Po2 (mm Hg) Oxyhemoglobin dissociation at various temperatures

Figure 19.40

The amount of oxygen released from oxyhemoglobin increases as the blood temperature increases.

Carbon Dioxide Transport

Blood flowing through capillaries gains carbon dioxide because the tissues have a high PCO2. This carbon dioxide is transported to the lungs in one of three forms: as carbon dioxide dissolved in plasma, as part of a compound formed by bonding to hemoglobin, or as part of a bicarbonate ion (fig. 19.41).

The amount of carbon dioxide that dissolves in plasma is determined by its partial pressure. The higher the PCO2 of the tissues, the more carbon dioxide will go into solution. However, only about 7% of the carbon dioxide is transported in this form.

Unlike oxygen, which combines with the iron atoms of hemoglobin molecules, carbon dioxide bonds with the amino groups (—NH2) of these molecules. Consequently, oxygen and carbon dioxide do not directly

Tissue cell

Tissue cell

in plasma

Blood ' flow from systemic arteriole hemoglobin to form carbaminohemoglobin

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Essentials of Human Physiology

Essentials of Human Physiology

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