I'm partially confused about the concentration gradient that nephrons create in order to facilitate reabsorption. Below is a summary that I created regarding this process. I would appreciate if someone would read it over to make sure I'm comprehending this correctly.
"The tubules of nephrons are selectively permeable to water and salts (Na+,Cl-), which creates a gradient for water and ions to move across.
The descending loop of Henle is permeable to water, but not salts. Because the interstitial fluid surrounding the Henle is hyperosmolar to the filtrate (has a higher osmolarity than), when filtrate flows down this loop, water leaves the nephron passively through osmosis, increasing the osmolarity of the filtrate.
In comparision to the descending loop, the ascending loop of Henle is permeable to salts, but not water. When filtrate flows up this loop, ions are actively transported out of the nephron, descreasing the osmolarity of the filtrate.
By the time the filtrate gets to the collecting duct, both water and salts have been removed from the filtrate. However, because the interstital fluid is AGAIN hyperosmolar to the filtrate, water leaves the nephron, AGAIN increasing the osmolarity of the filtrate, resulting in highly concentrated urine."
Let me know what you think. Thanks.
"The tubules of nephrons are selectively permeable to water and salts (Na+,Cl-), which creates a gradient for water and ions to move across.
The descending loop of Henle is permeable to water, but not salts. Because the interstitial fluid surrounding the Henle is hyperosmolar to the filtrate (has a higher osmolarity than), when filtrate flows down this loop, water leaves the nephron passively through osmosis, increasing the osmolarity of the filtrate.
In comparision to the descending loop, the ascending loop of Henle is permeable to salts, but not water. When filtrate flows up this loop, ions are actively transported out of the nephron, descreasing the osmolarity of the filtrate.
By the time the filtrate gets to the collecting duct, both water and salts have been removed from the filtrate. However, because the interstital fluid is AGAIN hyperosmolar to the filtrate, water leaves the nephron, AGAIN increasing the osmolarity of the filtrate, resulting in highly concentrated urine."
Let me know what you think. Thanks.
