II. b. DIGESTIVE SYSTEM
The digestive system includes the alimentary canal or gastrointestinal tract, a
tubular, muscle-lined passageway that extends from the mouth to the anus. The muscles
in the walls of the passage way are responsible for peristalsis. You will view the regions
along this tube that are specialized for various activities of the digestive system.
Path of Air
Since the paths of air and food are closely associated, let's also trace the path of
air through the head and neck. When the mouth is closed, air enters the body through the
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