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Chapter 7. Gastrointestinal Physiology

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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?

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A Arrested at lower esophageal sphincter

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B Arrested at the pyloric sphincter

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C Duodenum

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D Ileum

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E Sigmoid colon

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F Excreted in feces

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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.

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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?

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A Myenteric plexus

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B Sacral parasympathetic nerves

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C Splanchnic sympathetic nerves

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D Submucosal plexus

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E Vagus nerve

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

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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?

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A Upper esophageal sphincter

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B Thoracic esophageal body

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C Abdominal esophageal body

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D Lower esophageal sphincter

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E Fundus of stomach

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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.

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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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