Glomerulus
This layer of the glomerular filtration barrier contains fenestrations that allow passage of water and solutes but block red blood cells.
What is the glomerular endothelium?
These apical structures increase surface area for reabsorption in the PCT.
What are microvilli (brush border)?
This limb is permeable to water but not solutes.
What is the thin descending limb?
This early DCT cotransporter moves Na+ and Cl− into the cell.
What is the Na‑Cl cotransporter (NCC)?
This substance has a clearance equal to GFR because it is freely filtered and neither reabsorbed nor secreted.
What is inulin?
What is creatinine?
This pressure increases when the afferent arteriole dilates, resulting in an increased GFR.
What is glomerular hydrostatic pressure?
This cotransporter uses the sodium gradient to move glucose into PCT cells.
What is the SGLT (Na‑glucose cotransporter)?
This limb is impermeable to water and urea.
What is the ascending limb?
This hormone increases Ca++ reabsorption in the early DCT.
What is parathyroid hormone (PTH)?
Glucose begins appearing in urine when plasma levels exceed this approximate threshold.
What is ~200 mg/dL?
A kidney stone lodged in the ureter increases this pressure, reducing GFR.
What is Bowman’s space hydrostatic pressure?
This enzyme catalyzes the conversion of carbonic acid into CO₂ and H₂O in the tubular lumen.
What is carbonic anhydrase?
This transporter in the thick ascending limb moves Na+, K+, and 2 Cl− into the cell.
What is the Na‑K‑2Cl cotransporter (NKCC2)?
Principal cells respond to this hormone by increasing Na+ reabsorption and K+ secretion.
What is aldosterone?
This organic acid is 90% cleared from plasma and is used to estimate renal plasma flow.
What is PAH (para‑aminohippuric acid)?
High levels of this hormone constrict both afferent and efferent arterioles equally, lowering GFR.
What is angiotensin II?
This pump on the basolateral membrane maintains low intracellular sodium, enabling continued Na+ entry from the lumen.
What is the Na+/K+ ATPase?
The mechanism that creates the medullary osmotic gradient using the loop of Henle is called this.
What is countercurrent multiplication?
ADH increases water reabsorption by inserting this specific protein into the apical membrane.
What is aquaporin‑2 (AQP2)?
About what percentage of filtered urea is passively reabsorbed in the PCT?
What is 50%?
Name the three layers of the glomerular filtration barrier in correct order from blood to Bowman’s space.
What are endothelium → basement membrane → podocyte epithelium?
Breakdown of glutamine in PCT cells produces two key products: one is secreted, one is reabsorbed. Name both.
What are NH4+ (secreted) and HCO3− (reabsorbed)?
At the bend of the loop of Henle, tubular fluid reaches this approximate osmolarity.
What is 1200 mOsm/L?
Alpha‑intercalated cells use this ATP‑dependent pump to secrete H+ in exchange for K+.
What is the H+/K+ ATPase?
Under ADH, urea exits the collecting duct via this transporter, contributing significantly to medullary osmolarity.
What is UT‑A1?