Po2 (mm Hg) Oxyhemoglobin dissociation at 38°C

Figure 19.38

The amount of oxygen released from oxyhemoglobin increases as the Pco2 increases.

accompanied by increased oxygen use increases the PCo2, decreases the pH, and raises the local temperature. At the same time, less-active cells receive less oxygen.

Carbon monoxide (CO) is a toxic gas produced in gasoline engines and some stoves as a result of incomplete combustion of fuels, as the chapter opener describes. It is also a component of tobacco smoke. Carbon monoxide is toxic because it combines with hemoglobin many times more effectively than does oxygen and therefore does not readily dissociate from hemoglobin. Thus, when a person breathes carbon monoxide, less hemoglobin is available for oxygen transport, and the body cells soon begin to suffer from oxygen deficiency. The effects of carbon monoxide on hemoglobin may be responsible for the lower average birth weights of infants born to women who smoked while pregnant.

Treatment for carbon monoxide poisoning is to administer oxygen in high concentration to replace some of the carbon monoxide bound to hemoglobin molecules. Carbon dioxide is usually administered simultaneously to stimulate the respiratory center, which, in turn, increases breathing rate. Rapid breathing helps reduce the concentration of carbon monoxide in the alveoli.

How is oxygen transported from the lungs to body cells?

What factors affect the release of oxygen from oxyhemoglobin?

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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