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Vasoactive Intestinal Peptide
Vasoactive intestinal peptide, also known as vasoactive intestinal polypeptide or VIP, is a peptide hormone that is vasoactive in the intestine. VIP is a peptide of 28 amino acid residues that belongs to a glucagon/secretin superfamily, the ligand of class II G protein–coupled receptors. VIP is produced in many tissues of vertebrates including the gut, pancreas, and suprachiasmatic nuclei of the hypothalamus in the brain. VIP stimulates contractility in the heart, causes vasodilation, increases glycogenolysis, lowers arterial blood pressure and relaxes the smooth muscle of trachea, stomach and gallbladder. In humans, the vasoactive intestinal peptide is encoded by the ''VIP'' gene. VIP has a half-life (t½) in the blood of about two minutes. Function In the body VIP has an effect on several tissues: In the digestive system, VIP seems to induce smooth muscle relaxation ( lower esophageal sphincter, stomach, gallbladder), stimulate secretion of water into pancreat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peptide Hormone
Peptide hormones or protein hormones are hormones whose molecules are peptide, or proteins, respectively. The latter have longer amino acid chain lengths than the former. These hormones have an effect on the endocrine system of animals, including humans. Most hormones can be classified as either amino acid–based hormones (amine, peptide, or protein) or steroid hormones. The former are water-soluble and act on the surface of target cells via second messengers; the latter, being lipid-soluble, move through the plasma membranes of target cells (both cytoplasmic and nuclear) to act within their nuclei. Like all peptides and proteins, peptide hormones and protein hormones are synthesized in cells from amino acids according to mRNA transcripts, which are synthesized from DNA templates inside the cell nucleus. Preprohormones, peptide hormone precursors, are then processed in several stages, typically in the endoplasmic reticulum, including removal of the N-terminal signal sequence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate Trachea
The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the larynx and branches into the two primary bronchi. At the top of the trachea the cricoid cartilage attaches it to the larynx. The trachea is formed by a number of horseshoe-shaped rings, joined together vertically by overlying ligaments, and by the trachealis muscle at their ends. The epiglottis closes the opening to the larynx during swallowing. The trachea begins to form in the second month of embryo development, becoming longer and more fixed in its position over time. It is epithelium lined with column-shaped cells that have hair-like extensions called cilia, with scattered goblet cells that produce protective mucins. The trachea can be affected by inflammation or infection, usually as a result of a viral illness affecting other part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastric Chief Cell
A gastric chief cell (or peptic cell, or gastric zymogenic cell) is a type of gastric gland cell that releases pepsinogen and gastric lipase. It is the cell responsible for secretion of chymosin in ruminant animals. The cell stains basophilic upon H&E staining due to the large proportion of rough endoplasmic reticulum in its cytoplasm. Gastric chief cells are generally located deep in the mucosal layer of the stomach lining, in the fundus and body of the stomach.pathologyoutlines.com/topic/stomachnormalhistology.html Chief cells release the zymogen (enzyme precursor) pepsinogen when stimulated by a variety of factors including cholinergic activity from the vagus nerve and acidic condition in the stomach. Gastrin and secretin may also act as secretagogues. It works in conjunction with the parietal cell, which releases gastric acid, converting the pepsinogen into pepsin. Nomenclature The terms ''chief cell'' and '' zymogenic cell'' are often used without the word "gastric" to name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pepsinogen
Pepsin is an endopeptidase that breaks down proteins into smaller peptides. It is produced in the gastric chief cells of the stomach lining and is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pepsin is an aspartic protease, using a catalytic aspartate in its active site. It is one of three principal endopeptidases (enzymes cutting proteins in the middle) in the human digestive system, the other two being chymotrypsin and trypsin. There are also exopeptidases which remove individual amino acids at both ends of proteins (carboxypeptidases produced by the pancreas and aminopeptidases secreted by the small intestine). During the process of digestion, these enzymes, each of which is specialized in severing links between particular types of amino acids, collaborate to break down dietary proteins into their components, i.e., peptides and amino acids, which can be readily absorbed by the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastrin
Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin binds to cholecystokinin B receptors to stimulate the release of histamines in enterochromaffin-like cells, and it induces the insertion of K+/H+ ATPase pumps into the apical membrane of parietal cells (which in turn increases H+ release into the stomach cavity). Its release is stimulated by peptides in the lumen of the stomach. Physiology Genetics In humans, the ''GAS'' gene is located on the long arm of the seventeenth chromosome (17q21). Synthesis Gastrin is a linear peptide hormone produced by G cells of the duodenum and in the pyloric antrum of the stomach. It is secreted into the bloodstream. The encoded polypeptide is preprogastrin, which is cleaved by enzymes in posttranslational modification to produce progastrin (an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPnotebook
