Loop of Henle (Muster) - W2 Flashcards
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
