Question

Where does carbon-dioxide enter the blood?

Answer 1

some of the carbon dioxide is transported dissolved in the plasma. Some carbon dioxide is transported as carbaminohemoglobin.As blood flows through the tissues, carbon dioxide diffuses into red blood cells, where it is converted into bicarbonate.

Answer 2

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Virtually every molecule of carbon dioxide produced by metabolism must exist in the free form as it enters blood in the tissues and leaves capillaries in the lung. Between these two events, most carbon dioxide is transported as bicarbonate or carbamate.