Renal Q2 Flashcards
What is the principal mechanism for modifying the composition of the filtered fluid?
Tubular reabsorption
Movement from the lumen into the Peritubular capillary is…
Movement from the Peritubular capillary into the lumen is…
Tubular reabsorption
Tubular secretion
Amount excreted =
Amount filtered (+ secreted) - amount reabsorbed
If amount X excreted
A % of X was reabsorbed
What are 2 examples of substances that are fully reabsorbed?
amount excreted = 0
Glucose
Bicarb
T/F
A homeostatic mechanism is altering the amount of reabsorption of the filtered load
**Are there exceptions to this????
True
What are the 2 membranes of Renal Epithelial cells?
Luminal
Basolateral
What type of transport occurs across both membranes (luminal and basolateral) of renal epithelial cells?
What type of transport occurs between renal epithelial cells across tight junctions by simple diffusion?
What type of transport is most common?
Transcellular
Paracellular
Transcellular
What does the Transcellular route require on both membranes?
Transport proteins
What does Passive Transport require?
favorable electrochemical gradient
Name 4 types of Transport.
Simple diffusion
Ion channels
Facilitated (uniporter, symporter, antiporter)
Energy Dependent (ATPases)
What is the rate limiting step in the reabsorption of sodium (and many other solutes)?
Na/K pump
ATP ase
What is the Glucose transporter of the kidney?
GLUT 2
How does the Collecting tubule transports Sodium out through the Luminal membrane?
Na+ selective channels through luminal side
exits cell via Na/K pumps (ATP powered)
How does the Proximal tubule transport Sodium out through the Luminal membrane?
Na+ crosses lumen via Na+/Glc symporter
exits cell via Na/K pump (ATP powered)
What fraction of glomerular filtrate is reabsorbed by the Proximal Tubule?
2/3
How much water is filtered per day?
How much is reabsorbed at the Proximal Tubule?
180L
120L
How is Glucose reabsorbed in the Proximal Tubule?
Na+ symporter on Luminal side
(Downhill Na+ carries Glc Uphill)
*SGLT-1/SGLT-2 are Na+/Glc cotransporters
GLUT2 (uniporter) on basolateral membrane
What is one of the principal techniques used to assess tubule function?
In vivo micropuncture
What are 2 of the anatomical limitations of In Vivo Micropuncture?
(what can’t the pipette reach)
Collecting tubule
Juxtamedullary nephron
*these aren’t accessible from the surface of the kidney
What 3 solutes are absorbed early in the Proximal Tubule?
Glucose
Amino Acids
Bicarb
What solute is absorbed late in the Proximal Tubule?
Cl-
What is absorbed throughout the entire length of the Proximal Tubule?
Water
The filtration of water and solute at the Lumen of the Proximal Tubule is what type of fluid reabsorption?
Isosmotic