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Chapter 7. Gastrointestinal Physiology

A healthy 28-year-old woman participated in a study of gastrointestinal function. She ingested a single nutritionally balanced meal containing small inert plastic beads, which could be visualized using medical imaging techniques. What is the most likely location of the beads 8 hours after ingestion of the meal?

A Arrested at lower esophageal sphincter

B Arrested at the pyloric sphincter

C Duodenum

D Ileum

E Sigmoid colon

F Excreted in feces

D. The microspheres travel with the meal and reflect the transit time of the meal. After 8 hours, the meal would typically progress to the distal small intestine. The beads are small enough not to be arrested by sphincters.

A 9-year-old boy awoke in the night complaining of abdominal pain that was dull and poorly localized. Which of the following pathways conveys these sensations of pain to consciousness?

A Myenteric plexus

B Sacral parasympathetic nerves

C Splanchnic sympathetic nerves

D Submucosal plexus

E Vagus nerve

C. Most afferent nerves conveying pain in the gastrointestinal tract travel in the sympathetic division of the autonomic nervous system.

A 49-year-old university professor volunteered to be the subject in a clinical demonstration in which a pressure sensor was passed an unknown distance into his esophagus via the nasopharynx. At one moment, the sensor was located in a region of tonically high resting pressure. When he was asked to swallow, there was an immediate decrease in pressure, followed by a rapid increase in the pressure at this location. Where was the pressure sensor located?

A Upper esophageal sphincter

B Thoracic esophageal body

C Abdominal esophageal body

D Lower esophageal sphincter

E Fundus of stomach

A. High resting pressure indicates the sensor was located in a sphincter. The pattern of pressure changes upon swallowing describes the action of upper esophageal sphincter.

A 61-year-old man saw his physician with a complaint of progressive difficulty swallowing solid food. He reported a weight loss of about 18 kg (40 lb) despite trying to eat. He was frequently aspirating his food. The results ...

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