Loop of Henle, Distal Tubule, Collecting Duct Flashcards
% of filtered Na reabsorbed in the Loop of Henle?
25%
Descending loop is permeable only to:
Water (reabsorbed)
Osmolality of filtrate as it passes through descending, deep medullary, and ascending loop:
300 mOsms
1400 mOsm
100 mOsm
Which segment of loop is not permeable to water?
Ascending
Membrane apparatus carrying solutes from collecting tubule lumen into cell in the Thick Ascending Limb?
NKCC pump
What is the driving force of the NKCC pump?
Na
What is the limiting factor in the NKCC pump?
Cl
% of the filtered Na reabsorbed in the Thick Ascending Loop?
20%
Type of diuretic that acts on NKCC pump?
lasix (furosemide)
% of filtered Na reabsorbed in the Distal Tubule?
5%
Is distal tuble permeable to water?
no
Pump of action in the distal tubule?
Na/Cl symporter….secondary active transport driven by Na
Genetic mutation of NaCl pump in distal tubule?
Gitleman Syndrome
5 key features of Gitleman Syndrome:
- Normal BP
- Metabolic alkalosis
- hypocalciuria
- hypomagnesemia
- hypokalemia
Drugs that manipulate NaCl channel in distal tubule?
thiazide diuretics
First area with VARIABLE reabsorption of Na?
Collecting duct
0-5%
Two principle channel types in Principal cells of collecting tubules?
ENac’s (epithelial Na channels)
ROMK’s (renal outer medullary K channels)
Collecting duct permeability to water?
Variable
Primary mechanism of controlling salt reabsorption in principle cells?
Aldosterone
**regulated by RAAS
3 primary signals stimulating renin release?
- SNS–NE
- Decreased stretch in afferent arterioles
- Decreased Cl delivery to macula densa
Where is renin released from?
Juxtaglomerular cells in the afferent arteriole
Clinical triggers for renin release:
- hypovolemia
- low Na diet
- low body NaCl
- high SNS activity
4 primary actions of Angiotensin II:
- stimulates aldosterone
- systemic vasoconstriction
- stimulates proximal tubule reabsorption of Na
- Increases SNS activity
Why can aldosterone cross freely into cells?
lipophilic
