Guyton, Non-Muscle Blood Flow, 2008

Model Status

This CellML model has been validated. Due to the differences between procedural code (in this case C-code) and declarative languages (CellML), some aspects of the original model were not able to be encapsulated by the CellML model (such as the damping of variables). This may effect the transient behaviour of the model, however the steady-state behaviour would remain the same. The equations in this file and the steady-state output from the model conform to the results from the MODSIM program.

Model Structure

Arthur Guyton (1919-2003) was an American physiologist who became famous for his 1950s experiments in which he studied the physiology of cardiac output and its relationship with the peripheral circulation. The results of these experiments challenged the conventional wisdom that it was the heart itself that controlled cardiac output. Instead Guyton demonstrated that it was the need of the body tissues for oxygen which was the real regulator of cardiac output. The "Guyton Curves" describe the relationship between right atrial pressures and cardiac output, and they form a foundation for understanding the physiology of circulation.

The Guyton model of fluid, electrolyte, and circulatory regulation is an extensive mathematical model of human circulatory physiology, capable of simulating a variety of experimental conditions, and contains a number of linked subsystems relating to circulation and its neuroendocrine control.

This is a CellML translation of the Guyton model of the regulation of the circulatory system. The complete model consists of separate modules each of which characterise a separate physiological subsystems. The Circulation Dynamics is the primary system, to which other modules/blocks are connected. The other modules characterise the dynamics of the kidney, electrolytes and cell water, thirst and drinking, hormone regulation, autonomic regulation, cardiovascular system etc, and these feedback on the central circulation model. The CellML code in these modules is based on the C code from the programme C-MODSIM created by Dr Jean-Pierre Montani.

The circulatory system is divided into three separate parts for blood flow control:(1) the kidneys which are presented in an entirely separate CellML model; (2) non-muscle local blood flow control; and (3) muscle local blood flow control. This particular CellML model describes non-muscle autoregulatory local blood flow control. This portion of the circulation has three separate parallel autoregulatory processes, one of which occurs in a matter of minutes, another over a period of tens of minutes, and a third over a period of weeks. All of these are considered to respond to changes in tissue oxygen level. The first two are rapid metabolic feedback effects, one almost instantaneous and the other occurring over a period of tens of minutes to an hour or so. The third is considered to be structural changes that result over a period of weeks and may be a consequence of the vasodilation or vasoconstriction that occurs during the two short-term metabolic stages.

A systems analysis diagram for the full Guyton model describing circulation regulation.
A schematic diagram of the components and processes described in the current CellML model.

There are several publications referring to the Guyton model. One of these papers is cited below:

Circulation: Overall Regulation, A.C. Guyton, T.G. Coleman, and H.J. Granger, 1972, Annual Review of Physiology , 34, 13-44. PubMed ID: 4334846

Derived from workspace Guyton, Non, Muscle, Blood, Flow, Control, 2008 at changeset fa79587edd44.
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