Renal Physiology Pt. 2 (Final Exam) Flashcards
What names are given for the cell side that is in contact with the urinary lumen?
- Apical / Tubular / Luminal Side
What is the name given for the side of the cell that is in contact with the interstitium?
- Interstitial Side
What is transcellular reabsorption?
Reabsorption occurring through the cell
What is paracellular reabsorption?
Reabsorption occurring in-between cells
What mechanism drives the processes of transcellular reabsorption?
- Na⁺ gradient with Secondary Active Transport.
What are the most important transporters in the Proximal Convoluted Tubule?
- Na⁺/Glucose Symporter
- Na⁺/AminoAcid Symporter
- Na⁺/H⁺ Antiporter
What ion is reabsorbed by following Na⁺?
By what route is this ion reabsorbed?
- Cl⁻
- Paracellular Pathway
What molecule follows Na⁺ & Cl⁻ ?
H₂O
Movement of _______ is always passive.
water
What is bulk flow?
- The flow of H₂O and dissolved substances.
What is the Vᵣₘ of tubular epithelial cells?
- -70mV
What is the brush border?
Where is it located?
What is its purpose?
- Projections out of tubular epithelial cells
- Located on the tubular lumen side.
- ↑ surface area
What anatomical component prevents H₂O and electrolyte permeability in between cells?
How does this compare in the proximal tubule?
- Tight junctions
- Less tight in the PCT.
What is needed for Ca⁺⁺ and Mg⁺⁺ reabsorption?
- Positively charged urinary lumen
How much reabsorption of filtrate occurs in the Proximal Tubule?
What is secreted here?
- 2/3
- H⁺, organic acids/bases
What two molecules, spoken about in lecture, are highly absorbed in the PCT?
What molecule has no reabsorption in the PCT?
What would occur with this molecule’s luminal concentration as it moves along the tube?
- Glucose & amino acids
- Creatinine; concentration would increase as the fluid moves down the PCT.
Where does secretion of organic anions & cations occur?
Via what transporters?
- PCT
- OAT’s & OCT’s
What section of the nephron is primarily responsible for pH regulation?
- PCT
Which transporter is the SGLT?
What does SGLT stand for?
- Na⁺/Glucose Cotransporter
- Sodium/Glucose Transport Protein
What is the name for the antiporter that moves H⁺s in the PCT?
- NHE (Sodium/Hydrogen Exchanger)
Where are the SGLT, NHE & Na⁺/AA symporter transporters located?
- Apical lumen of the PCT.
What would you expect the ICF concentration of glucose to be in a tubular cell with a healthy SGLT?
- High Concentration of glucose in the ICF.
What GLUT transporter is located in the
S1 segment of the Proximal tubular cells?
What side is this located on?
How does this move glucose and to where?
- GLUT-2
- Interstitial side
- Glucose moved to interstitium via facilitated diffusion. (down its concentration gradient)
How much paracellular movement of glucose occurs in the Proximal Tubule? Why?
- None. Glucose is too big to move paracellularly.
What ratio of Na⁺/Glucose is reabsorbed via SGLT2 in the S1 segment of the Proximal Tubule?
1:1
What ratio of Na⁺/Glucose is reabsorbed via SGLT1 in the S2/S3 segments of the Proximal Tubule?
2Na⁺ : 1Glucose
What occurs with Na⁺ reabsorption when a patient is severely hyperglycemic?
- Na⁺ reabsorption increases (due to co-transporter nature)
What is the mechanism behind a chronically increased GFR with chronic hyperglycemia?
- ↑Gl reabsorption = ↑Na⁺ reabsorption
- Less Na⁺ downstream for Macula Densa.
- MD thinks GFR is low and dilates afferent arteriole & constricts efferent arteriole.
What occurs long term to nephrons with hyperglycemia?
What would help prevent this damage?
- Nephron damage from chronically increased GFR from hyperglycemia.
- ACE Inhibitors or ARBs.
What percentage of glucose reabsorption occurs via the S1 segment of the PCT?
What GLUT transporter is used here?
What sodium/glucose transporter is used on the S1 segment?
- 90%
- GLUT-2
- SGLT2
What GLUT transporter is located in the
S2/S3 segment of the Proximal tubular cells?
How much of glucose reabsorption occurs here?
What sodium/glucose transporter is used in the S2/S3 segments?
- GLUT-1
- 10%
- SGLT1
What drug inhibits the NHE?
What are the effects of this?
- Acetazolamide
- ↓Na⁺ reabsorption = H₂O loss & ↓BP.
Where does the majority of urea management occur?
Besides this, what other areas manage urea?
-Medullary Collecting Duct via ADH
- Proximal Tubule
What enzyme would facilitate the process in the figure below?
- Carbonic Anhydrase (CA)
Each HCO₃⁻ reabsorbed or produced means less _____.
H⁺
What serum glucose is considered normal for A&P class?
At what serum glucose do we exceed to the ability of the kidney to completely reabsorb all filtered glucose?
- 100mg/dL
- 200mg/dL
At what serum glucose do we meet our transport maximum?
What does this mean?
- 375mg/dL
- All glucose past this serum level is excreted.
How is filtered load calculated? Give an example with glucose.
Filtered Load = VFF (volume of filtered fluid) · [substance]
FL = 1.25dL/min · [100mg/dL glucose]
Filtered Load = 125mg/min
Long-term use of SGLT Inhibitors would have what effect on one’s weight?
- Weight loss would occur
What would SGLT Inhibitors do the glucose transport max and the glucose threshold?
- ↓ Transport max
- ↓ Threshold
Are SGLT Inhibitors natriuretics? Why or why not?
- Yes; Block Na⁺ & Glucose reabsorption = more Na⁺ later in tube with H₂O following.