Renal 2 Flashcards
Do we lose more K or Na? And why?
K because the kidneys has to exchange K to reabsorbed Na and then try to recapture the K
Reabsorption and secretion of urea helps with what?
Reabsorb or lose water respectively
What 2 molecules are reabsorbed the least?
K and urea
What is the equation for excretion?
Filtration-reabsorption+secretion
Ability of each successive segment of the proximal tubule to reabsorb a constant fraction of glomerular filtrate and solutes delivered to it is the explanation of what?
Glomerulotubular balance (GTB)
Glomerulotubular balance prevents large swings in what when GFR is high?
In urine volume and washout of the ECFV
Nephron absorbs more of what, relative or absolute amount of filtrate?
Absolute amount
GTB happens because a higher GFR meaning a what pressure?
Higher peritubular capillary oncotic pressure
Proximal tubule has what 3 things occurring there?
- Na/K ATPase
- Na/H exchanger (NHE): Na/HCO3 co-transporter
- Na/glucose transporters (SGLT)
Toxins and drugs are secreted where?
Proximal tubule
AngII stimulates what in the proximal tubule?
Na/H, Na/HCO3, and Na/K pump
Carbonic anyhydrase inhibitors cause what in proximal tubule?
Na and bicarbonate bind in lumen and some is exerted and lose K
How powerful is carbonic anyhydrase inhibitors in proximal tubule?
Moderately
Na/H exchanger (NHE): Na/HCO3 co transporter does what in proximal tubule?
Secretes 80% H and reabsorbs 80% bicarb via CA
SGLT2 inhibitors do what for SGLT in proximal tubule?
Allows kidneys to lower excessive blood glucose b promoting glucosuria
Tubular fluid/plasma concentration =1 means?
[substance] in tubular fluid = [substance] in plasma
-reabsorption of water has occurred at same rate as the substance in PT
Tubular fluid/plasma concentration <1 means?
More substance reabsorbed than water in the PT
Examples of Tubular fluid/plasma concentration <1 (3)
AA
Glucose
HCO3-
Tubular fluid/plasma concentration >1 means?
Substance was not reabsorbed more than water, and/or substance was secretion into the PT
Examples of Tubular fluid/plasma concentration >1 (2)
Urea
Creatinine
What is the point at which increases in concentration of a substance do not result in an increase in movement of a substance across a cell membrane (in kidney this means it will not be reabsorbed and thus excreted)
Transport maximum (Tm or Tmax)
What limits how fast things can be reabsorbed?
Tmax
Tmax is determined by what?
Saturation of a limited number of transporters
What is filtered load equation?
Plasmas [ ] x GFR
Do kidneys normally regulate plasma glucose?
NO
Both limbs of LOH work together to create a concentrated medullary interstitium of?
600-1200 mOsm
Predominant osmoles of LOH?
NaCl and urea
Descending limb of LOH is concentrated or diluted segment?
Concentrated
Descending limb of LOH is permeable to what?
Water
Ascending limb LOH is concentrated or diluted segment?
Diluting
Ascending limb of LOH is permeable to what?
NaCl
Can urea enter both ascending and descending LOH?
Yes
What are the steps of counter current multiplication (6)
- Salt is pumped out of ascending limb
- Increase in interstitial osmolarity
- Water leaves the descending limb
- Increased osmolarity of filtrate in descending limb of the LOH
- Increased osmolarity of filtrate in ascending limb of LOH
- Start back at #1
Where in the nephron is the counter current exchanger?
Vasa recta
What does the counter current exchanger create?
Large osmotic gradient in the nephron and interstitial fluid; water and salts are reabsorbed from the interstitial fluid into the vasa recta and brought back to the body because of this gradient
2 major transporters in thick ascending limb LOB?
- Na/K/Cl (NKCC2)- ~25% into cell to be reabsorbed
2. Na/H anti porter (NHE)- 10% H secreted and HCO3 reabsorbed