GPnotebook is a British medical database for general practitioners (GPs). It is an online encyclopaedia of medicine that provides an immediate reference resource for clinician A clinician is a health care professional typically employed at a skilled nursing facility or clinic. Clinicians work directly with patients rather than in a laboratory or as a researcher. A clinician may diagnose, treat, and otherwise care for pat ...s worldwide. The database consists of over 30,000 index terms and over two million words of information. GPnotebook is provided online by Oxbridge Solutions Limited GPnotebook website is primarily designed with the needs of general practitioners (GPs) in mind, and written by a variety of specialists, ranging from paediatrics to accident and emergency. The original idea for the database began in the canteen of John Radcliffe Hospital in 1990 while James McMorran, a first year Oxford University clinical student, was writing up his medical notes. Instead of wr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrolytes
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dissolving, the substance separates into cations and anions, which disperse uniformly throughout the solvent. Solid-state electrolytes also exist. In medicine and sometimes in chemistry, the term electrolyte refers to the substance that is dissolved. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. Some gases, such as hydrogen chloride (HCl), under conditions of high temperature or low pressure can also function as electrolytes. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastric Acid
Gastric acid, gastric juice, or stomach acid is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the long chains of amino acids of proteins. Gastric acid is regulated in feedback systems to increase production when needed, such as after a meal. Other cells in the stomach produce bicarbonate, a base, to buffer the fluid, ensuring a regulated pH. These cells also produce mucus – a viscous barrier to prevent gastric acid from damaging the stomach. The pancreas further produces large amounts of bicarbonate and secretes bicarbonate through the pancreatic duct to the duodenum to neutralize gastric acid passing into the digestive tract. The active components of gastric acid are protons and chloride. Often simplistically described as hydrochloric acid, these species are produced by parietal cells in the gastric glands in the stomach. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bile
Bile (from Latin ''bilis''), or gall, is a dark-green-to-yellowish-brown fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is produced continuously by the liver (liver bile) and stored and concentrated in the gallbladder. After eating, this stored bile is discharged into the duodenum. The composition of hepatic bile is (97–98)% water, 0.7% bile salts, 0.2% bilirubin, 0.51% fats (cholesterol, fatty acids, and lecithin), and 200 meq/L inorganic salts. The two main pigments of bile are bilirubin, which is yellow, and its oxidised form biliverdin, which is green. When mixed, they are responsible for the brown color of feces. About 400 to 800 millilitres of bile is produced per day in adult human beings. Function Bile or gall acts to some extent as a surfactant, helping to emulsify the lipids in food. Bile salt anions are hydrophilic on one side and hydrophobic on the other side; consequently, they tend t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pancreatic Juice
Pancreatic juice is a liquid secreted by the pancreas, which contains a number of digestive enzymes, including trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase, nucleases and amylase. The pancreas is located in the visceral region, and is a major part of the digestive system required for proper digestion and subsequent assimilation of macronutrient substances required for living. Pancreatic juice is alkaline in nature due to the high concentration of bicarbonate ions. Bicarbonate is useful in neutralizing the acidic gastric acid, allowing for effective enzymic changes. Pancreatic juice secretion is principally regulated by the hormones secretin and cholecystokinin, which are produced by the walls of the duodenum, and by the action of autonomic innervation. The release of these hormones into the blood is stimulated by the entry of the acidic chyme into the duodenum. Their coordinated action results in the secretion of a large volume of pancreatic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Esophageal Sphincter
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach. The esophagus is a fibromuscular tube, about long in adults, that travels behind the trachea and heart, passes through the diaphragm, and empties into the uppermost region of the stomach. During swallowing, the epiglottis tilts backwards to prevent food from going down the larynx and lungs. The word ''oesophagus'' is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, “I carry”) + ἔφαγον (éphagon, “I ate”). The wall of the esophagus from the lumen outwards consists of mucosa, submucosa (connective tissue), layers of muscle fibers between layers of fibrous tissue, and an outer layer of connective tissue. The mucosa is a stratified squamous epithelium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digestive System
The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages: the cephalic phase, the Regulation of gastric function#Gastric phase, gastric phase, and the Regulation of gastric function#Intestinal phase, intestinal phase. The first stage, the cephalic phase of digestion, begins with secretions from gastric glands in response to the sight and smell of food. This stage includes the mechanical breakdown of food by chewing, and the chemical breakdown by digestive enzymes, that takes place in the human mouth, mouth. Saliva contains the digestive enzymes amylase, and lingual lipase, secreted by the salivary gland, salivary and serous glands on the tongue. Chewing, in which the food is mixed with saliva ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
