Flashcards in Reabsorption/Secretion in the Proximal Tubule - Rao Deck (30):
How many times is entire plasma filtered through glomerulus every day?
60 times = 5 times whole body fluid
What is the equation for rate of flow into the loop of Henle?
Vl = GFR * P in / TF in
What is the tonicity of reabsorption in the proximal tubule?
What is reabsorbed in the proximal tubule?
What is secreted in the proximal tubule?
Organic acids and bases
How is sodium reabsorbed in the PT?
*Basolateral Na K ATPase
*Luminal Na channel (secondary active)
What is reabsorbed via Na cotransporters in the PT?
What is reabsorbed via Na antiporters in the PT?
How is water reabsorbed in the PT?
Osmotic gradient through leaky epithelium
How is bicarbonate reabsorbed in the PT?
*HCO3 + H -> H2CO3 via CA -> H2O + CO2
*CO2 -> ISF
*H2O + CO2 via CA -> H2CO3 -> H + HCO3
*HCO3 -> ISF via Na / HCO3 cotransport (basolateral)
*H -> lumen via Na / H antiport (luminal)
How is glucose reabsorbed in the PT?
Na / Glucose cotransport (apical)
What is the threshold level of glucose reabsorption?
What is the transport maximum of glucose reabsorption?
What does glucosuria cause?
What causes glucosuria?
Pregnancy (lactose and galactose excretion)
Mutation in SGLT1/2 (glucose cotransporters)
How are amino acids reabsorbed in the PT?
Na / amino acid cotransport (apical)
How much glucose is typically reabsorbed?
What percentage of amino acids are typically excreted?
How are organic acids (Krebs cycle intermediates) reabsorbed in the PT?
Na / organic acid cotransport
What could condition could overwhelm reabsorption capacity of organic acids?
What conditions have high protein excretion?
How is phosphate reabsorbed in the PT?
Coupled to Na electrochemical gradient
What is the threshold of phosphate reabsorption?
Normal plasma [phosphate] (2.5-4.5 mg/dL)
What is the transport maximum of phosphate regulated by?
PTH - decrease Tm
How is chloride reabsorbed in the PT?
Passive transport (water and Na gradients)
Is chloride or bicarbonate preferentially reabsorbed in the PT?
How is potassium reabsorbed in the PT?
Passive transport along concentration gradient through permeant epithelium
How is urea reabsorbed in the PT?
Passive transport (slow - 50% reabsorbed)
What is the clinical significance of substances that are freely filtered but not reabsorbed? (Poorly permeant solutes)
Reduction of intracranial and intraocular pressure
Promote excretion of toxins