Reabsorption and Secretion - Bishop's Notes Flashcards
Filtered load =
Filtered load = glomerular filtration rate (GFR) x plasma concentration ([P]x)
Excretion rate =
Excretion rate = Volume (over a measured time period) x urine concentration ([U]x)
Reabsorption/Secretion =
Filtered Load - Excretion Rate What’s going into Bowman’s space minus what leaves in the urine.
There is net ______ of Na+
reabsorption
There is net ______ of PAH
secretion
What is paracellular transport?
Transfer of substances across an epithelium by passing through the intercellular space between the cells.
What is transcellular transport?
Substances travel through the cell, passing through both the apical membrane and basolateral membrane.
Transcellular reabsorption of glucose uses what transporters?
From lumen: Na+ and glucose cotransporter From blood: Na+/K+ antiporter and glucose passes into blood
What is the transport maximum (Tm)?
Max amount of a substance that can be reabsorbed (or secreted). Exceeding it causes substance to “spill” into the urine (or remain in plasma).
What is glucose “splay”?
Glucose appears in urine before Tm is reached. Due to low affinity and heterogeneity of transporters.
What can cause glucosuria?
- Diabetes mellitus: elevated glucose levels - Pregnancy: increase in GFR, filtered load may surpass reabsorptive capacity - Abnormalities of Na+/glucose transporter: can lower Tm
Urea is reabsorbed via _______.
Passive reabsorption.
List anions secreted by the proximal tubule.
- cAMP - Bile salts - Hippurates - Oxalate - Prostaglandins - Urate
List cations secreted by the proximal tubule.
- Creatinine - Dopamine - Epinephrine - Norepinephrine
What is the equation for renal clearance?
C = (U x V) / P Clearance is the urinary excretion rate over the (original) plasma concentration.
What is does the graph of clearance vs. plasma concentration look like for PAH, glucose, and inulin?
