ANATOMY

Detailed explanation-1: -The kidney is divided into two parts: the outer cortex and the inner medulla. In the cortex, the osmolarity is relatively low (think less salty), around 300 mOsm/L or so, but as you travel further down into the medulla, the osmolarity gets much higher (think more salty).

Detailed explanation-2: -The filtrate and surrounding interstitial fluid are at their highest osmolarities at the bottom of the loop of Henle. As the filtrate continues on, it enters the thin ascending limb of the loop of Henle, which is impermeable to water.

Detailed explanation-3: -Concentration of the filtrate primarily occurs in the collecting duct, and the distal convoluted tubule transports urine from the loop of Henle to the collecting duct. Filtration occurs in the glomerulus and Bowman’s capsule, know together as the renal corpuscle.

Detailed explanation-4: -The distal convoluted tubule (DCT) is a short nephron segment, interposed between the macula densa and collecting duct. Even though it is short, it plays a key role in regulating extracellular fluid volume and electrolyte homeostasis.