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Macromolecular Absorption From The Digestive Tract In Young Vertebrates
Published in Károly Baintner, Intestinal Absorption of Macromolecules and Immune Transmission from Mother to Young, 2019
The proximal small intestine of the rat secretes H+ ions124 and provides a slightly acidic medium (pH 6.2 to 6.3) for the binding of IgG.1212 In the intermicrovillus spaces similar pH may prevail as in the bulk of chyme. The distal small intestine lacks receptors (see Section A above), and its pH approaches neutrality, which makes it unfavorable for binding.1212
The digestive system
Published in Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella, Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella
The large intestine typically receives 500–1500 mL of chyme from the small intestine per day. As discussed, most digestion and absorption has already taken place in the small intestine. In fact, there are no digestive enzymes produced by the large intestine. At this point in the human digestive tract, the chyme consists of indigestible food residues (e.g., cellulose), unabsorbed biliary components, and any remaining fluid. Therefore, the two major functions of the large intestine are: DryingStorage
The stomach and gastric function
Published in Paul Ong, Rachel Skittrall, Gastrointestinal Nursing, 2017
The presence of certain nutrients in the small intestines triggers the release of hormones from enteroendocrine cells directly into the lamina propria which are then absorbed into the blood circulation and further contribute to suppression of gastric activity. Lipids and carbohydrates stimulate the release of cholecystokinin (CCK) and gastric inhibitory peptide (GIP). CCK and GIP inhibit the release of acids and enzymes and GIP also slows down gastric motility. As chyme enters the duodenum it will bring with it acid which will lower the pH in the duodenum. This stimulates enteroendocrine cells to release secretin which has the effect of inhibiting the release of acid from the parietal cells and pepsinogen from the chief cells. Secretin also triggers the release of a bicarbonate-rich secretion from epithelial duct cells lining pancreatic and biliary ducts. This bicarbonate-rich secretion has a pH of 7.5–8.8 which travels along the pancreatic and biliary ducts and enters into the duodenum via the hepatopancreatic ampulla. It serves to dilute and buffer the acids within the chyme that enter into the duodenum. This provides the right pH for enzyme activity in the small intestine.
High internal phase Pickering emulsions stabilised by ultrasound-induced soy protein-β-glucan-catechin complex nanoparticles to enhance the stability and bioaccessibility of curcumin
Published in Journal of Microencapsulation, 2023
Xutao Chen, Junrong Huang, Linlin Chen, Xiaona Chen, Danxia Su, Bei Jin
An in vitro gastrointestinal model was used to evaluate the performance of HIPPEs as a nutraceutical delivery vehicle based on a previous study (Zhang et al.2022d) with some modifications. Briefly, 20 ml Curcumin-loaded HIPPEs samples were mixed with an equal volume of SSF (containing 0.298 g/L NaCl, 0.896 g/L KCl, 0.2 g/L KSCN, 1.694 g/L NaHCO3, 0.888 g/L NaH2PO4, 0.57 g/L Na2SO4, 0.6 g/L amylase, 0.2 g/L urea, and 0.015 g/L uric acid). The pH was adjusted to 6.8 using 1.0 mol/l HCl or 1.0 mol/l NaOH. The mixed solution was incubated at 37 °C for 5 min in a constant-temperature incubator. Subsequently, 20 ml of oral digestion mixtures were transferred into 100 ml simulated gastric fluid (SGF), which contained 3.2 mg/mL of pepsin and 2.0 mg/mL of NaCl. Then the mixture was incubated in a shaking water bath at 37 °C for 120 min after adjusting the pH to 2.0. After the simulated gastric digestion, 30 ml chyme samples were mixed with 30 ml of SIF (containing 8 mg/mL of bile salt, 1.11 g/L CaCl2, 7.01 g/L NaCl, and 1 mg/mL of pancreatin, pH 6.8). The mixture was shaken at 37 °C for 4 h. Average droplet size (d4,3) and microscopic observation for HIPPEs before and after the oral, gastric, and intestinal phases were performed.
Impact of in vitro digestion on gastrointestinal fate and uptake of silver nanoparticles with different surface modifications
Published in Nanotoxicology, 2020
Ashraf Abdelkhaliq, Meike van der Zande, Anna K. Undas, Ruud J. B. Peters, Hans Bouwmeester
A volume of 1 mL, with a concentration of 500 mg/L of AgNPs suspensions or 95 mg/L AgNO3 solution, was mixed with 3 mL of saliva (pH 6.8 ± 0.1) and incubated (head-over-heals at 55 rpm) for 5 min at 37 °C to simulate the digestion in the mouth. Subsequently, 6 mL of gastric juice (pH 1.3 ± 0.1) was added to the mixture and the pH was checked and adjusted to 5 ± 0.5 with NaOH (5 M) to simulate the digestion in the stomach. The samples were further incubated while rotating at head-over-heals at 37 °C for 2 h. Lastly, 6 mL of duodenal juice (pH 8.1) and 3 mL of bile (pH 8.2) were added to the mixture and the pH was checked and adjusted to 6.5 ± 0.5 with NaOH (1 M) or HCl (37%) to simulate the digestion in the small intestine. Again, the samples were incubated while rotating head-over-heals at 37 °C for 2 h. The complete mixture of all the digestive juices is further referred to as chyme.
Targeting the intestinal lymphatic system: a versatile path for enhanced oral bioavailability of drugs
Published in Expert Opinion on Drug Delivery, 2018
Renuka Suresh Managuli, Sushil Yadaorao Raut, Meka Sreenivasa Reddy, Srinivas Mutalik
Small intestine consists of four tissue layer: i) innermost mucosa layer which is involved in nutrients absorption from partly digested food (chyme); ii) middle submucosa layer consists of nerves, blood, and lymphatic vessels which transport nutrients from intestine to rest of the body; iii) down to submucosa layer exists the muscularis layer consisting of several layers of smooth muscle tissues which aids in contraction of small intestine, and iv) outermost is the serosa layer which along with the mesentery surrounds the intestine. The interior wall of the small intestine is in the form of circular folds and the epithelial lining of the mucosal layer is protruded into finger like projections known as villi (singular: villus). Around 20,000 villi are present per square inch of mucosa [13]. The epithelial cells in the small intestine comprising enterocytes (absorptive cells), goblet cells, paneth cells, enteroendocrine cells, and tuft cells are held together by tight junctions forming a barrier and they possess a brush border surface onto them known as microvilli [14]. The circular folds and projections (villi and microvilli) increase the intestinal surface area thereby offering maximum contact between epithelial cells and chyme for optimum absorption of nutrients.