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Difficulty: EasyHuman Anatomy and Body Systems

In the human circulatory system, systemic veins carry blood back to the heart under relatively low pressure. Which anatomical feature inside these veins prevents blood from flowing backward?

  1. A
    Thick elastic walls
  2. One-way valvesAnswer
  3. C
    High-resistance muscular sphincters
  4. D
    Rigid cartilaginous rings

Answer

One-way valves prevent the backflow of blood in systemic veins.
Because systemic veins operate under low pressure and often transport blood upward against gravity, they contain internal one-way valves. These valves open as blood moves toward the heart and close tightly to prevent backward flow.

Step-by-Step Solution

1
Identify the physiological conditions governing venous blood return.
Blood in systemic veins travels under low hydrostatic pressure and frequently moves upward against the pull of gravity.
Recognizing the low-pressure environment highlights why a mechanical barrier is needed to maintain forward movement.
2
Determine the specific anatomical structure in veins responsible for maintaining unidirectional flow.
Veins possess one-way flap valves that open toward the heart and snap shut if blood begins to reverse direction.
These valves ensure that blood continues advancing toward the right atrium without pooling in the lower extremities.

Key Concept

Venous valve function in unidirectional blood flow
Estimated Time:45s
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Topics

Human Anatomy and Body Systems

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