Textbook Question
Describe the regulation of the cephalic, gastric, and intestinal phases of gastric secretion.
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Ch. 23 The Digestive System
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732
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Table of contents
- Ch. 1 The Human Body: An Orientation25
- Ch. 2 Chemistry Comes Alive24
- Ch. 3 Cells: The Living Units24
- Ch. 4 Tissue: The Living Fabric19
- Ch. 5 The Integumentary System12
- Ch. 6 Bones and Skeletal Tissues19
- Ch. 7 The Skeleton14
- Ch. 8 Joints7
- Ch. 9 Muscles and Muscle Tissue26
- Ch. 10 The Muscular System25
- Ch. 11 Fundamentals of the Nervous System and Nervous Tissue23
- Ch. 12 The Central Nervous System25
- Ch. 13 The Peripheral Nervous System and Reflex Activity30
- Ch. 14 The Autonomic Nervous System16
- Ch. 15 The Special Senses26
- Ch. 16 The Endocrine System26
- Ch. 17 Blood27
- Ch. 18 The Cardiovascular System: The Heart25
- Ch. 19 The Cardiovascular System: Blood Vessels27
- Ch. 20 The Lymphatic System and Lymphoid Organs and Tissues16
- Ch. 21 The Immune System: Innate and Adaptive Body Defenses27
- Ch. 22 The Respiratory System21
- Ch. 23 The Digestive System31
- Ch. 24 Nutrition, Metabolism, and Energy Balance26
- Ch. 25 The Urinary System26
- Ch. 26 Fluid, Electrolyte, and Acid-Base Balance24
- Ch. 27 The Reproductive System24
- Ch. 28 Pregnancy and Human Development25
- Ch. 29 Heredity11
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
Chapter 23, Problem 21
Describe the two phases of swallowing, noting the organs involved and the activities that occur.
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The first phase of swallowing is the **buccal phase** (voluntary phase). It begins in the mouth when the tongue pushes the bolus (chewed food mixed with saliva) against the hard palate and then toward the oropharynx. The tongue and hard palate are the primary structures involved in this phase.
During the buccal phase, the soft palate rises to close off the nasopharynx, preventing food from entering the nasal cavity. This ensures the bolus is directed toward the pharynx.
The second phase is the **pharyngeal-esophageal phase** (involuntary phase). This phase begins when the bolus enters the oropharynx. The pharynx and esophagus are the primary organs involved in this phase.
In the pharyngeal-esophageal phase, the epiglottis closes over the laryngeal opening to prevent food from entering the trachea. Simultaneously, the upper esophageal sphincter relaxes, allowing the bolus to enter the esophagus.
Peristalsis (a series of wave-like muscle contractions) propels the bolus down the esophagus toward the stomach. The lower esophageal sphincter relaxes to allow the bolus to enter the stomach, completing the swallowing process.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Pharyngeal Phase
The pharyngeal phase of swallowing is a reflexive process that begins when food reaches the back of the throat. During this phase, the soft palate elevates to close off the nasal passages, and the epiglottis folds down to cover the trachea, preventing food from entering the airway. The pharyngeal muscles contract to push the bolus down into the esophagus, ensuring a safe and efficient transition from the mouth to the digestive tract.
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Phases of Mitosis
Esophageal Phase
The esophageal phase follows the pharyngeal phase and involves the movement of the bolus through the esophagus to the stomach. This phase is characterized by peristalsis, a series of wave-like muscle contractions that propel the bolus downward. The lower esophageal sphincter relaxes to allow the bolus to enter the stomach, completing the swallowing process. This phase is involuntary and typically takes about 8 to 20 seconds.
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Anatomy of the Swallowing Process
Understanding the anatomy involved in swallowing is crucial for comprehending the phases of this process. Key organs include the mouth, pharynx, esophagus, and the associated muscles and sphincters. The tongue plays a vital role in forming the bolus and initiating swallowing, while the soft palate, epiglottis, and esophageal sphincters ensure that food is directed appropriately and safely through the digestive system.
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Related Practice
Textbook Question
Lara was on a diet but she could not eat less and kept claiming her stomach had a mind of its own. She was joking, but indeed, there is a 'gut brain' called the enteric nervous system. Is it part of the parasympathetic and sympathetic nervous system? Explain.
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Textbook Question
Describe the role of these cells found in gastric glands: parietal, chief, mucous neck, and enteroendocrine.
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Textbook Question
a. What is the relationship between the cystic, common hepatic, bile, and pancreatic ducts?
b. What is the point of fusion of the bile and pancreatic ducts called?
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Textbook Question
a. Describe the boundaries of the oral cavity.
b. Why do you suppose its mucosa is stratified squamous epithelium rather than the more typical simple columnar epithelium?
Textbook Question
Make a simple line drawing of the organs of the alimentary canal and label each organ. Then add three labels to your drawing—salivary glands, liver, and pancreas—and use arrows to show where each of these organs empties its secretions into the alimentary canal.
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