Flashcards in tubular function Deck (17)
Loading flashcards...
1
how much is reabsorbed in the renal corpuscle?
99%
2
describe sodium handling
na transport facilitates reabsorption of nutrients, water and ions
65% reabsorbed in PCT
25% reabsorbed in ascending loop of henle
8% in DCT- depending on rn
98% reabsorbed
3
what is passive diffusion?
movement of molecules from high to low concentration until equilibrium is reached
4
in what direction is the concentration gradient between the PCT and peritubular capillaries
high -> low
tubules lumen -> tubule wall -> interstitial space -> peritubular capillary
5
how does water move?
aquaporins
6
how do glucose and aa move across the apical surface?
sodium co-transporters
7
describe how the proximal tubule reabsorbs 2/3 of filtrate
Na+K+ pump on basolateral membrane facilitates 65% reabsorption, everything else follows Na+ eg. water follows by osmosis, chroride follows electrical gradient
8
what does Na+ active transport facilitate?
100% nutrient reabsorption
65% water reabsorption
65% neg ions follow electrical gradient
no effect on waste removal
remaining filtrate continues through loop of henle
9
what are the 3 parts of the loop of henle?
thin descending limb
thin ascending limb
thick ascending limb
10
what are the loop rules?
thin descending contains aquaporins-freely permeable to water
both ascending do not contain aquaporins-impermeable to water
thick ascending - site of active sodium reabsorption
11
how does sodium reabsorption occur?
via NKCC2 on apical membrane
12
what is countercurrent multiplication?
mechanism for reabsorbing water from tubular fluid
energy used to create osmotic gradient-produce concentrated urine
13
why does the vasa recta employ counter current exchange?
to maintain concentration gradient of the medulla
14
what is the function of the distal convoluted tubule?
fine-tuning - site of fluid volume and electrolyte regulation
Na & water reabsorption hormonally reg.
ADH- increases reabsorption
aldosterone- increases Na+ reabsorption
AND- promotes Na+ secretion
15
how does ADH affect urine production?
acts on distal and collecting tubules
insertion of aquaporins allows water to be reabsorbed from the filtrate
small vol. cons. urine prod.
16
how does aldosterone affect urine production?
acts on distal and collecting tubules
upregulates activity and insertion of Na+K+ pumps and channels
small vol. conc. unrine prod.
17
