System of first order differential equations in Simulink

My question is related to a system of differential equations which I am trying to solve using Simulink. More specifically, I am trying to model the human cardiovascular system with a pulsatile heart and control system from the following paper:

(Ursino, M. (1998). Interaction between carotid baroregulation and the pulsating heart: A mathematical model. American Journal of Physiology - Heart and Circulatory Physiology, 275(5 44-5), 1733–1747. https://doi.org/10.1152/ajpheart.1998.275.5.h1733)

I want to make sure that how I interpreted the formulas into Simulink is correct or not. The pressure in the left atrium (la) is given with the following formula:

Which I simulated in Simulink like:

The Saturation has an upper limit of 10000 and lower limit of 0. I did not change the block parameters of the integrator. I am solving this in ode23t.

My Simulink model is currently not working and I can't seem to figure out why, and thus need first the confirmation weather I am modelling the formulas correct or not.

Also, does anyone have a good resource for me to understand this type of system of differential equations?

Thank you!

Answer 1

[Sulaymon Eshkabilov]

There are a couple of errs made in your model with the feedback and summing junction.

Here is the corrected model view. You'd need assign input signals for Ppv and Fi,l, and initial condition in the intergrator block. And you'd need to set up saturation block settings.

[Femke Cappon]

So why did you seperate the summation?