Renal Reabsorption Flashcards
Where does filtration take place?
Bowmans capsule
Only about _____ liters of the 150-200 liters of filtrate is excreted as urine, the rest (~ 99%) is reabsorbed into the blood.
1 - 2
Nephrons must reabsorb ~ _____% of the filtrate
99
The proximal convoluted tubule (PCT) reabsorbs ______% of most filtered substances
50-100
The proximal convoluted tubule (PCT) reabsorbs:
Nutritionally important molecules
Solutes by active & passive processes
water by osmosis
small proteins by digestion and/or pinocytosis
________ Transport across the kidney tubule occurs mainly via a variety of channels and transport proteins in the renal tubule cell plasma membranes
Transcellular Transport
Transcellular transport proteins are often exclusively localized to either the _____ or the _____ surface of the tubule cell
apical
basolateral
________ Transport may also occur across the tight junctions between the tubule cells
Paracellular
Paracellular transport will be influenced by the permeability of the _____ _____, limited surface area and the electrical and chemical gradients across the tubule (filtrate versus extracellular fluid)
tight junctions
Where does most Na+ reabsorption take place?
PCT
Sodium Reabsorption in: PCT Ascending Loop DCT Principle cells of late distal tubule and collecting duct
65%
20-30%
5%
1-4%
Principle cells of the late DCT & collecting duct: ~1-4% Na+ reabsorbed (stimulated by ________)
aldosterone (increases blood pressure by increasing water reabsorption)
Aldosterone acts on the cells of the ____ nephron.
distal
Na+ / K+ ATPase pump is localized to the _____ membrane of the nephron epithelial cells
basolateral
Sodium-dependent Secondary Active Transport:
Symport Carriers
Na-glucose (SGLUT & SGLUT1) NA-Amino Acids Na-K-@Cl Na-Cl Na-HCO3-
Sodium-dependent Secondary Active Transport:
Antiport Carriers
Na+-H+ (proximal tubules)
Na+-Ca++
The _____ _______ group of membrane transport proteins has over 300 members organized into 47 families and includes a variety of facilitative transporters and secondary active transporters
Solute Carrier (SLC)
Solute Carrier series does not include members of transport protein families which have previously been classified by other widely accepted nomenclature systems including:
primary active transporters such as ABC (ATP Binding Cassette) transporters
ion channels
aquaporins (water channels)
high H+; low pH
Acidosis
low H+; high pH
Alkalosis
high Na+
Hypernatremia
low Na+
Hyponatremia
high K+
Hyperkalemia
low K+
Hypokalemia