Which of the following is NOT an excretory organ?

Correct Answer: B

Rationale: Large intestine isn't excretory removes feces, not metabolic waste (e.g., defecation vs. excretion). Kidney excretes urine true. Liver processes urea excretory. Lungs expel COâ‚‚ excretory. Intestine's fecal role distinguishes it, key to excretion definition, unlike waste-excreting organs.

Correct Answer: C

Rationale: Countercurrent exchange concentrates urine Loop of Henle/vasa recta gradient (e.g., ~1200 mOsm medulla). Bicarbonate buffers pH not concentration. Renin-angiotensin regulates BP not urine osmolality. Densification isn't a term false. Countercurrent's gradient distinguishes it, key to urine concentration, unlike buffering or BP systems.

Correct Answer: C

Rationale: Collecting ducts set urine osmolality ADH aquaporins adjust (e.g., 50-1200 mOsm). Water secretion is false reabsorbed. Most reabsorption is PCT (~65%) not collecting. ADH increases permeability opposite. Osmolality control distinguishes it, critical for concentration, unlike secretion or misattributed roles.

Correct Answer: A

Rationale: ADH is synthesized in the hypothalamus e.g., supraoptic nuclei, released by pituitary for water retention. JG cells secrete renin not ADH. Tube is ureter unrelated. Micturition is urination not hormone. Hypothalamic synthesis distinguishes it, critical for osmoregulation, unlike renal or action terms.

Correct Answer: A

Rationale: Micturition is the act of passing urine e.g., bladder emptying reflex. Vasa recta is capillaries not action. Zona glomerulosa secretes aldosterone not voiding. Macula densa is JGA not urination. Voiding process distinguishes it, critical for excretion, unlike structures or secretions.