Proximal tubule regulation Flashcards
Should glucose appear in urine?
When will glucose appear in urine?
Not normal
If channels and transporters reached saturation
What is absorbed quicker Glucose and AA or bicarb?
Glucose and AA
What state is urine at end of tubule?
Isotonic
If urine is isotonic what occurs Na+?
Stay lvl as flows osmotically
Do Na+ lvls change at start to end?
No- isotonic
Na+ follows water
Is insulin absorbed?
No- freely filtered
What will happen to lvls of insulin?
Amount in=Amount out
Same GFR
What 2 things can be used to measure GFR?
Why?
Creatine
Insulin
Both freely filtered
What is used as measure for renal plasma flow?
Why?
Paraminohippuric acid (PAH)
Actively secreted, freely filrters, not reabsorbed
Any in renal plasma excreted and cleared
Define renal clearance?
Volume of plasma cleared of a substance in a given time (mL/min)
State renal clearance for sodium, albumin, penicillin, urea
Albumin clearance = 0
Sodium clearance = low (freely filtered but lots of reabsorption)
Penicillin clearance = higher than GFR (actively secreted)
Urea clearance = high (excreted about 40% of what goes into the kidney)
Define tubular reabsorption and tubular secretion?
Tubular reabsorption: movement from tubular lumen to peritubular capillaries
Tubular secretion: movement from peritubular capillaries to tubular lumen
Filtrates composition altered by movement to and from tubules to the peritubular capillaries
What increases reabsorption?
Greater filtration fraction- high blood volume
Increas osmotic pressure
State equation for clearance?
Clearance = amount filtered at glomerulus - amount reabsorbed + amount secreted
State equation for renal plasma flow?
Renal plasma flow = clearance x (1 / haematocrit)
