Lecture 8b: Regulation of Urinary Conc. by the Renal Pelvis (Bolsor)

Question 1

Fx of the extensions of the renal pelvis

Answer 1

Increases surface area and aids in actively contracting the medulla. The renal pelvis is more than just a funnel from the kidney to the ureter!

Question 2

Mechanism by which renal pelvic contractile behavior can alter renal function

Answer 2

1) smooth m. of renal pelvis contracts rhythmically
2) contractions create a pumping effect on renal medulla
3) allows for rapid diuresis during large water intake
4) urine leaving the papilla tip can reflux back around the papilla to increase amt. of water excreted

Question 3

Is default state of ureter to be closed or open?

Answer 3

closed

Question 4

how do pelvic contractions effect capillary flow in the papilla?

Answer 4

stop capillary flow during contraction. Capillary flow is stopped about 30% of the time due to this. Collecting ducts in the papilla also open and close along with the contractions

Question 5

low vs. high urine flow in ureter

Answer 5

low urine flow has small boluses of urine flowing down ureter; high urine flow has longer boluses of urine transmitted with ureter lumen staying open longer

Question 6

How does urine reflux around the papilla effect papillary urea and tissue osmolality?

Answer 6

lowers them; allows for rapid water excretion

Question 7

increased pressure in the renal medulla —> H2O in collecting duct cells

Answer 7

increases. H2O moves into the collecting duct cells

Question 8

decreased pressure in the renal medulla –> H2O in collecting duct cells

Answer 8

decreases. water moves out into the medullary interstitium where this water enters ascending vasa recta