# FCU_ExcitationContraction_Coupling

### About this Functional Cell Unit

This model is a Functional Cell Unit for excitation-contraction coupling in the cardiac cell.

This is a composite module, composed of several individual modules, and merged together in a modular fashion.

INPUTS:

- Stimulus current or action potential.
OUTPUTS:

- Change in number of myosin binding sites on cross-bridges.

### Model status

The current CellML implementation compiles in OpenCOR.

### Model overview

All components are presented in bond-graph form. Components are made by converting an existing kinetic model and translating into bond-graph form.

A description of the process to find bond-graph parameter is shown in the folder parameter_finder, which relies on the:

- stoichiometry of system
- kinetic constants for forward/reverse reactions

- If not already, all reactions are made reversible by assigning a small value to the reverse direction.

- linear algebra script, which outputs the bond-graph parameters K and
*κ*.

Here, this solve process is performed in Python.

### Modular description

#### Components

CellML divides the mathematical model into distinct components, which are able to be re-used in other composite models. These CellML components are:

- Sarcoplasmic/endoplasmic Ca2+ ATPase (SERCA)
- Phospholamban regulation (PLB)
- Ryanodine receptor (RyR)
- L-type calcium channel (LCC)
- Troponin-C (TnC)

Source | Components |
---|---|

Saucerman et al. (2003) | PLB |

Luo and Rudy (1994) | LCC |

Tran et al. (2009) | SERCA |

Stern et al. (1999) | RyR |

Niederer et al. (2006) | TRPN (TnC) |

Each of these blocks is itself a CellML model, complete with bond-graph parameters appropriate for the isolated system.