Saturation and renal threshold and excretion

Saturation

fastest rate of transport when all careers are occupied with a substrate

Once saturation occurs

then transport reaches a maximum

Renal threshold

plasma concentration of substrates when transport maximum occurs

Excretion =

Excretion = filtration - reabsorption + secretion

Clearance

• rate at which a solute disappears from the body by excretion or by metabolism

• Clearance is a noninvasive way to measure GFR (125 ml/min)

• Expressed as a volume of plasma (ml plasma/min) cleared of substance, not how much X has been excreted

Clearance of X =

Clearance of X = excretion rate of X (mg/min)/ [X]plasma (mg/ml plasma)

• Set this up as a proportion, to cancel mg → mg/ml plasma