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Question

Difficulty: MediumHuman Anatomy and Body Systems

After blood absorbs oxygen across the alveolar membranes in the lungs, which blood vessels carry this oxygenated blood directly into the left atrium of the heart?

  1. A
    Pulmonary arteries
  2. B
    Carotid arteries
  3. Pulmonary veinsAnswer
  4. D
    Jugular veins

Answer

Pulmonary veins
Pulmonary veins are the vessels that return newly oxygenated blood from the lungs directly into the left atrium of the heart, representing a key exception where veins transport oxygen-rich blood.

Step-by-Step Solution

1
Identify the direction of blood flow relative to the heart
Vessels carrying blood back toward the heart are classified as veins.
By anatomical definition, arteries always carry blood away from the heart, while veins return blood toward the heart.
2
Determine the oxygenation state and specific circuit involved
The pulmonary circuit is an exception to the general rule that veins carry deoxygenated blood; the pulmonary veins carry oxygen-rich blood from the lungs to the left atrium.
Blood that has just undergone gas exchange in the lungs is oxygen-rich and must enter the left side of the heart to be pumped to the rest of the body.

Key Concept

Pulmonary circulation and vessel classification exceptions
Estimated Time:45s
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Topics

Human Anatomy and Body Systems

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