Kidney physiology Flashcards
The proximal tubule is responsible for resorbing most filtered organic compounds (amino acids, glucose, other crubs, water soluble vitamines, ketones, short chain fatty acids). This is achieved via ______ with ______. The concentration gradient of ____ from the lumen to the proximal tubule cell is maintained by ____ at the _____ membrane.
The proximal tubule is responsible for resorbing most filtered organic compounds (amino acids, glucose, other crubs, water soluble vitamines, ketones, short chain fatty acids). This is achieved via couple facilitated diffuse with sodium. The concentration gradient of sodium from the lumen to the proximal tubule cell is maintained by active pumping of sodium into the blood at the basolateral membrane.
___ is the principle cation in plasma typically having a concentration of about _____.
Sodium, 140mEq/L
Normally, carbonic anhydrase catalyzes a reversible enzymatic reaction _____ + _____ <—> _____. ___ acid is then spontaneously converted to _____ and _____.
Normally, carbonic anhydrase catalyzes a reversible enzymatic reaction CO2 + H2O <—> H2CO3. Carbonic acid (H2CO3) is then spontaneously converted to bicarbonate (HCO3-) and hydrogen ion (H+).
____ is the principle anion in plasma with a typical concentration of about ___
Chloride, 100mEq/L
Approximately ____% of sodium is reabsorbed in the proximal tubule. This is driven by _____ on the basolateral membrane of proximal tubule cells. At the luminal membrane, sodium follows its ______
Approximately 65% of sodium is reabsorbed in the proximal tubule. This is driven by Na/K exchangers on the basolateral membrane of proximal tubule cells. At the luminal membrane, sodium follows its concentration gradient into the cell
Fluid into the proximal convoluted tubule just before entering the loop of henle is ___-osmotic
iso-osmotic
Following sodium, about ___% of water is reabsorbed in the proximal tubule.
65%
Chloride is reabsorbed in the proximal tubule due to 1) an _____ gradient create by reabsorption of sodium as well as the 1) ____ gradient created by reabsorbtion of water
Chloride is reabsorbed in the proximal tubule due to 1) an electrical gradient create by reabsorption of sodium as well as the 1) concentration gradient created by reabsorbtion of water
What is reabsorbed in the proximal tubule?
1) 65% of sodium, chloride and water
2) 100% organic compounds (glucose, amino acids, water soluble vitamins, short chain fatty acids)
3) 50% of urea
4) 80-90% of bicarbonate
In animal on carnivorous or omnivorous diets, ____% of filtered bicarbonate is reabsorbed in the proximal tubule. Since the luminal border of the proximal tubule is ____ to bicarbonate, the net reabsorption of sodium bicarbonate is accomplished via several steps. First, coupled facilitated diffusion of ___ and ____ allows for ____ and bicarbonate in the lumen to spontaneously form _____. The enzyme _____ lives in the luminal brush border; it reversibly dehydrates ____ into ____ and ____. ____ diffuses freely into the luminal cell where ____ rehydrates into ____ which spontaneously converts to ____ and ____. The basolateral membrane is permeable to _____, so it then diffuses into the ____ and then the _____.
In animal on carnivorous or omnivorous diets, 80-90% of filtered bicarbonate is reabsorbed in the proximal tubule. Since the luminal border of the proximal tubule is impermeable to bicarbonate, the net reabsorption of sodium bicarbonate is accomplished via several steps. First, coupled facilitated diffusion of Na (into cell) and H+ (into lumen) allows for H+ and bicarbonate in the lumen to spontaneously form carbonic acid. The enzyme carbonic anhydrase lives in the luminal brush border; it reversibly dehydrates carbonic acid into water and CO2. CO2 diffuses freely into the luminal cell where carbonic anhydrase rehydrates it into carbonic acid. Carbonic acid spontaneously converts to bicarb and H+. The basolateral membrane is permeable to bicarbonate so it then diffuses into the interstitial fluid and then the plasma.
Carbonic anhydrase inhibitors create metabolic _____ as well as diuresis due to the large amount of _____ and ____ left in the tubular lumen.
Carbonic anhydrase inhibitors create metabolic acidosis as well as diuresis due to the large amount of sodium bicarbonate and water left in the tubular lumen.
The luminal membrane of the proximal tubule is relatively freely permeable to ___ (5 things). It is moderately permeable to ____. However it is relatively impermeable to ____.
freely permeable to: sodium, water, chloride, carbon dioxide and small organic molecules. moderately permeable to urea. impermeable to bicarbonate.
