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USMLE Step 1 Anatomy & Physiology — practice by topic

Browse 42 questions across 1 Anatomy & Physiology topics. Choose what you want to revise, then open a question to check its answer and worked solution.

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Anatomy & Physiology topics

The Digestive System (42)

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How long is the alimentary canal in a living person?Read the answer and worked solution →Which nerve plexus sits in the muscularis layer and sets the rhythm and force of its contractions?Read the answer and worked solution →The mouth, pharynx and esophagus have no serosa. What forms their outermost layer instead?Read the answer and worked solution →Which one of these counts as one of the six processes of digestion?Read the answer and worked solution →

Worked practice questions

How long is the alimentary canal in a living person?

  1. About 3.05 meters, or 10 feet
  2. About 7.62 meters, or 25 feet
  3. About 10.67 meters, or 35 feet
  4. About 15.2 meters, or 50 feet
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Correct answer: B. About 7.62 meters, or 25 feet

1. The alimentary canal is a one-way tube running from the mouth to the anus. 2. During life its length is about 7.62 meters, which is 25 feet. 3. The figure of 10.67 meters, or 35 feet, is the length measured after death, once smooth muscle tone is lost. 4. About 3.05 meters is the length of the small intestine alone, not the whole canal. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.1 Overview of the Digestive System_

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Which nerve plexus sits in the muscularis layer and sets the rhythm and force of its contractions?

  1. The submucosal plexus of Meissner
  2. The celiac trunk of the abdomen
  3. The myenteric plexus of Auerbach
  4. The lamina propria of the mucosa
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Correct answer: C. The myenteric plexus of Auerbach

1. Enteric neurons are grouped into two plexuses that sit in different layers of the canal wall. 2. The myenteric plexus, also called the plexus of Auerbach, lies in the muscularis and governs motility. 3. Motility means the rhythm and force of muscularis contractions, so this plexus is the answer. 4. The submucosal plexus of Meissner sits in the submucosa and regulates secretions instead. 5. The celiac trunk is an artery, and the lamina propria is connective tissue, so neither is a plexus. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.1 Overview of the Digestive System_

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The mouth, pharynx and esophagus have no serosa. What forms their outermost layer instead?

  1. A layer of visceral peritoneum
  2. A dense sheath of collagen fibers
  3. A fold of the greater omentum
  4. A sheet of oblique smooth muscle
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Correct answer: B. A dense sheath of collagen fibers

1. A serosa is present only where the alimentary canal lies inside the abdominal cavity. 2. The mouth, pharynx and esophagus sit outside that cavity, so they carry an adventitia instead. 3. The adventitia is a dense sheath of collagen fibers that holds these organs near the vertebral column. 4. Visceral peritoneum is the covering of the serosa itself, so it belongs to the abdominal organs. 5. The oblique smooth muscle layer is an addition to the stomach muscularis, not an outer coat. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.1 Overview of the Digestive System_

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