FIGURE 2.

PBPK model schematic for nicotine showing the representation of the main organs considered with various sub-compartments in the lung for inhalation exposure. QL, QRb, QC, QTB, and QURT refer to blood flow to each tissue compartment. QP refers to the alveolar ventilation rate. Cv refers to the venous concentration and CI to the inhaled vapor concentration. F1, F2, and F3 refer to the fraction deposited in each region of the respiratory tract. In the respiratory tract (URT, bronchial and alveolar), the light purple represents the mucus and epithelium, and the dark purple represents the submucosa region where blood perfusion occurs.