The physiological actions of CCK include:

Correct Answer: D

Rationale: The correct answer is D: Contraction of pancreatic acini. Cholecystokinin (CCK) is a hormone that is released in response to the presence of food in the small intestine. It stimulates the contraction of the smooth muscle in the walls of the pancreatic acini, leading to the release of digestive enzymes into the small intestine to aid in digestion. This action is crucial for the proper breakdown of food molecules. Options A, B, and C are incorrect because CCK does not have a direct effect on oesophageal motility, the sphincter of Oddi, or bile synthesis.

Correct Answer: D

Rationale: The correct answer is D because iron absorption is regulated to meet the body's needs. When body stores are low or erythropoiesis is increased, absorption increases. This process occurs mainly in the duodenum and upper jejunum, not the terminal ileum as stated in option C. Option A is incorrect because HCl aids in converting iron into a more absorbable form but does not determine the percentage absorbed. Option B is incorrect as the majority of iron absorption occurs in the duodenum and upper jejunum, not the small intestine in general.

Correct Answer: A

Rationale: The correct answer is A: resecting the constricted segment. In Hirschsprung's disease, there is a lack of ganglion cells in the distal bowel causing a functional obstruction. The treatment involves surgically removing the affected segment to allow normal bowel function. Resecting the dilated segment (choice B) is not effective as the issue lies in the constricted area. Colectomy and ileostomy (choice C) is an extreme measure and is usually reserved for severe cases. Avoiding surgical intervention (choice D) is not recommended as it can lead to complications and worsen the condition.

Correct Answer: B

Rationale: B: Carcinoma of the esophagus is difficult to cure due to local spread. Esophageal cancer often presents at advanced stages, making complete surgical resection challenging. Local spread to nearby structures like the trachea or blood vessels hinders curative treatment. This is supported by the fact that esophageal cancer has a poor prognosis, with a 5-year survival rate of around 20%. A: This is incorrect because esophageal carcinoma is often diagnosed at advanced stages when symptoms appear, making it less curable than early-stage cancers. C: Early widespread metastases are not a defining feature of esophageal carcinoma. Metastases typically occur at later stages of the disease. D: Esophageal carcinoma can be differentiated or undifferentiated, but this does not impact the difficulty in curing the cancer due to local spread.

Correct Answer: B

Rationale: The correct answer is B: Metabolic alkalosis. Vomiting causes loss of stomach acid (HCl), leading to an increase in blood pH and bicarbonate levels, resulting in metabolic alkalosis. Choice A is incorrect because vomiting does not lead to an increase in acid levels. Choices C and D are incorrect as they are related to respiratory disorders, not directly caused by vomiting. In summary, vomiting leads to metabolic alkalosis due to loss of stomach acid.