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Organoid Technology for Basic Science and Biomedical Research
Published in Hyun Jung Kim, Biomimetic Microengineering, 2020
Szu-Hsien (Sam) Wu, Jihoon Kim, Bon-Kyoung Koo
The stomach contains two main anatomical parts: the corpus and antrum in humans, and the forestomach (rostral), corpus, and antrum (caudal) in mice. Unlike the protruding villus structures in the small intestine, the stomach contains invaginated glands in the corpus and antral parts. The gastric glands are divided into four anatomical segments (from top to bottom of the gland): the gastric pit, isthmus, neck, and base regions (Kim and Shivdasani 2016). Each part of the stomach gland contains different cell types which carry out specific functions, such as mucus-secreting pit cells, rapidly dividing cells in the isthmus region, mucus-secreting neck cells and terminally differentiated enzyme-secreting chief cells. In between these cells, hormone-secreting enteroendocrine cells are also found throughout the gland and parietal cells, which secrete hydrochloric acid, are abundant within the corpus glands.
Gastrointestinal System
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
e stomach is somewhat pyriform in shape with its large end directed upward at the lower esophageal sphincter and its small end bent to the right at the pylorus. It has two curvatures, the greater curvature which is four to ve times as long as the lesser curvature, and it consists of three regions, namely, the fundus, the corpus (or body), and the antrum, respectively. It has three smooth muscle layers. e outermost layer is the longitudinal muscle layer, the middle is the circular muscle layer, and the innermost is the oblique muscle layer. ese layers thicken gradually in the distal stomach toward the pylorus, which is consistent with stomach function since trituration occurs in the distal antrum. e size of the stomach varies considerably Famong subjects. In an adult male, its greatest length when distended is about 25-30 cm and its widest diameter is about 10-12 cm (Pick and Howden, 1977).
Biological Fate of Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
S. Parthasarathi, C. Anandharamakrishnan
The oral route of administration is considered to be the most common and accessible way of administrating nutraceutical formulations. The food digestion process is carried out in the gastrointestinal tract and it is composed of several sections which differ in their chemical and enzymatic compositions and pH (Figure 12.5). Mastication or chewing is the first step in food digestion, which reduces particle size and creates the food bolus. The oral cavity (mouth) is followed by the pharynx and esophagus, and the food bolus is conveyed to the stomach by a peristalsis process. The stomach is divided into four major regions: fundus, body, antrum, and pylorus, and it has three main motor functions: storage, mixing, and emptying. The proximal part of the stomach is fundus and body, which act as a reservoir for undigested food materials (Kong and Singh, 2008). The proximal part initiates contact between bolus and gastric juice. Gastric juice is mainly composed of enzymes, pepsin, and lipase, hydrochloric acid leading to a regular fall in pH (approximately from pH 6–5 to 1.5), promoting digestion. The distal part of the stomach is antrum and pylorus, responsible for grinding, mixing, and sieving solid food materials, and acts as a pump for gastric emptying by propelling actions. Gastric emptying conveys the food bolus into the small intestine, where absorption of nutrients takes place at more neutral or slightly basic pH values (Malhaire et al., 2016).
Systematic review on gastric electrical stimulation in obesity treatment
Published in Expert Review of Medical Devices, 2019
Alimujiang Maisiyiti, Jiande Dz Chen
Upon food ingestion, the proximal stomach relaxes to accommodate the ingested food, a physiological process called gastric accommodation. Gastric accommodation is controlled by a vago-vagal reflex triggered by meal ingestion and mediated by the activation of inhibitory nitrergic motor neurons in the gastric wall which produce fundic relaxation. Gastric accommodation to a meal consists of relaxation of the proximal stomach, providing the meal with a reservoir and enabling a volume increase without a rise in gastric pressure [11]. Whereas, the function of the distal stomach, the antrum, is to generate peristalsis to push the ingested food through the pylorus to the duodenum, a process called gastric emptying. Gastric emptying is determined by the propulsive antral contractions and the appreciate opening of the pylorus. The frequency and coordination of the antral contractions are determined by the gastric pace-making activity [12] that is also called the slow wave due to its slow rhythm (3 cycles/min). Disruption of this pace-making activity impairs antral contractions and leads to delayed gastric emptying [12].
Localization strategies for robotic endoscopic capsules: a review
Published in Expert Review of Medical Devices, 2019
Federico Bianchi, Antonino Masaracchia, Erfan Shojaei Barjuei, Arianna Menciassi, Alberto Arezzo, Anastasios Koulaouzidis, Danail Stoyanov, Paolo Dario, Gastone Ciuti
MRI technology has been also employed in designing a novel magnetic technology to steer a capsule during a gastric examination. In that case, as for the computer-vision based technology, capsule localization is performed with respect to the surrounding deformable anatomical environment and targets (i.e. internal localization), for example, landmarks and 3D geometry. That system [94,95], developed cooperatively by Olympus Inc. and Siemens Healthcare (Erlangen, Germany), includes an Olympus Inc. capsule endoscope (31 mm in length and 11 mm in diameter, provided with two 4 frames/s image sensors) and Siemens magnetic guidance equipment, composed of magnetic resonance imaging and computer tomography (CT). Two joysticks were used by physicians in order to perform a five DoFs steering control of the capsule, that is, 3D translation and tilting and rotation, inside the stomach. This framework, validated over a set of 55 volunteers and consentient patients, shows a promising recognition of the gastric pylorus, antrum, body, fundus, and cardia in 96%, 98%, 96%, 73%, and 75% of participants, respectively.
Intraobserver and interobserver reliability of visible light spectroscopy during upper gastrointestinal endoscopy
Published in Expert Review of Medical Devices, 2018
Louisa J.D. van Dijk, Twan van der Wel, Desirée van Noord, Adriaan Moelker, Hence J.M. Verhagen, Daan Nieboer, Ernst J. Kuipers, Marco J. Bruno
VLS measurements are noninvasive and performed during upper endoscopy using a fiber-optic probe passed through the accessory channel of the endoscope. This probe emits white light and detects differences in the absorption spectra of the oxygenated and deoxygenated hemoglobin molecules [6]. The measured mucosal saturation reflects indirectly the adequacy of the gastrointestinal blood flow. VLS measurements are performed in clinical practice at three different locations during upper endoscopy: the antrum of the stomach, the duodenal bulb, and the descending duodenum. Based on previously determined cutoff values [4] in CMI-suspected patients, the outcomes are defined positive for ischemia if the measured saturation value is lower than 63% in the antrum, 62% in the duodenal bulb, and 58% in the descending duodenum in fasting state.