Introduction
Paul Ong, Rachel Skittrall in Gastrointestinal Nursing, 2017
There are a number of complex processes that take place within the gastrointestinal tract and associated accessory organs; however, most of the sections of the gastrointestinal tract will share three fundamental processes: secretion, absorption and motility. The level of specialism in each of these three areas will be dependent upon the function to be carried out: Secretion – mucous from goblet cells to aid protection and lubrication; enzymes from the glandular cells of the salivary glands and pancreas as well as the epithelial cells of the stomach and small intestine; hormones from the enteroendocrine cells which line the stomach and duodenum; bile from the gallbladder to aid in the digestion of fats.Absorption – water, electrolytes, monosaccharides (e.g. glucose), amino acids and fats from the lumen of the small intestine cross the plasma membrane into enterocytes via the processes of diffusion, co-transport and osmosis and then move into the blood circulation by diffusion.Motility – the movement of smooth muscle contractions during peristalsis and segmentation in the wall of the gastrointestinal tract mix and propel food material.
Prolactin and the Regulation if Secretion Including Membrane Flow: Potential Roles for Tubulin and Microtubules*
James A. Rillema in Actions of Prolactin on Molecular Processes, 1987
Few cellular processes integrate structure and function in the number and variety of ways as does secretion. Advances in almost any area of cell biology such as receptor physiology, membrane excitability, peptide synthesis, fluid and electrolyte transport, membrane-bound enzyme complexes, cell ultrastructure, energy metabolism, gene expression, motility and contractility, protein phosphorylation, calcium and cyclic nucleotide second messengers, etc. have found some application in the secretory process, thus accounting for rapid advances in our understanding. The Latin root for secretion means “to separate” and reflects the original concept of a process in which glands simply filter substances from the blood. We now know that most types of secretions are a mix of epithelial cell products synthesized de novo, and plasma substances transported across the epithelial sheet either transcellularly or between the cells, paracellularly. In exocrine cells, contributions may occur in gland regions where secretory cells are clustered into designated secretory sites (acini or alveoli) or along ducts.
Importance of the Microcirculation to Intestinal Secretion
T. S. Gaginella in Regulatory Mechanisms — in — Gastrointestinal Function, 2017
Secretion is a normal function of the gastrointestinal tract, supplying H20, solutes, and enzymes for digesting and dissolving ingested nutrients, bringing chyme to isotonic concentrations, and, perhaps, lubricating the passage of chyme down the intestine.12 Secretion may be pathologic, e.g., due to bacterial toxins, and may result in sufficient loss of plasma volume to cause cardiovascular collapse. Secretion may be relative, representing decreased absorption, or absolute, representing net entry into the lumen. Secretions can be nonspecific and composed of a solution that is primarily an ultrafiltrate of plasma or can be relatively enriched in a specific component such as bicarbonate or chloride. Secretion may occur due to vascular effects and/or specific neural, paracrine, or hormonal stimuli. These regulatory signals can act on cell secretory mechanisms and/or the microcirculation. This chapter discusses some normal and pathologic influences on the secretion of salt and water by the intestine.
Synergistic effect of ursolic acid and piperine in CCl4 induced hepatotoxicity
Published in Annals of Medicine, 2021
Sayan Biswas, Amit Kar, Nanaocha Sharma, Pallab K. Haldar, Pulok K. Mukherjee
The liver is a major body organ performing a variety of physiological and biochemical processes. Its main functions include metabolism, storage, and secretion. It is involved in detoxifying the body from endogenous waste metabolites as well as exogenous xenobiotics. The liver metabolizes carbohydrates and fats, secretes bile and stores certain vitamins. Therefore, diseases affecting normal liver functioning are a major threat to public health. Hepatic or liver disease is a collective term and encompasses cell, tissue or structural damage of liver due to microorganisms such as bacteria, virus, parasites, autoimmune disorders including immune hepatitis, primary biliary cirrhosis, etc excess drug toxicity involving drugs such as paracetamol, certain antitubercular drugs, etc), hepatotoxic compounds such as carbon tetrachloride (CCl4), thioacetamide, D-galactosamine/lipopolysaccharide, etc) and alcohol. Out of these compounds, Carbon tetrachloride (CCl4) has been extensively used to induce liver damage in animal models due to its similarity with hepatic injury in humans [7]. Carbon tetrachloride (CCl4) exerts its hepatotoxic action due to the formation of trichloromethyl-free radicals (–CCl3 or CCl3OO–) by cytochrome P450 enzymes (CYP 450) present in the liver. These free radicals induce lipid peroxidation in liver cells thus decreasing the antioxidant enzymes used to counter this oxidative damage. This causes damage to hepatic parenchyma cells leading to hepatotoxicity [8].
The Effects of Perioperative Probiotics on Postoperative Gastrointestinal Function in Patients with Brain Tumors: A Randomized, Placebo-Controlled Study
Published in Nutrition and Cancer, 2023
Mengyang Jiang, Xiaoyu Zhang, Yiqiang Zhang, Yang Liu, Ran Geng, Haixia Liu, Yongxing Sun, Baoguo Wang
The primary functions of the gastrointestinal tract are motility, secretion, absorption, and serving as a barrier. Nervous system disorders affecting gastrointestinal function are characterized primarily by abnormalities in motility rather than secretion (6). Gastrointestinal motility is regulated at multiple levels, including the central and enteric nervous systems as well as the microbiome (26,27). Surgery-induced stress and inflammatory responses activate the sympathetic and enteric nervous systems, leading to gastrointestinal dysfunction and thus disturbing motility and transit (28). This process involves the immune system, inflammatory cells, reactive enteric glia, neurons, smooth muscle cells, epithelial cells, and the microbiome in the intestinal lumen (8). Postoperative gastrointestinal dysfunction can not only cause short-term complications, but may also lead to long-term complications after inflammation subsides (29). The incidence of postoperative gastrointestinal dysfunction in adults with neurological diseases is more than twice that for individuals with non-neurological diseases (2).
Growth rate alterations of human colorectal cancer cells by 157 gut bacteria
Published in Gut Microbes, 2020
Rahwa Taddese, Daniel R. Garza, Lilian N. Ruiter, Marien I. de Jonge, Clara Belzer, Steven Aalvink, Iris D. Nagtegaal, Bas E. Dutilh, Annemarie Boleij
Several functional categories were significantly associated with cell growth. Most of these functions were identified in specific bacterial families and consistently inhibited or enhanced cell growth in different cell lines. These functions may reflect novel pathways of bacterial interference with cell growth which, to our knowledge, have not been previously identified. Most functions are related to cell metabolism, secretion, and transport systems. For example, secretomes of Enterobacteriaceae that encode the “Vir-like type 4 secretion system” inhibited the growth of all cell lines. Similarly, the gene superclass “Membrane transport” was mostly associated with secretomes that inhibited cell growth (Supplementary Table S10). Molecules that are secreted by these bacterial transport systems may be responsible for the inhibiting effect. For example, the Vir-like type 4 secretion system allows bacteria to secrete proteinaceous effectors that kill competitors.90 Here, we report an important first step in understanding the cell growth enhancing or inhibiting effects of human gut bacteria by identifying putative transport systems for effector molecules.
Related Knowledge Centers
- Enzyme
- Excretion
- Protein
- Toxin
- Cell Membrane
- Lipoprotein
- Cell
- Gland
- Porosome
- Bacterial Secretion System