Gastrointestinal physiology
Practice questions with explanations

C. Autonomic neuropathy impairs vagal control of gastric motility, producing erratic emptying and unpredictable glucose absorption

Erratic emptying makes matching insulin to carbohydrate absorption very difficult, producing unexplained hypoglycaemia after meals followed by later hyperglycaemia. Adjusting insulin timing, smaller frequent low-fat meals, and prokinetics form the approach, and drugs that further slow emptying are avoided.

B. In the terminal ileum, bound to intrinsic factor produced by gastric parietal cells

The dependence on both a gastric product and a distal small bowel site explains the causes of deficiency: pernicious anaemia destroying parietal cells, gastrectomy, Crohn disease or ileal resection, and drugs such as metformin and long-term proton pump inhibitors. It also explains why deficiency takes years to appear, given substantial hepatic stores.

A. Synthetic function, since the liver makes the clotting factors and they have short half-lives

Transaminases indicate hepatocyte injury, bilirubin and alkaline phosphatase indicate cholestasis, but INR and albumin measure what the liver is actually making. Because factor VII has a half-life of hours, INR rises early in acute liver failure and is a key prognostic marker, while albumin, with a half-life of weeks, reflects chronic disease.