Module 7 Intro

Module 7—The Digestive and Respiratory Systems

Digestion

Have you ever chewed gum for so long that it dissolved? Digestion starts with the physical mashing of food in your mouth. As well, each organ that comes into contact with snacks or meals secretes a particular enzyme to catalyze the digestion of specific macromolecules. In the case of chewing gum, eventually the enzymes in your saliva will break down the starches in your gum.

The movement of food through the digestive system is dependent on the smooth muscles of the motor system. Peristalsis and sphincters control the movement of food, or chyme, through your system.

Read

Read “Digestion Begins: The Mouth and the Esophagus” on pages 218 and 219 of the textbook.

Try This

TR 1. Mapping the Route from Gums to Bums

Begin creating a flow chart or a diagram that states the first two structures involved in digestion—the mouth and esophagus—the function of the structures, as well as the secretions and functions of the secretions. Throughout this lesson, beginning now, there will be several spots where you will return to your Lesson 2 Assignment to add to your digestive Gums to Bums journey.

Read

Further physical and chemical digestion occurs once food enters the stomach via the esophagus. An empty stomach can look very small, like a sausage. However, it has the capacity to expand to hold a large meal from an all-you-can-eat buffet or, in the case of “The Tsunami,” 54 hot dogs and buns. Read “Storing, Digesting, and Pushing Food: The Stomach” on page 220 of the textbook.

Self-Check

SC 2. Do the following Self-Check activity about digestion.