Which of the following statements about the functioning of the kidney is CORRECT ?
I. On a average , 1100-1200 ml of blood is filtered by the kidneys per minute which constitute roughly 1/5th of the blood pumped out by both the Ventricles of the heart in a minute .
II. JGA is a special sensitive region formed by cellular modifications in the distal convoluted tubule and glomerulus at the location of their contact .
III. The ascending limb of Henle's loop is impermeable to water but allows transport of electrolytes.
IV. The collecting duct allows passage of small amounts of urea into the medullary interstitium to keep up the osmolality.