Where Are Islets of Langerhans Found?

Correct Answer: D

Rationale: The Islets of Langerhans are clusters of cells in the pancreas that regulate blood sugar levels. Choice D, Endocrine pancreas, is correct because the Islets of Langerhans are specifically located in the pancreas. Choices A, B, and C are incorrect because the Islets of Langerhans are not found in the anterior pituitary, cortex, or spleen. The pancreas is the primary organ associated with blood sugar regulation, making it the correct location for the Islets of Langerhans.

Correct Answer: D

Rationale: The correct answer is D: amylase. Gastric juice primarily contains hydrochloric acid, pepsinogen, and mucus, but not amylase. Amylase is an enzyme produced in the mouth and pancreas that helps break down carbohydrates, not typically found in gastric juice. HPO42- is a phosphate ion present in gastric juice. Lipase is an enzyme that aids in the digestion of fats and can be found in pancreatic juice, not gastric juice. Mucus is secreted by the stomach lining to protect it from the acidic environment of gastric juice.

Correct Answer: B

Rationale: The correct answer is B: increased gastric motility and emptying. CCK, or cholecystokinin, is a hormone released by the small intestine in response to the presence of fats. Its main actions include stimulating gallbladder contraction (A) to release bile for fat digestion, triggering the secretion of pancreatic juice (D) containing digestive enzymes, and inhibiting gastric motility and emptying. Therefore, increased gastric motility and emptying (choice B) is NOT an action of CCK. This is because CCK acts to slow down gastric emptying to allow for effective digestion of fats in the small intestine. Choices A, C, and D are all correct actions of CCK based on its role in the digestive process.

Correct Answer: C

Rationale: The correct answer is C because cholesterol is transported from extra-hepatic cells to the liver by high-density lipoproteins (HDLs) in the endogenous pathway. HDLs are responsible for picking up excess cholesterol from peripheral tissues and transporting it back to the liver for excretion. This process helps regulate cholesterol levels in the body. Explanation for other choices: A: Ketone bodies accumulate in DKA due to increased fatty acid breakdown, not a lack of acetyl-CoA substrate. B: Fatty acids are primarily transported in the bloodstream bound to albumin, not lipoprotein complexes. D: Eicosanoids are derived from arachidonic acid, not cholesterol.

Correct Answer: A

Rationale: The correct answer is A: ornithine. Ornithine is not a standard amino acid found in protein structures but is involved in the urea cycle. Arginine, valine, and aspartic acid are all standard amino acids that are commonly found in proteins. Ornithine is not incorporated into proteins during translation, making it the correct choice.