Osmoregulation In Kidney Assignment Example | Topics and Well Written Essays - 750 words

Osmoregulation In Kidney - Assignment Example Water is passively transported across the cell membranes in reaction to ionic concentration changes. An increase in Na and K ions in the cells generate a concentration gradient resulting in increased water uptake through the process of osmosis. Similarly, the consequence of decreased ionic concentration results in water loss from the cells. Therefore, the rate of water gain or loss is regulated through specific hormones that are involved in the alteration of excretory ducts to water permeability and Na flow across the membranes. Urine is more concentrated than blood and has an osmolality of 1200 mmol/L while blood has 300 mmol/L. Renal osmoregulatory mechanisms are involved in the conversion of this osmolarity. Accordingly, human urine can be as hypo-osmotic as 50 most/L or as hyperosmotic as 1200 mm/L (Eastwood, 2009). The remarkable ability of the kidney to produce hyper/hypo-osmotic urine through osmotic gradient maintenance is largely dependent upon specific arrangement and coope rative efforts of the loop of Henle and collecting tubules in renal cortex and medulla. Juxtamedullary nephrons maintain a high osmolarity in kidneys and the countercurrent mechanisms of Vasa recta and loop of Henle are responsible for maintaining evident osmotic gradient between cortex and medulla. The filtrate passes from the cortex to the medulla in descending tubule of the loop of Henle where major amounts of the water are reabsorbed through osmosis, thus increasing the osmolarity of the filtrate.