%0 Journal Article
%T A two-layered mechanical model of the rat esophagus. Experiment and theory
%A Yanhua Fan
%A Hans Gregersen
%A Ghassan S Kassab
%J BioMedical Engineering OnLine
%D 2004
%I BioMed Central
%R 10.1186/1475-925x-3-40
%X Inflation experiments were done at in vivo length and pressure-diameters relations were recorded for the rat esophagus. Furthermore, the zero-stress state was taken into consideration.The radius and the strain increased as function of pressure in the intact as well as in the individual layers of the esophagus. At pressures higher than 1.5 cmH2O the muscle layer had a larger radius and strain than the mucosa-submucosa layer. The strain for the intact esophagus and for the muscle layer was negative at low pressures indicating the presence of residual strains in the tissue. The stress-strain curve for the submucosa-mucosa layer was shifted to the left of the curves for the muscle layer and for the intact esophagus at strains higher than 0.3. The tangent modulus was highest in the submucosa-mucosa layer, indicating that the submucosa-mucosa has the highest stiffness. A good agreement was found between the measured elastic modulus of the intact esophagus and the elastic modulus computed from the elastic moduli of the two separated layers.The majority of previous mechanical studies on visceral organs, including the blood vessels, have considered them as homogenous tubes; i.e., a single layer structure. Most visceral organs are, however, multilayered, e.g. the arteries consist of intima, media and adventitia and the gastrointestinal tract has circumferential and longitudinal muscle layers, submucosa and mucosa layers.The esophagus represents a very interesting biomechanical model since it is the only organ that can be separated into two layers without damage to either layer. Hence, the muscle layers can be separated from the mucosa-submucosa layer by dissection, leaving two intact tubes. Separation experiments of the esophagus in guinea pigs and rabbits showed that the submucosa-mucosa layer had larger residual strains and opening angles than the muscle layer [1-3]. Considering the multi-layered composite structure and the difference in zero-stress state between the layers
%K Biomechanics
%K Mucosa-submucosa layer
%K Muscle layer
%K Opening angle
%K Zero-stress state
%U http://www.biomedical-engineering-online.com/content/3/1/40