Question

Write a concise but complete explanation of how the anatomical structure of the kidney enables it to produce concentrated urine.

Write a concise but complete explanation of how the anatomical structure of the kidney enables it to produce concentrated urine.

Hint: It's important to talk about the gross anatomical layout of the kidney (organization of the cortex and medulla) to answer this. It it also crucial to talk about the histological structure of nephrons, and the role of ADH.

Remember the 100 word limit.

Answer 1

Answer:urine formation occurs by glomerular filtration,tubular absorption and tubular secretion.

Maximum sodium and water reabsorption takes place in proximal convuluted tubule.In pct carbonic anhydrase enzyme is responsible for breakdown of H2CO3 into CO2 and H2O and also combining them to form H2CO3.H2CO3 in epithelial cells breakdown into H+ and HCO3-,bicarbonate is reabsorbed back into systemic circualation whereas with the Na+-H+ exchanger for every H+ ion movement into lumen of pct there is absorbtion of Na+ ions along with water.

In descending limb of loop of henle,both H2O and solutes absorbtion occurs.

thick ascending limb is impermeable to water.25% of Na+ and cl- is reabsorbed back into systemic circulation,with the help of Na+/k+/2cl- transporter Na+ and cl- are reabsorbed and postive ions loss creates a negative gradient in cells of thick ascending limb leads to absorbtion of Ca2+ and Mg2+.

In collecting ducts,the remaining Na+ is reabsorbed and causes depolarisation of epithelial cells which activates H+ ATPase and ROMK channels leads to loss of H+ and K+ ions in urine respectively.uric acid is also excreted in collecting ducts.

All these steps finally leads to the formation of concentrated urine.