Complete the following sentence: The main target for antidiuretic hormone is the…

Correct Answer: D

Rationale: The correct answer is D: Kidney. Antidiuretic hormone (ADH) acts on the kidneys to regulate water balance by increasing water reabsorption, thus reducing urine output. This hormone helps maintain proper fluid balance in the body. The other choices (A: Pancreas, B: Liver, C: Uterus) are incorrect because they do not play a direct role in water balance regulation or response to ADH stimulation. The kidney is the main target organ for ADH due to its crucial role in water reabsorption and urine concentration.

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.

Correct Answer: C

Rationale: The correct answer is C: nervous system. The endocrine system regulates body functions through hormones, while the nervous system controls body functions through electrical impulses. Both systems coordinate and control various bodily functions. The skeletal system (A) supports and protects the body, the immune system (B) defends against pathogens, and the respiratory system (D) facilitates gas exchange. However, these systems do not primarily regulate and control bodily functions like the endocrine and nervous systems.