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Biokinetic Models
Published in Shaheen A. Dewji, Nolan E. Hertel, Advanced Radiation Protection Dosimetry, 2019
Esophagus: When material is swallowed, a coordinated and sequential set of peristaltic contractions produces a zone of pressure that moves down the esophagus with the bolus in front of it. The time required for the wave to travel from the pharynx to the stomach typically is 4–12 sec. The esophagus may not be totally emptied by the original peristaltic contraction initiated by the swallow. Several secondary contractions often are required to remove the remaining material, and some material can remain for several minutes or even hours in the esophagus. In the HATM, esophageal transit is represented by two components: a fast component representing movement in front of the initial peristaltic contraction initiated by the swallow, and a slow component representing transfer of residual swallowed material. Reported mean transit times for the fast component are summarized in Figure 6.10 . Baseline transit times used in the HATM for the fast and slow components of transfer of material through the esophagus are listed in Table 6.5 .
Nanoemulsions: A New Application in Nutraceutical and Food Industry
Published in Bhupinder Singh, Minna Hakkarainen, Kamalinder K. Singh, NanoNutraceuticals, 2019
Silki Chandel, Priyanka Jain, Saket Asati, Vandana Soni
Small Intestine: Partially digested bolus comes into contact with the higher pH medium of the small intestine, where it is mixed with the alkaline digestive enzymes. The digestion of surfactant in the nanoemulsion is affected by the surface active substances present in the small intestine. Various digestive enzymes (such as pancreatic lipase/co-lipase complex) may hydrolyze the components present within nanoemulsion droplet. These enzymes facilitate the conversion of diglycerides and triglycerides into free fatty acids and monoglycerides. In another case, proteins and phospholipids are digested by protease and phospholipase enzymes to peptides, amino acids, and to free fatty acids, respectively. Lipophilic or lipid components, like pharmaceuticals or nutraceuticals, encapsulated into the mixed micelles and vesicles, will also be moved into the enterocytes from the mucous layer, where they are absorbed. The behavior and properties of the nanoemulsions will be changed due to its exposure at various physiological conditions (McClements et al., 2007b). The possible changes may be in the form of either changes in the composition of oil, water or surfactant or in aggregation state, size distribution, charges, interfacial characteristics, and physical state of the nanoemulsions. All these alterations are considered as the major factor for understanding the potential toxicity and fate of nanoemulsion formulation in the human body (Chen et al., 2017).
Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2016
David J. Baker, Naima Bradley, Alec Dobney, Virginia Murray, Jill R. Meara, John O’Hagan, Neil P. McColl, Caryn L. Cox
The food formed into a bolus in the mouth passes down the oesophagus due to propulsive contractions of the muscle of the oesophagus, which are controlled by another parasympathetic cranial nerve, the vagus. Then the food enters the stomach which not only acts as a storage organ but also promotes digestion by secretions (pepsin and hydrochloric acid for digestion of proteins) from the cells lining the stomach wall. The secretions of the stomach are also under control of the vagus nerve and also a hormone called gastrin.
Extracting moving boundaries from dynamic, multislice CT images for fluid simulation
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Andrew Kenneth Ho, Yoko Inamoto, Eiichi Saitoh, Sheldon Green, Sidney Fels
The anatomical regions of the airway included were the oral cavity, pharynx, larynx, trachea, oesophagus and nasopharynx. In normal swallowing, the bolus travels from the oral cavity, through the pharynx, and into the oesophagus. By including the nasopharynx, larynx and trachea, we can check that the simulation obtains adequate closure of the vocal folds and nasopharyngeal passage in order to prevent aspiration (see Figure 2(b)).