China
Africa
Explore chapters and articles related to this topic
Gastrointestinal tract and salivary glands
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The large intestine is approximately 1.5 m long from caecum to anus, with a variable calibre from between 9 and 3 cm. It lies peripheral to the small intestine, with the more lateral structures being relatively fixed in position. From the right iliac fossa where the terminal ileum communicates via the ileo-caecal valve, the ceacum extends superiorly as the ascending colon before it turns abruptly to the left, beneath the liver, at the hepatic flexure. Crossing the abdomen, the transverse colon turns inferiorly at the splenic flexure, where it continues as the descending colon. The bowel loops to a variable degree at the sigmoid colon, passing along the posterior wall of the pelvis where it merges with the rectum at the recto-sigmoid junction. The rectum is 13 cm long and is a dilated part of the large intestine, continuous with the anal canal and anus. The large intestine displays large sacculations known as haustra that are thought to slow the passage of digested matter. The relations of the large intestine are complex and variable as the bowel traverses the different regions of the abdomen (Figs 5.52a–c).
Application of SPH to Single and Multiphase Geophysical, Biophysical and Industrial Fluid Flows
Published in International Journal of Computational Fluid Dynamics, 2021
Paul W. Cleary, Simon M. Harrison, Matt D. Sinnott, Gerald G. Pereira, Mahesh Prakash, Raymond C. Z. Cohen, Murray Rudman, Nick Stokes
The SPH boundary particles that comprise the taenia coli are shown coloured blue in Figure 10. The haustra and folds are dynamic structures formed by active contraction and relaxation of circular muscle. We assume for this model that the entire thin SPH geometry consists of circular muscle. This circular muscle is represented by spring forces applied between adjacent particles in both circumferential and axial directions. This allows us to consider each thin axial slice of the colon wall as separate rings of circular muscle that can actively contract or relax independently to the rest of the colon. Tension in the bands of longitudinal muscle bunch the colon wall to form the haustra and give the semilunar folds their familiar and distinctive quasi-triangular profile (as shown in Figure 10). The colon model is completely filled with a Newtonian digesta with a representative viscosity of 0.01 Pa·s and a density of 1000 kg/m3. The inflation of the haustral compartments (to form the familiar haustral bulges) is thus a direct model prediction of fluid pressures pushing outward against the walls.