Guided Lecture Notes
Chapter 27: Structure and Function of the Gastrointestinal System
Learning Objective 1. Describe the physiologic functions of the four parts of the
digestive system.

List other names used for the digestive tract, and identify the accessory organs of
digestion (refer to Fig. 27-1).

List the organs that comprise the four components of the digestive tract, and
describe the function of each (refer to PowerPoint Slide 2 and Fig. 27-1).
Learning Objective 2. List the five layers of the digestive tract and describe their
functions.

Identify the five layers of the GI tract, and describe the structure and function of
each (refer to PowerPoint Slide 4 and Fig. 27-3).

Describe the function of the mesentery and the greater omentum (refer to Figs.
27-4 and 27-5).
Learning Objective 3. Characterize the function of the intramural neural plexuses in
control of gastrointestinal function.

Define tonic, rhythmic, and peristaltic movement (refer to Fig. 27-2).

Identify the two networks that include intramural neurons, and explain the
structure and function of each (refer to Fig. 27-6).
Learning Objective 4. Compare the effects of parasympathetic and sympathetic activity
on the motility and secretory functions of the gastrointestinal tract.

Differentiate between sympathetic and parasympathetic innervation, and describe
the effects exerted by each system (refer to Fig. 27-7).
Learning Objective 5. Trace a bolus of food through the stages of swallowing.

Describe the functions of chewing and swallowing.

Describe the three phases of swallowing, and explain the mechanism that prevents
gastric reflux.

Differentiate between gastric, small intestine, and colonic motility.
Learning Objective 6. Describe the action of the internal and external sphincters in the
control of defecation.

Describe the anatomy and physiology of the rectum and anal canal (refer to Fig.
27-8).

Explain the function of the internal and external sphincter muscles with regard to
defecation control.
Learning Objective 7. State the sources and functions of water and electrolytes that are
secreted in digestive secretions.

Identify the components of GI tract secretions, and state the amount of each (refer
to Table 27-1).

Describe the source of these secretions, and identify factors that influence the
amount of secretions.
Learning Objective 8. Explain the protective function of saliva.

Identify the location of salivary glands, and explain the purpose of saliva.
Learning Objective 9. Describe the function of the gastric secretions in the process of
digestion.

Identify the two types of glands that produce gastric secretions, and explain their
function.

List common drugs that may damage the gastric mucosa.
Learning Objective 10. List three major gastrointestinal hormones and cite their
functions.

Describe the source and function of gastrin, ghrelin, and secretin (refer to Table
27-2).

Explain how GI hormones are controlled.
Learning Objective 11. Describe the site of gastric acid and pepsin production and
secretion in the stomach.

Identify the two types of glands in the stomach mucosa.

Describe the source and function of gastric acid and pepsin.
Learning Objective 12. Describe the function of the gastric mucosal barrier.

Describe the structure of the GI mucosa, and explain its function (refer to Fig. 279).
Learning Objective 13. Describe the functions of the secretions of the small and large
intestines.

Identify the sources and types of intestinal secretions, including those added from
accessory organs of digestion (liver and pancreas).
Learning Objective 14. Differentiate digestion from absorption.

Define digestion and absorption, and explain the difference.
Learning Objective 15. Explain the function of the intestinal brush border enzymes.

Identify distinguishing characteristics of the small intestine (refer to Fig. 27-10).

Describe the function of microvilli (refer to Fig. 27-11).

Explain the importance of brush border enzymes.
Learning Objective 16. Compare the digestion and absorption of carbohydrates, fats,
and proteins.

Using examples, identify the origin of and describe the digestion and absorption
of carbohydrates, fats, and proteins (refer to PowerPoint Slides 10-12).

Identify the enzymes used in the digestion of carbohydrates, fats, and proteins
(refer to Table 27-3).
Learning Objective 17. Describe the physiologic mechanisms involved in anorexia,
nausea, and vomiting.

Define and compare the causes, clinical manifestations, and treatments of
anorexia, nausea, and vomiting.