Question

what do you know about briefly the three steps of formation of urine (filtration, reabsorption and secretion)? Please explain to me every single step in detail because I don't understand. Thank you!

Answer 1

ANSWER :

The complete process of urine formation comprises three main steps; filtration, reabsorption, and secretion. The filtration step occurs within the glomerulus that located in Bowman's capsule (filtration body) of kidney nephrons. During filtration process, all the metabolic wastes (e.g.- urea), drugs, and whole blood plasma (except plasma proteins) filtered out in the Bowman's capsule.

In next step of reabsorption, most of the filtered substances from blood plasma (e.g.- glucose, electrolytes, amino acids, & water) reabsorb in the proximal convulated tubule (PCT) of the renal tubule from the lumen into the blood capillaries (peritubular capillaries & vasa recta) present in the surrounding of renal tubules. The remaining process of reabsorption occurs in loops of Henle, DCT and collecting duct of nephron via specific transportation methods (active and passive)

At the final step of secretion, the some non-essential substances such as urea, uric acid, and water also secreted from the peritubular capillaries back into the filtrate present in the lumen of proximal convulated tubule (PCT) and collecting duct, which requires to produce urine with appropriate tonicity and keep maintain the osmolarity equilibrium within the blood plasma.