The Vena Cava ("heart's veins")Below is the subsystem that solves the equations for the vena cava.
Physiological notes: Figure 1. Simulink block diagram of the vena cava.
Simulation notes:
- Input resistance is considered to be the outlet resistance of the arms, head, trunk, and legs.
- Output resistance is set equal to the input resistance of the right ventricle.
- It is assumed that there is no net heat gain or loss of heat.
- The weight of the vena cava is roughly equivalent to the volume of blood, V, that it contains.
- Switch blocks ("Pick Blood Flow" and "Pick Heat Flow") are used to select specific channels from the combined blood and heat flow vectors coming from the systemic subsystems. Blood flow data is pulled off of channels 1,3,5, and 7; while heat flow data comes from channels 2,4,6 and 8.
- A new Elementary Math block (1/U) is used to take the reciprocal of V9.
- The Goto and From blocks P9 and F1i are connections to other circulatory systems where the information flow is opposite of blood flow. Using the Goto and From blocks for these connections allows the connections to be made "below the surface", thereby keeping the main block diagram uncluttered and less confusing.
- The Goto block V9 allows key output information to be passed directly to the Analysis Subsystem, where it can be managed in one central location.
- The line labels are used to keep track of variable information, making the flow of information easier to track.
