1. Review textbook sections on inspiration and expiration.
Breathing involves the movement of air from outside the body through the bronchial tree and into the alveoli and the reversal of this air movement. These movements are caused by changes in the size of the thoracic cavity that result from skeletal muscle contractions and from the elastic recoil of stretched tissues.
The volumes of air that move in and out of the lungs during various phases of breathing are called respiratory air volumes and capacities. These volumes can be measured by using an instrument called a spirometer. However, the values obtained vary with a person's age, sex, height, and weight. Various respiratory capacities can be calculated by combining two or more of the respiratory volumes.
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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.