Renal Physiology II Flashcards
Chad Touchberry, PhD UMKC – SOM, Basic Medical Sciences
Why is reabsorption & secretion important?
What is mainly filtered in the proximal tubule?
What is reabsorbed in the proximal tubule into the tubular fluid?
What is mainly reabsorbed in the descending limb?
Water
What is mainly reabsorbed in the ascending limb?
What ions are reabsorbed in the distal tubule?
What ions are reabsorbed in the distal tubule?
What is reabsorbed first in the collecting duct?
Lastly, what is secreted in the collecting duct?
What is Glomerulotubular balance?
What does Glomerulotubular balance accomplish?
How does high GFR stimulate more reabsorption?
Early Proximal Tubule (67%): Na+ Co-Transport
What are the main transporters?
What percentage of Na+/Cl-/K+ and H2O are reabsorbed in the proximal tubule?
67%
What percentage of Na+ coupled HCO3- /H+ transport occurs in the proximal tubule?
80%
What percentage of Na+ coupled Glu, AA, Pi transport occurs in the proximal tubule?
98%
Where can drugs/toxins (pancuronium/morphine) build up in patients with AKI or CKD?
Proximal tubule
Toxins and drugs are secreted here. (Morpine & Pancuronium “build up” in pts w/ AKI or CKD!
What transporter is most important for Na+ & water reabs.?
What is the main function of the Na+/H+ antiporter (NHE) / Na+/HC03- co-transporter?
Where do carbonic anhydrase inhibitors work?
Carbonic anhydrase inhibitors -Na+ and bicarb bind in lumen and some is excreted. Lose K+! (moderately powerful).
What is the function of angiotensin II and where does it work?
Stimulates NHE, Na+/HCO3-, & Na+/K+ pump in the proximal tubule to ultimately raise BP
What stimulates and inhibits the Na+/Pi (NaPi) & Na+/Glucose transporters (SGLT)?
How does the Tubular fluid/Plasma concentration vary between ions and substances in the proximal tubule if:
=1
>1
<1
What limits how fast things can be reabsorbed?
Board Review…
What is the big picture of the descending LOH…
What is the big picture of the Thick Ascending Limb LOH (25%): Na/Cl/K Co-Transport?
What is the purpose of the Na+/K+/Cl- (NKCC2) transporter in the ascending LOH?
What is the role of ADH in the ascending LOH?
ADH – Increases NKCC2 activity.
What are the function of Loop diuretics in the ascending LOH?
Loop diuretics - Furosemide (Lasix)
Lose Ca2+ and Lose K+! (very powerful)
What is the purpose of the Na+/H+ antiporter (NHE) in the ascending LOH? What effect does carbonic anhydrase inhibitors have here?
What is the big picture of the Distal Tubule (5%): NaCl Co-Transport?
What is the purpose of the Na+/Cl- Cotransporter (NCC) in the distal tubule? What diuretics act here?
How are Ca2+ TRP channels regulated in the distal tubule?
Whats the big picture of the Distal cortical tubule/Cortical collecting duct?
What is the function of the principle cells in the distal corticle tubule/cortical collecting duct?
How does ADH work in the Distal cortical tubule/Cortical collecting duct?
How does amiloride work in the Distal cortical tubule/Cortical collecting duct?
What is the function of Type A intercalated cells in the Distal cortical tubule/Cortical collecting duct?
So how do the [substances] change as they move through the regions of the nephron?
So how do the [substances] change as they move through the regions of the nephron?
So how do the [substances] change as they move through the regions of the nephron?
So how do the [substances] change as they move through the regions of the nephron?
General review of transport in the nephron. (If you know this you know renal physiology)
What is the role of ADH in the body?
How can we obtain such a wide range of urine Vol and Osm?
The Loop of Henle: Counter current flow acts as a countercurrent multiplier!
Explain the countercurrent multiplier.
ADH is regulated by Osm & Vol/Pressure
ADH responds greater to changes in _________.
RAAS responds greater to changes in __________.
ADH responds greater to changes in mOsmolarity (Na+).
RAAS responds greater to changes in plasma volume.
How does ADH controls ECF via urine concentration in the distal nephron?
How does ADH respond to changes in plasma osmolarity?
ADH concentrates the urine and maximizes the medullary osmotic gradient
Board Review…
What mainly controls Na+ reabsorption? How does ANP/BNP affect reabsorption?
How do AngII and Aldosterone increase Na+ reabsorption?
How does ANP/BNP regulate Na+ transport?
What happens during a hemmorhage?
What factors increase/decrease sodium excretion?
How does the RAAS system control K+ excretion/reabsorption?
How does an increase in K+ not result in hyperkalemia, independent of the RAAS system?
What determines the [K+]ICF -vs- [K+]ECF?
How does an ↑Plasma K+ lead to ↑K+ secretion/excretion?
What does an ↑ Flow do to distal nephron principal cells?
What factors regulate how much K+ is excreted?
How do early diuretics = ↑K+ & NaCl secretion/excretion?
Hormonal Regulation:
Practice Problems
Hormonal Regulation:
Practice Problems
Hormonal Regulation:
Practice Problems
Hormonal Regulation:
Practice Problems
Hormonal Regulation:
Practice Problems
Hormonal Regulation:
Practice Problems
What are three factors that stimulate potassium secretion by the principal cells?
- Increased extracellular fluid potassium concentration
- Increased aldosterone
- Increased tubular flow rate
What is one factor that decreases potassium secretion?
Increased hydrogen ion concentration (acidosis)
Increased dietary potassium intake and increased extracellular fluid potassium concentration stimulate potassium secretion by what four mechanisms?
- Na+/K+ ATPase is stimulated increasing potassium uptake across the basolateral membrane which ultimately makes its way across the luminal membrane into the tubule
- Increased extracellular K+ increases the potassium gradient from the renal interstitial fluid to the interior of the epithelial cell, which reduces backleakage of K+ from the inside of the cells through the basolateral membrane
- Increased K+ intake stimulates more potassium channels from the cytosol to luminal membrane, increasing K+ diffusion
- Aldosterone is stimulated by the adrenal cortex, which further stimulates K+ secretion
If renal clearance is greater than the GFR, that implies there must be __________ of that substance
secretion
