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, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- 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 Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook
Chapter 24, Problem 23
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
Verified step by step guidance1
Step 1: Understand the role of the parasympathetic nervous system in the gastrointestinal (GI) tract. The parasympathetic system generally promotes 'rest and digest' activities, which include increasing motility and secretion in the intestines.
Step 2: Recall that increased parasympathetic stimulation typically enhances intestinal motility, meaning it increases the contractions that move food through the digestive tract.
Step 3: Recognize that parasympathetic stimulation also increases secretion of digestive enzymes and fluids to aid digestion, rather than decreasing it.
Step 4: Consider the effect on local reflexes and segmentation. Parasympathetic activity tends to enhance local reflexes and segmentation (mixing movements), not decrease them.
Step 5: Based on these physiological principles, conclude that increased parasympathetic stimulation would not cause any of the decreases listed in options (a) through (d), so the correct choice aligns with option (e) None of these.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Parasympathetic Nervous System and Gastrointestinal Function
The parasympathetic nervous system primarily stimulates digestive activities by increasing motility and secretion in the gastrointestinal tract. It promotes processes like peristalsis and segmentation to aid digestion and nutrient absorption.
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Function of the Parasympathetic Nervous System
Intestinal Motility and Segmentation
Intestinal motility refers to the movements of the digestive tract that mix and propel contents. Segmentation is a type of motility involving rhythmic contractions that mix intestinal contents, enhancing digestion and absorption.
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3:06Motility in the Small Intestine
Local Reflexes in the Intestine
Local reflexes in the intestine are neural circuits within the enteric nervous system that regulate motility and secretion independently of the central nervous system. Parasympathetic stimulation generally enhances the sensitivity and activity of these reflexes.
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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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How does each of the three phases of gastric secretion promote and facilitate gastric control?
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What three basic mechanisms regulate the activities of the digestive tract?
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What are the six main processes of the digestive system?
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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?