced redistribution described in the stem.
Arterioles constrict in visceral organs and dilate in skeletal muscles to redistribute cardiac output.
Arteriolar tone directly dictates local tissue perfusion.

Key Concept

Vascular resistance and tissue perfusion regulation by arterioles
Estimated Time:1m 0s
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Topics

Human Anatomy and Body Systems

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