Multiple choice

Tiny, thin-walled blood vessels where the blood and body cells exchange substances are called

  1. atria

  2. ventricles

  3. capillaries

  4. single loop

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Capillaries are the smallest blood vessels in the body. Their thin walls allow for the efficient exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues.