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Ch. 22 The Digestive System
Amerman- Human Anatomy & Physiology 3e
Amerman3rd EditionHuman Anatomy & PhysiologyISBN: 9780138247201, 9780138247928, 9780138201814Not the one you use?Change textbook
All textbooksAmerman 3rd EditionCh. 22 The Digestive SystemProblem 18
Chapter 22, Problem 18

Which of the following occurs/occur during the cephalic phase of gastric acid secretion?
a. Stimulation of gastrin and histamine release
b. Direct stimulation of parietal cells
c. Inhibition of somatostatin release
d. Both a and b are correct
e. All of the above are correct

Verified step by step guidance
1
Understand the cephalic phase of gastric acid secretion: This phase is triggered by the sight, smell, taste, or thought of food. It is a neural response mediated by the vagus nerve, which stimulates the stomach to prepare for digestion.
Identify the key players in gastric acid secretion: Gastrin, histamine, and parietal cells are involved in stimulating acid production, while somatostatin inhibits acid secretion.
Analyze option (a): Stimulation of gastrin and histamine release occurs during the cephalic phase as the vagus nerve activates G cells (to release gastrin) and enterochromaffin-like cells (to release histamine).
Analyze option (b): Direct stimulation of parietal cells also occurs during the cephalic phase via acetylcholine released by the vagus nerve, which binds to receptors on parietal cells to promote acid secretion.
Analyze option (c): Inhibition of somatostatin release occurs because somatostatin normally suppresses acid secretion, and during the cephalic phase, the vagus nerve inhibits D cells (which produce somatostatin) to allow acid production to proceed. Based on this, evaluate whether all options (a, b, and c) are correct.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cephalic Phase of Digestion

The cephalic phase of digestion is the initial stage of gastric secretion triggered by the sight, smell, or thought of food. This phase prepares the stomach for food intake by stimulating the release of gastric juices, including hydrochloric acid and digestive enzymes, even before food enters the stomach.
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Gastrin and Histamine Release

Gastrin is a hormone produced by G cells in the stomach lining that stimulates gastric acid secretion. Histamine, released by enterochromaffin-like cells, enhances the action of gastrin by binding to H2 receptors on parietal cells, leading to increased acid production. Both are crucial for effective digestion during the cephalic phase.
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Parietal Cells and Acid Secretion

Parietal cells are specialized cells located in the gastric mucosa responsible for producing hydrochloric acid (HCl). During the cephalic phase, these cells are directly stimulated by neurotransmitters and hormones, leading to increased acid secretion, which is essential for the digestion of food and maintaining an acidic environment in the stomach.
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Related Practice
Textbook Question

Which of the following best describes the role of bile salts in lipid digestion?

a. Bile salts begin chemical digestion of lipids.

b. Bile salts bind to lipids and physically break them apart into monoglycerides and free fatty acids.

c. Bile salts bind to lipids and physically break them apart into smaller pieces.

d. Bile salts interact with pancreatic lipase and catalyze lipid breakdown.

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Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The exocrine cells of the pancreas and salivary glands are islet cells.

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Textbook Question

Lipids associate with bile salts in the small intestine to form_____ . In the enterocyte, lipids are packaged with other lipids into______.

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Textbook Question

The common hepatic duct and main pancreatic duct enter into the:

a. Pyloric sphincter

b. Duodenum

c. Ileum

d. Cecum

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Textbook Question

The peritoneal cavity is located:

a. Around each of the digestive organs

b. Between layers of mesentery

c. Superior to the greater omentum

d. Between the parietal and visceral peritoneum

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