Figure 1. Schematic diagram of the modified two-compartment model with impulse residue function for glomerular filtration.

A is the vascular compartment includes intrarenal arteries and glomerular vessels, and T is the tubules compartment. The retention function R_A and R_T in compartment A and T (represented in solid arrow within the box) are the convolution of the input and each impulse residue function. Dashed lines denote the outflow of each compartment and the outflow of compartment A partially flows into compartment T.