Question

Describe the importance of the renal medulla as it pertains to reabsorption. Support your description by detailing at least three examples/processes/mechanisms of reabsorption

Answer 1

Kidney is responsible for excretion , 180 L of blood is filtered by the glomerulus per day but only 1.5 litres of urine is passed per day by a normal human . 99 percent is reabsorbed by the tubules in the kidney . Kidney is divided into an outer cortex and inner medulla . Medulla is the region involved in concentration of urine . It has renal pyramids between 2 renal pyramid os renal column .

The nephrons in renal pyramid is called juxtamedullary nephron and has long loop of henle and has vasa recta in it . Which is responsible for concentration of urine . Since loop of henle and vasa recta function as countercurrent mechanism.  

3 process of reabsorption in renal tubules :

• Active transport , it requires atp as energy , movement of solutes is against concentration gradient. Example glucose and aminoacids
• 67% of water will be reabsorbed by pct through osmosis along with the solutes . In the descending limb 15 % will be reabsorbed. This is an example for passive transport .
• Another transport that is cotransport like symports and antiports exists which helps in glucose and sodium ions transport .