Food Digestion
Janis Baines, David Borradale, Janeane Dart, Leisa McCarthy, Christina McKerchar, Claire Palermo, Gayle S. Savige, Jolieke C. van der Pols, Naiyana Wattanapenpaiboon in Food and Nutrition, 2020
This chapter describes the roles of the specialised areas of the gastrointestinal tract, together with associated specialised organs, in digestion. The digestive system is the pathway through which food is taken into the body and converted to base substances to ensure the body’s ongoing optimal functioning before eliminating anything not required. Digestion begins before food enters the system. The ‘cephalic phase’ is the phase of gastric secretion before food enters the stomach. Food enters the mouth and mechanical digestion of the food, especially hard foods, starts with the action of chewing. Mixing food with digestive secretions in the stomach effectively liquefies it to the consistency of a gruel or thick soup, and this is aided by peristaltic waves of muscle contraction. The interval between eating food materials and the time when the food residues are discharged from the body as faeces varies widely depending on individual characteristics and the diet consumed, and may vary day to day.
Disorders and drugs of the digestive system
Roger McFadden in Introducing Pharmacology, 2019
This chapter explores some problems such as indigestion, constipation and diarrhoea are referred to as disorders rather than pathologies. Some disorders, of course, can develop into something more serious, truly deserving of the term pathology. The chapter examines the digestive system in relation to the common disorders that can affect most of us–indigestion and constipation. The principal task of the digestive system is to transfer the nutrients from the food we eat into our body, where those nutrients will be used for processes such as energy, protein production and general tissue maintenance. Any diseases or drugs that inhibit the production of saliva can result in recurrent mouth infections. There are various accessory organs associated with the digestive system such as the pancreas that secretes digestive enzymes into the duodenum to assist with the breakdown of food into its component parts. The digestive system contributes to homeostasis by maintaining the supply of essential nutrients to the body.
Disorders of the digestive tract
Judy Bothamley, Maureen Boyle in Medical Conditions Affecting Pregnancy and Childbirth, 2020
The digestive system’s main function is to transfer nutrients, water and electrolytes from food to fuel cellular activity and provide the building blocks for renewal and development of body tissue. In pregnancy pressure from the enlarging uterus and changes mediated by oestrogen and progesterone cause anatomical and physiological adjustments that support enhanced demands for maternal and fetal nutrition. Many 158 of the so-called minor disorders of pregnancy are attributed to changes to the digestive system, including nausea and vomiting of early pregnancy, constipation, food cravings and heartburn. Delay in the diagnosis of more serious conditions of the digestive tract may occur and, where problems exist, fetal requirements may be compromised.
Small intestinal microbiota: the neglected stepchild needed for fat digestion and absorption
Published in Gut Microbes, 2019
Eugene B. Chang, Kristina Martinez-Guryn
Our recently published paper “Small Intestine Microbiota Regulate Digestive and Absorptive Adaptive Responses to Dietary Lipids” in Cell Host & Microbe explored the neglected small intestine microbiota and demonstrated its critical role as a regulator of fat digestion and absorption. This work generated the following important take home messages: 1) small intestinal microbes are particularly sensitive to high fat diets and turn on host processes regulating fat digestion and transport, 2) this action is very likely orchestrated by a consortium of microbes, each having different specific effects and targets, and 3) the actions of this consortium appear to be mediated by bacteria-derived small molecules or bioactive components. These findings are expected to provide insight into developing treatments for conditions of under- or over-nutrition. The goal of this addendum is to summarize our findings, address issues related to gut microbiota and gnotobiotic research specifically regarding technology and experimental design, discuss this work in the context of relevant literature, and lastly provide considerations for future research.
Endoplasmic reticulum stress and the pancreatic acinar cell
Published in Expert Review of Gastroenterology & Hepatology, 2008
Constanze H Kubisch, Craig D Logsdon
The pancreas is the primary organ responsible for the digestion of food. Pancreatic acinar cells are specialized for the production of digestive enzymes, and these cells have a higher rate of protein synthesis than all other adult human tissues. Digestive enzymes are produced in the endoplasmic reticulum (ER), a multifunctional organelle responsible for the synthesis and correct folding of proteins in the secretory pathway. Disturbances of ER function lead to stress-response mechanisms that can restore homeostasis but can also, if uncontrolled, cause disease. Pancreatic acinar cells are particularly susceptible to ER perturbations, and mechanisms that relieve ER stress are necessary for normal pancreatic development. Furthermore, ER stress occurs during acute pancreatitis, and may also be present in pancreatic cancer. However, the specific roles of ER stress-response mechanisms in these diseases are unknown.
Biological artificial fluid-induced non-lamellar phases in glyceryl monooleate: the kinetics pathway and its digestive process by bile salts
Published in Drug Development and Industrial Pharmacy, 2014
Yanyan Zhou, Qifang Wang, Yan Wang, Hui Xu, Bo Yuan, Sanming Li, Hongzhuo Liu
Background: The cubic (QII) phase is a promising sustained-release system. However, its rigid gel-like propensity is highly viscous, which makes it difficult to handle in pharmaceutical applications. To circumvent this problem, a less viscous lamellar (Lα) phase that could spontaneously transform to QII phase by the introduction of water or biological artificial fluid can be used. However, the kinetics pathway of phase transition, susceptibility to digestive processes and impact of the transition on drug release are not yet well understood. Method: We investigated various biological artificial fluid-induced Lα to inverse QII phase transition over time in glyceryl monooleate (GMO) by water penetration scan and light polarizing microscopy. To reveal the structure stability, fluorescence spectroscopy studies were conducted using pyrene as a probe. Furthermore, the release mechanism of pyrene as a lipophilic drug model in the spontaneously formed QII was investigated. Result: Although hexagonal (HII) mesophases occurred when phosphate buffered saline (PBS) 7.4, 0.1 M HCl or sodium taurocholate (NaTC) solutions were introduced to GMO at room temperature, they disappear with the exception of 0.1 M HCl at 37 °C. Compared with 25 °C, Lα to QII phase transition was in a faster rate as almost completely transforms were observed after 2 h post-immersion. The spontaneously formed mesophases were stable over 24 h immersions in PBS or pancreatic lipase solutions as proven by the extremely low fluorescence signal, however they were digestible by bile salts. This result indicated that digestion by bile salts was the major pathway instead of digestion by lipases. Moreover, pyrene fluorescence spectroscopy confirmed that the digestion by bile salts induced the formation of GMO–bile salt mixed micelles whose performance depended on the bile salt concentrations. This dependence influenced the drug release from the spontaneously formed QII phase. Conclusion: All the results concluded that temperature, pH and ionic strength tendencies for the formation of non-lamellar structures greatly influenced the self-assembly process, thereby affecting the final mesophase structure. The results of this study are important to understand the lamellar to non-lamellar lipid-phase transitions and their possible pharmaceutical applications.
Related Knowledge Centers
- Digestive System
- Food
- Small Intestine
- Salivary Glands
- Nutritional Physiological Phenomena
- Ruminants
- Digestive System Physiological Phenomena