Reabsorption And Secretion Flashcards
What are the different types of transport mechanisms in the Kidney?
- Simple Diffusion: down concentration gradient, no protein nor energy
- Facilitated Diffusion: down concentration gradient, PROTEIN NEEDED, no ATP.
- Active Transport: AGAINST concentration gradient, PROTEIN and ATP needed
Different types of PROTEIN MEDIATED TRANSPORT?
- Uniport: one molecule crosses the membrane. (Facilitated diffusion)
- Symport or Cotransport: 2 or more molecules cross membrane in same direction.
- Antiport or Countertransport: 2 or more molecules move on opposite directions
What is Transport Maximum?
- Maximal rate of transport for a substance when its transport protein is fully saturated
What is the only way to ⬆️TM?
- ⬆️Transport proteins
What is primary transport?
- Active transport in which ATP is involved directly in the transport of a molecule.
Na+-K+ -ATPase
What is secondary transport?
- Active transport in which ATP is involved indirectly in the movement of a molecule across the membrane.
EXAMPLE: Na+K+ATPase necessary for NA+Glucose Contransport or Na+H+ Contratransport
These substance have an equal Filtration Load = Excretion Rate?
- Inulin
2. Mannitol
How do you calculate the Filtration Load?
Filtration Load= GFR x Px
Px= free concentration of substance in plasma (mg/ml)
How do you calculate Excretion Rate?
Excretion Rate= (Ux)(V)
Ux= urine concentration V= urine flow rate
What is clearance?
The removal of a substance per volume of plasma per unit of time
How is Renal Clearance Calculated?
Renal Clearance= (Ux)(V)/ Px
What limits Glucose Reabsorption?
TM for glucose.
⬆️Glucose concentration—> TM —> ⬆️Glucose excretion
Excellent marker for TM secretion?
- P-aminohippuric acid (PAH) secretion
Percentage of PAH that is always filtered vs secreted?
- Filtered: 20%
2. Secreted: 80%
PAH is an excellent marker for ?
ERPF
(Effective Renal Plasma Flow)
Kidney Blood Flow that DOES NOT go to the glomerulus
How do you calculate RBF?
RBF= RPF/1-Hct
If 100% of PAH is excreted by the Kidneys, ERPF must equal what?
Renal clearance for PAH.
EPRF= Urinary Concentration PAH x V/Plasma concentration PAH = Clearance PAH
Drugs competing for same Organic Anion Transporter? (OAT)
FAPS
- Furosemide
- Acetazolamide
- Penicillin
- Salicylate
Drugs that compete with same Organic Cation Transporter? (OCT)
CAMPA
- Cimetidine
- Amiloride
- Morphine
- Procainamide
- Atropine
Useful substance to calculate GFR?
Inuline
