GIT hormones with a major effect on the stomach include the following except:

Correct Answer: B

Rationale: Secretin is the correct answer because it is not a hormone that directly affects the stomach. Gastrin stimulates gastric acid secretion, GIP enhances insulin release, and neurotensin regulates gastric motility. Secretin primarily targets the pancreas and liver, stimulating the release of bicarbonate-rich pancreatic juice. This hormone does not have a direct major effect on the stomach like the other options. Therefore, Secretin is the exception among the listed GIT hormones affecting the stomach.

Correct Answer: C

Rationale: The correct answer is C: small intestine. Primary carcinoma is least common in the small intestine compared to the other choices. This is because the small intestine has a lower incidence of cancer compared to the esophagus, stomach, and colon. Factors contributing to this lower incidence include less exposure to carcinogens, a relatively smaller surface area, and less common inflammatory conditions that can lead to cancer development. Additionally, the small intestine has a more rapid turnover of cells, reducing the likelihood of cancerous mutations accumulating. Therefore, the small intestine is the least common site for primary carcinoma among the options provided.

Correct Answer: B

Rationale: The correct answer is B because the normal concentration of bilirubin in the plasma is about 0.8 gm%, which is a commonly accepted fact in medicine. Bilirubin is a product of hemoglobin breakdown and is typically measured in the blood to assess liver function and detect certain medical conditions. A, C, and D are incorrect: A: Myenteric plexus controls GIT motility, not secretion. C: Submucosal plexus controls GIT secretion, not motility. D: Pepsinogen activation needs hydrochloric acid (HCl) in the stomach, not calcium.

Correct Answer: B

Rationale: Step 1: CCK (Cholecystokinin) is released in response to the presence of fats and proteins in the small intestine. Step 2: CCK inhibits stomach motility to allow enough time for the gallbladder to release bile. Step 3: This slowing down of stomach motility aids in the digestion and absorption of fats. Step 4: Choices A, C, and D are incorrect as CCK does not directly affect gastric secretion, pancreatic enzyme secretion, or increase pancreatic secretions rich in bicarbonate.

Correct Answer: D

Rationale: The correct answer is D, Cholecystokinin (CCK). CCK is produced in the small intestine in response to the presence of fats and proteins. It stimulates the release of digestive enzymes from the pancreas to aid in digestion. Insulin (A) and Glucagon (B) are involved in regulating blood sugar levels, not digestive enzyme release. Secretin (C) primarily stimulates the release of bicarbonate from the pancreas to neutralize stomach acid, not digestive enzymes.