Symbol | Definition |
---|---|
C p | Numerical concentration of platelets in the blood |
C s | Amount of 5-HT per platelet (platelet 5-HT concentration) |
D | Diffusion coefficient of 5-HT diffusion from the gut wall into gut blood capillaries |
d b | Rate constant of 5-HT influx into the blood due to 5-HT diffusion from the gut |
d g | Rate constant of 5-HT loss in the gut due to 5-HT diffusion into the blood |
F = F(t) | Flow of free 5-HT in the aorta as a function of time |
| Steady-state flow of free 5-HT in the aorta |
G 0 | Theoretical concentration of extracellular 5-HT in the gut wall around which the control of gut 5-HT release is near-linear |
G = G(t) | Extracellular 5-HT concentration in the gut wall as a function of time |
| Steady-state extracellular 5-HT concentration in the gut wall |
k g | 5-HT uptake rate constant in the gut wall |
k p | 5-HT uptake rate constant in blood platelets |
N tot | Total number of platelets |
R 0 | Theoretical, steady-state gut 5-HT release rate achieved when Îħ = β = 0 |
R = R(t) | Gut 5-HT release rate as a function of time |
| Steady-state gut 5-HT release rate |
P 0 | Theoretical 5-HT concentration in blood platelets around which the control of gut 5-HT release is near-linear |
| Steady-state platelet 5-HT concentration |
S | Total surface of the blood capillaries in the gut wall |
Q tot | Total cardiac output |
t | Time |
t 1/2 | Half-life of blood platelets |
| 5-HT uptake rate of an "average" blood platelet |
T | Period of blood circulation |
w | Wall thickness of gut capillaries |
z g | Proportion of cardiac output routed to the gut and/or liver |
z ng | Proportion of cardiac output not routed to the gut and/or liver |
Îħ | Gain of the gut 5-HT release control that monitors the extracellular 5-HT concentration in the gut wall |
β | Gain of the gut 5-HT release control that monitors the 5-HT concentration in platelets |
γ | SERT activity |
θ h | 1- proportion of free 5-HT cleared by the liver in one blood circulation cycle (Fig. 1) |
θ p | 1- proportion of free 5-HT cleared by the lungs in one blood circulation cycle (Fig. 1) |
θ v | 1- proportion of free 5-HT cleared by the vascular beds of the "non-gut" system (Fig. 1) |
Ï | Surface area of blood capillaries per unit volume of the gut wall |
Ï | Proportion of blood volume not occupied by cells |
Ï | Time constant of the decay of platelet numbers due to their aging |
Îİ b | Total volume of circulating blood |
Îİ g | Total volume of the gut wall |