Which of the following correctly describes the role of the stomach's fundus in digestion?
It digests triglycerides with bile
It stores food and gases prior to chyme formation
It produces intrinsic factor for protein absorption
It initiates absorption of nutrients
It absorbs vitamin B12 directly
The Correct Answer is B
A. It digests triglycerides with bile: Bile is synthesized by hepatocytes and secreted into the duodenum, not the stomach. Triglyceride emulsification occurs distal to the pyloric sphincter. The gastric environment is too acidic for biliary salts to function effectively.
B. It stores food and gases prior to chyme formation: The fundus is the superior, dome-shaped portion of the stomach that accommodates ingested boluses through receptive relaxation. It serves as a physiological reservoir for undigested food and accumulated digestive gases. It allows for gradual processing into chyme.
C. It produces intrinsic factor for protein absorption: While parietal cells in the fundus and body secrete intrinsic factor, this glycoprotein is specifically required for vitamin B12 absorption in the ileum. It is not involved in the proteolytic cleavage of proteins. Protein digestion requires pepsin.
D. It initiates absorption of nutrients: The gastric mucosa lacks the specialized villi and microvilli necessary for significant nutrient uptake. Absorption is almost exclusively a function of the small intestinal enterocytes. The fundus is primarily a site for storage and mechanical processing.
E. It absorbs vitamin B12 directly: Vitamin B12 cannot be absorbed in the stomach; it must first bind to intrinsic factor. The resulting complex travels to the terminal ileum for receptor-mediated endocytosis. Direct gastric absorption of this vitamin does not occur.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
False:The liver is divided into two primary lobes by the falciform ligament (labeled C). The right lobeis the significantly larger portion (labeled A). The left lobeis the smaller portion located on the opposite side of the ligament, which is where letter D is pointing.
Correct Answer is B
Explanation
A. Propulsion:This movement pushes the gastric contents toward the pyloric sphincter through peristaltic waves. While it is a necessary part of the gastric cycle, its primary direction is forward. It does not describe the mixing reflux.
B. Retropulsion:When a peristaltic wave reaches the closed pyloric sphincter, most of the chyme is forced backward into the stomach body. This high-velocity reverse flow facilitates intense mechanical mixing and further reduction of particle size. It is critical for chyme homogenization.
C. Segmentation:This is the primary mixing movement of the small intestine, characterized by localized rhythmic contractions of the circular muscle. It does not occur in the stomach and does not involve the same retrograde propulsion. It is an oscillating motion.
D. Peristalsis:In the stomach, peristalsis refers to the rhythmic waves of contraction moving from the fundus toward the antrum. While it drives the process of mixing, it is a general term for propulsive movement. Retropulsion is the specific mixing consequence.
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