Loop of Henle + Regulated transport

true or false: Osmolarity of intersitial fluid of renal medulla varies with depth

true

osmolarity is lower where?

cortex

osmolarity is deeper where?

into the medulla (near renal pelvis)

What is critical to water reabsorption?

gradient

What is the countercurrent multiplier?

two tubules in proximity with flow in opposite direction as it establishes medullary osmotic gradient

What happens to water and solutes in the descending limb?

it’s permeable to water and impermeable to solutes

What happens in the thick ascending limb?

water is impermeable and uses active solute transport

fluid enters the loop at…

300 mOsm

The renal medulla concentrated to…

1200-1400 mOsm

The fluid leaves the loop at…

100 mOsm

Does Na+ reabsorb or secrete in distal tubule and collecting duct?

reabsorb

Does K+ reabsorb or secrete in distal tubule and collecting duct?

secrete

What ion does H20 follow in the distal tubule and collecting duct?

Na+

What happens during secretion?

solutes moves from pertitubular capillaries into tubules (K+ and Na+)

Is the barrier same as for reabsorption?

YES

Is the transport mechanism the same but goes in opposite directions

Yes, they have the same transport mechanism and goes in opposite directions

What are the secreted substances?

K+, H+, choline, creatine, and penicillin

What is the equation to calculate amount of substance excreted?

amount filtered + amount secreted - amount absorbed

Renal processing is determined by 2 simple rules…

if amount of solute excreted per minute is less than filtered load → solute was reabsorbed. If amount of solute excreted per minute is greater than filtered load → solute was secreted.

What is the equation for excretion rate?

U(x) * V; U(x)= concentration in urine; V= urine flow rate

What is clearence?

volume of plasma from which a substance has been removed by kidneys per unit time (volume of plasma that contains the amount of a substance that was excreted per unit time).

What is the equation for clearance

excretion rate/plasma concentration= U(x)*V/P(x)

If C(x) > GFR, then…

substance was secreted

if C(x) < GFR, then…

substances was reabsorbed

If neither secreted nor reabsorbed, then…

C(x)=GFR

What is a solute that is an example that neither secretes or reabsorbs?

inulin