NUMERICAL-SIMULATION OF THE PERISTALTIC REFLEX OF THE SMALL-BOWEL

A mathematical model and results of numerical simulation of the perist altic reflex development of the small bowel are presented. The organ i s modeled as a soft orthotropic cylindrical biological shell, reinforc ed by the smooth muscle elements. Their mechanical activity is under t he control of a simple reflex are represented by a single cholinergic neurone. The dynamical reaction starts as a response to the depolariza tion wave propagating along the smooth muscle layers. The muscle layer s contract independently but in a coordinated way with the generation of active forces. The mechanical properties of the wall are supposed t o be nonlinear. Deformations of the bioshell are finite. The governing system of equations is obtained and solved numerically. The finite-di fference method of second-order accuracy over the time and space varia bles has been used. The dynamics. of stress-strain distribution in the biological shell and shape changes are analyzed. It is shown that the re is no axial symmetry is the organ's deformation during the first (p reliminary) stage of motor reaction. Only with the development of prop ulsive contractions is the symmetry observed.