Question

Which of the following statements on human kidney is false?
A) Renal plasma flow is normally 660ml/minute
B) Blood flow in the cortex is greater than that in the medulla
C) Reabsorption of ions and water occurs mainly in the distal convoluted tubules.
D) The renal blood flow is decreased in dehydration.

Answer 1

Hint: The nephron is the core and basic component of the kidney. Each human adult kidney includes around 1 million nephrons, while a mouse kidney encloses only about 12,500 nephrons. The kidney contributes to the control of the number of various body fluids, liquid osmolality, acid-base balance, diverse electrolyte concentrations, and elimination of toxins.

Complete answer:
The 90% of the blood that enters the kidney streams to the renal cortex and the residual amount then flows to the remaining part of the kidney involving the medulla. Renal blood flow (RBF) or renal plasma flow is the quantity of blood delivered to the kidneys per unit time. Usually, the kidneys accept 1,000 to 1,250 ml/min of blood in the average adult, i.e. about 60-75 L/hr.

In distal convoluted tubules, ions and water are reabsorbed under the control of hormone along with which urea, uric acid, creatine secreted into the tubule. During dehydration, renal blood flow is decreased so as to preserve the water and salt balance in the body and to minimize excess water loss.

Blood flow in the cortex is superior to that in the medulla. The distal convoluted tubule is the nephron section that lies right away downstream of the macula densa. In the physiology of the kidney, renal blood flow is the amount of blood delivered to the kidneys per unit time and is decreased in dehydration.

Hence, the correct answer is option (A).

Note: The kidney contributes to whole-body homeostasis, regulating acid-base balance, electrolyte concentrations, extracellular fluid quantity, and blood pressure. The kidney achieves these homeostatic functions both separately and in concert with other organs, chiefly those of the endocrine system. Diverse endocrine hormones coordinate these endocrine functions; these involve renin, angiotensin II, aldosterone, antidiuretic hormone, and atrial natriuretic peptide, among others.