Textbook Question
A drop in pH below 4.5 in the duodenum stimulates the secretion of
(a) Secretin
(b) Cholecystokinin
(c) Gastrin
(d) All of these
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Ch. 24 The Digestive System
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology25
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization29
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure33
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses15
- Ch. 18 The Endocrine System21
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation26
- Ch. 22 The Lymphatic System and Immunity25
- Ch. 23 The Respiratory System4
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes30
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance17
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
Chapter 24, Problem 27
How does each of the three phases of gastric secretion promote and facilitate gastric control?
Verified step by step guidance1
Identify the three phases of gastric secretion: the cephalic phase, the gastric phase, and the intestinal phase. Each phase corresponds to different stimuli and mechanisms that regulate gastric secretions.
Explain the cephalic phase: This phase is initiated by the sight, smell, taste, or thought of food. It stimulates the brain to send signals via the vagus nerve to the stomach, promoting secretion of gastric juice, including hydrochloric acid (HCl) and pepsinogen, preparing the stomach for incoming food.
Describe the gastric phase: This phase begins when food enters the stomach, causing distension and the presence of peptides and amino acids. These stimuli activate stretch receptors and chemoreceptors, which further promote secretion of gastric juice and increase motility, enhancing digestion and mixing of food.
Outline the intestinal phase: This phase starts when chyme enters the small intestine. It involves hormonal feedback mechanisms, such as the release of secretin and cholecystokinin (CCK), which regulate and often inhibit gastric secretion to control the rate of gastric emptying and protect the intestine from excessive acidity.
Summarize how these phases work together to promote and facilitate gastric control by coordinating secretion and motility in response to neural and hormonal signals, ensuring efficient digestion and protection of the gastrointestinal tract.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cephalic Phase of Gastric Secretion
The cephalic phase is triggered by the sight, smell, taste, or thought of food, activating the brain to stimulate gastric secretions via the vagus nerve. This phase prepares the stomach for incoming food by promoting the release of gastric juices, including acid and enzymes, enhancing digestion readiness.
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Gastric Phase of Gastric Secretion
The gastric phase begins when food enters the stomach, causing distension and chemical stimulation of gastric cells. This phase promotes secretion of hydrochloric acid and pepsinogen, which aid in protein digestion, and also stimulates gastrin release, further enhancing gastric secretions and motility.
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Intestinal Phase of Gastric Secretion
The intestinal phase regulates gastric secretion as chyme enters the small intestine. It involves inhibitory signals that slow gastric acid and enzyme release to prevent overloading the intestine, ensuring controlled digestion and nutrient absorption while coordinating stomach emptying with intestinal capacity.
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Related Practice
Textbook Question
Increased parasympathetic stimulation of the intestine would result in
(a) Decreased motility
(b) Decreased secretion
(c) Decreased sensitivity of local reflexes
(d) Decreased segmentation
(e) None of these
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Textbook Question
Recently, more people have turned to surgery to help them lose weight. One form of weight control surgery involves stapling a portion of the stomach shut, creating a smaller volume. How would such a surgery result in weight loss?
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Textbook Question
Some people with gallstones develop pancreatitis. How could this occur?
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Textbook Question
What three basic mechanisms regulate the activities of the digestive tract?
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Textbook Question
Nutritionists have found that after a heavy meal, the pH of blood increases slightly, especially in the veins that carry blood away from the stomach. What causes this increase in blood pH?