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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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 24
A drop in pH below 4.5 in the duodenum stimulates the secretion of
(a) Secretin
(b) Cholecystokinin
(c) Gastrin
(d) All of these
Verified step by step guidance1
Understand the physiological context: The duodenum is the first part of the small intestine where acidic chyme from the stomach enters, and its pH can influence hormone secretion.
Recall that secretin is a hormone released by the S cells of the duodenum in response to acidic pH (typically below 4.5) to help neutralize the acid by stimulating bicarbonate secretion from the pancreas.
Recognize that cholecystokinin (CCK) is primarily released in response to fats and proteins in the duodenum, not directly by low pH.
Know that gastrin is secreted by the stomach in response to food and stimulates acid secretion, but it is not primarily triggered by low pH in the duodenum.
Conclude that a drop in pH below 4.5 in the duodenum specifically stimulates the secretion of secretin to protect the intestinal lining and regulate pH.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
pH and its Role in the Digestive System
pH measures the acidity or alkalinity of a solution. In the digestive system, different sections have specific pH ranges that regulate enzyme activity and hormone secretion. A drop in pH below 4.5 in the duodenum indicates increased acidity, triggering hormonal responses to protect the intestine and aid digestion.
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Guided course
6:28
Organs of the Digestive System
Secretin and its Function
Secretin is a hormone released by the S cells of the duodenum in response to acidic chyme entering from the stomach. It stimulates the pancreas to secrete bicarbonate-rich fluid, which neutralizes the acid, protecting the intestinal lining and creating an optimal pH for digestive enzymes.
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06:04Functional Groups
Cholecystokinin and Gastrin
Cholecystokinin (CCK) is released in response to fats and proteins, stimulating bile and pancreatic enzyme secretion. Gastrin primarily stimulates gastric acid secretion in the stomach. Unlike secretin, neither CCK nor gastrin is directly triggered by low pH in the duodenum.
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7:18Stomach Glands
Related Practice
Textbook Question
Name and describe the layers of the digestive tract, proceeding from the innermost layer nearest the lumen to the outermost layer.
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Textbook Question
How does each of the three phases of gastric secretion promote and facilitate gastric control?
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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?