Oxygen is released into body cells from the capillaries , the tiniest blood vessels where exchange of gases and nutrients with tissues takes place.

Quick Scoop

  • Capillaries form a fine network that surrounds body cells. Their walls are extremely thin, allowing oxygen to diffuse out of the blood and into the cells.
  • As blood flows through these capillaries, it drops off oxygen and nutrients and picks up carbon dioxide and other wastes before moving into small veins (venules).

So, to answer clearly: in the human body, oxygen is released into body cells in the capillaries, not in the larger arteries or veins.

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