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. Author manuscript; available in PMC: 2014 Oct 2.
Published in final edited form as: Math Biosci. 2012 Oct 6;241(1):56–74. doi: 10.1016/j.mbs.2012.09.003

Figure 1.

Figure 1

Compartmental model of the cardiovascular and respiratory circulations. Systemic (subscript S), brain (subscript B), and pulmonary (subscript P) arteries (subscript a) and veins (subscript ν); Vessels carrying oxygenated blood (systemic arteries and pulmonary veins) are red, while vessels carrying deoxygenated blood (systemic veins and pulmonary arteries) are blue. All vascular compartments represent a group of vessels with similar pressure p [mmHg]. Each vascular compartment is characterized by its volume V [ml] and compliance C [ml/mmHg]. The left (red, subscript lν) and right (blue, subscript rν) ventricles generate pulsatile pressure plν, prν [mmHg]. These two compartments are defined using time-varying elastance E [mmHg/ml]. Flow q [ml/s] between compartments are opposed by constant resistances [mmHg s/ml]. Gases diffuse from major arteries into the capillaries at a rate D. Tissue compartments (yellow) account for exchange of gases (O2 and CO2) with capillaries. Each vascular bed is characterized by a metabolic rate M [mlstpd/s], and the gas concentrations in the tissues and capillaries are denoted by c [mlstpd/ml]. The lungs are represented by three dead space compartments each predicting the partial pressure of the gases pDi,g [mmHg]. The partial pressure of the gases in the inspired air pI,g, and the CO2 expiratory partial pressure pexp,CO2 are marked separately.