Loop of Henle (Muster) - W2 Flashcards
(24 cards)
thin descending limb
permeable to water, not solutes
thin ascending limb
begins solute reabsorption, not permeable to water
How much sodium is reabsorbed in the thick ascending limb?
25%
What are the transporters on the luminal side of the thick ascending limb?
- NKCC2 - brings in Na, 2Cl, K+
- ROMK - K+ recycling into lumen
what are the transporters on the basolateral side of the thick ascending limb?
- K+ and Cl- symporter
- Cl- and K+ recycling
- 2K/3Na pump
How are calcium and magnesum reabsorbed in the thick ascending limb?
How much of each is reabsorbed?
- move paracellularly - driven by higher + charge in lumen.
- 20% calcium
- 50-60% magnesium
What 2 things can upregulate NKCC2?
- Angiotensin II
- Vasopressin
What are the genetic mutations in the thick ascending limb- what syndrome can this cause?
- Bartter syndrome
- depends on which genetic mutation for if it presents early or later in life
- causes growth and mental issues
- volume depletion
- low blood pressure
- hypokalemia
- metabolic acidosis
- hypercalciuria
What is a drug that blocks the NK2Cl channel?
lasix
What are the channels on the luminal side of the distal convoluted tubule?
- Na+/Cl- symporter = NCC channel
- TRPV5 - brings in calcium
What are the channels on the basolateral side of the distal convoluted tubule?
- Cl-
- K+/Cl- symporter
- K+ recycling
- Na+ in/Ca2+ out antiporter
- ATPase
How much of each is absorbed in the distal convoluted tubule?
sodium
calcium
magnesium
Sodium = 5%
Calcium = 7-10%
Magnesium = 10%
What is the disease that results if the NaCL transporter in the distal convoluted tubule doesn’t work?
Symptoms?
-
Gitleman Syndrome
- normal bp
- metabolic acidosis
- HYPOcalciuria
- HYPOmagnesemia
- HYPOkalemia
What drug can manipulate the Na-Cl channel?
hydrochlorothiazide
Describe the principle cell of the collecting duct?
- Principle cell
- salt, chloride reabsorption
- potassium exceretion
Describe the intercalated cell of collecting duct
- Intercalated cell
- H+ and HCO3- excretion
- K+ reabsorption
How much Na is reabsorbed in the collecting duct?
- 0 to 5%
What are the luminal transporters on the principle cell of the collecting duct?
- ENAC - reabsorbs Na+
- ROMK - lets K+ into lumen
What are the basolateral transporters on the principle cell of the collecting duct.
- K+ recycling channel
- ATPase
- aldosterone can bind to SRE
What are the effects of aldosterone binding?
- Sodium reabsorption
- K+ excretion
What does the sympathetic nervous system control?
What is it triggered by?
- Stimulates sodium uptake in proximal tubule
- increases Na-K ATPase
- Increases Na-H antiporter
- Controls afferent/efferent tone
- REDUCES renal blood flow and GFR
- Hypovolemia, Angiotensin II
What are the 3 primary signaling pathways that stimulate renin release?
- sympathetic input - NE triggers renin
- decreased stretch in afferent arterole
- decreased chloride delivery to macula densa
What 5 things does angiotensin II do?
- systemic vasoconstrictor
- proximal tubule reabsorption of sodium and stimulates ENAC
- stimulates salt appetite, thirst in CNS
- stimualtes aldosterone
- increases sympathetic activity
How does the amount of salt affect:
Creatinine clearance & sodium excretion
Plasma renin activity
Plasma Aldosterone
- clearance = lower salt = lower clearance
- more salt = higher clearance
-
renin
- lower salt = more renin
-
Plasma aldosterone
- low salt = more aldosterone
