[Biology][Practical-6] Kidney Physiology Questions


  • What do you mean when we refer to the substance threshold about the GFR? A nutrient in the filtrate will be reabsorbed back into the bloodstream until it reaches its threshold level (glucose and amino acids 100% reabsorbed under normal conditions at the PCT)

  • The descending limb of the loop of Henle is permeable to water but not to salts

  • How does ADH function?

ADH is released from the posterior pituitary when the individual is dehydrated. It causes an increase of aquaporins on the surface of the collecting duct membrane, allowing more water to passively diffuse following the concentration gradient (that was created by the loop of Henle) back to the medulla and then eventually get reabsorbs into the blood.

  • The blood enters the kidney through the renal artery and exits through the renal vein

  • Vasoconstriction of the efferent arteriole causes an increase of the filtration rate

  • Urine Formation (3 steps)

1. Glomerular filtration
2. Tubular secretion - blood to tube
3. Tubular Reabsorption - tube to blood

  • Blood in the renal vein, after going through the kidney, will contain:

    • Less urea
    • Less water and solutes/ions
    • Less glucose and oxygen
  • The blood is filtered in Bowman´s capsule

  • Most of the selective reabsorption occurs in the proximal convoluted tubule

  • What is the composition of the filtrate?

H2O, nitrogen waste (urea, ammonia), ions (sodium, chlorine, bicarbonate), nutrients - glucose, amino acids

  • The salt gradient is established in the loop of Henle

  • The glomerulus is a dense capillary bed

  • Ultrafiltration is a mechanical process that occurs when the blood enters the body to the nephron through the glomerulus

  • Vasoconstriction of the afferent arteriole causes a decrease in the filtration rate

  • The ascending limb of the loop of Henle is permeable to salt but not water


is it ‘less urea’ and not more urea, as in isnt urea a waste product?

The renal vein goes out the kindey, it’s after the filtration.


ah yes thank you, i read it incorrectly XD

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