Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

23. The Digestive System

The Stomach

Anatomy & Physiology

23. The Digestive System

The Stomach

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Problem 21

Textbook Question

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

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.

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.

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

The lamina propria forms part of the:

a. Muscularis externa

b. Submucosa

c. Serosa

d. Mucosa

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Multiple Choice

Which of the following statements about chemical digestion in the stomach are correct:

I. Lipid digestion is begun by enzymes known as lipases.

II. HCl is breaks starches into component monosaccharides.

III. Proteins are denatured by the protein pepsin.

Match the following terms with the correct definition.

__Chief cells

__Parietal cells

__Gastrin

__Pyloric sphincter

__Diffuse neuroendocrine (DNES) cells

__Gastroesophageal sphincter

__Pepsin

__Chyme

a. Hormone that stimulates multiple digestive processes

b. Enzyme that begins protein digestion

c. Produce acid and intrinsic factor

d. Liquid produced as a result of stomach churning

e. Produce pepsinogen

f. Cells in gastric glands that produce hormones

g. Controls passage of bolus from esophagus to stomach

h. Controls passage of stomach contents to duodenum

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Multiple Choice

During the intestinal phase of gastric regulation, __________.

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Multiple Choice

Within the gastric glands, which cells would you expect to find closest to the gastric pits?

Mixing of the chyme with gastric juice is achieved via:

The increased concentration of HCO₃^– in blood draining from the stomach is called __________.

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Multiple Choice

Rugae are formed by the two inner most layer of the stomach adjacent to the lumen when the stomach is empty. Knowing this, which stomach layers form the rugae?