Elimination of waste product from a normal person requires minimal amount of urine of
**Core Concept**
The question is testing the concept of minimal urine production required for waste elimination in a normal individual. This is related to the renal concentrating ability and the glomerular filtration rate (GFR). A normal kidney can concentrate or dilute the urine to eliminate waste products efficiently.
**Why the Correct Answer is Right**
The kidneys can concentrate urine to a maximum osmolality of around 1200 mOsm/kg by reabsorbing water from the collecting ducts. This requires a minimal amount of urine to be produced, which is around 400-500 mL/day in a normal individual. The kidneys achieve this by adjusting the reabsorption of water and electrolytes in response to changes in body fluid osmolality. The hormone vasopressin (ADH) plays a crucial role in regulating water reabsorption in the collecting ducts.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the minimal urine production required for waste elimination is not related to the glomerular filtration rate (GFR) alone. While GFR is an important factor, it is not the only factor that determines the minimal urine production.
* **Option B:** This option is incorrect because the minimal urine production required for waste elimination is not related to the surface area of the kidneys. The surface area of the kidneys does not directly affect the concentrating ability of the kidneys.
* **Option C:** This option is incorrect because the minimal urine production required for waste elimination is not related to the blood pressure alone. While blood pressure affects renal perfusion, it is not the primary factor that determines the minimal urine production.
**Clinical Pearl / High-Yield Fact**
A normal kidney can concentrate urine to a maximum osmolality of around 1200 mOsm/kg, which requires a minimal amount of urine to be produced. This is achieved by adjusting the reabsorption of water and electrolytes in response to changes in body fluid osmolality, with the hormone vasopressin (ADH) playing a crucial role.
**Correct Answer:** D. 500