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Myenteric Plexus
The myenteric plexus (or Auerbach's plexus) provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input (although present ganglion cell bodies belong to parasympathetic innervation, fibers from sympathetic innervation also reach the plexus), whereas the submucous plexus provides secretomotor innervation to the mucosa nearest the lumen of the gut. It arises from cells in the vagal trigone also known as the nucleus ala cinerea, the parasympathetic nucleus of origin for the tenth cranial nerve (vagus nerve), located in the medulla oblongata. The fibers are carried by both the anterior and posterior vagal nerves. The myenteric plexus is the major nerve supply to the gastrointestinal tract and controls GI tract motility. According to preclinical studies, 30% of myenteric plexus' neurons are enteric sensory neurons, thus Auerbach's plexus has also a sensory component. Structure A part of the enteric nervous sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscular Layer
The muscular layer (muscular coat, muscular fibers, muscularis propria, muscularis externa) is a region of muscle in many organs in the vertebrate body, adjacent to the submucosa. It is responsible for gut movement such as peristalsis. The Latin, tunica muscularis, may also be used. Structure It usually has two layers of smooth muscle: * inner and "circular" * outer and "longitudinal" However, there are some exceptions to this pattern. * In the stomach there are three layers to the muscular layer. Stomach contains an additional oblique muscle layer just interior to circular muscle layer. * In the upper esophagus, part of the externa is ''skeletal muscle'', rather than smooth muscle. * In the vas deferens of the spermatic cord, there are three layers: inner longitudinal, middle circular, and outer longitudinal. * In the ureter the smooth muscle orientation is opposite that of the GI tract. There is an inner longitudinal and an outer circular layer. The inner layer of the muscul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. Dopamine constitutes about 80% of the catecholamine content in the brain. It is an amine synthesized by removing a carboxyl group from a molecule of its precursor chemical, L-DOPA, which is synthesized in the brain and kidneys. Dopamine is also synthesized in plants and most animals. In the brain, dopamine functions as a neurotransmitter—a chemical released by neurons (nerve cells) to send signals to other nerve cells. Neurotransmitters are synthesized in specific regions of the brain, but affect many regions systemically. The brain includes several distinct dopamine pathways, one of which plays a major role in the motivational component of reward-motivated behavior. The anticipation of most types of rewards increases the level of dopamine in the brain, and many ad ... [...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] |
Leopold Auerbach
Leopold Auerbach (27 April 1828 – 30 September 1897) was a German anatomist and neuropathologist born in Breslau. Education and career Auerbach studied medicine at the Universities of Breslau, Berlin and the Leipzig. He became a physician in 1849, obtained his habilitation in 1863. From 1872 he was an associate professor of neuropathology at the University of Breslau. Discoveries Auerbach was among the first physicians to diagnose the nervous system using histological staining methods. He published a number of papers on neuropathological problems and muscle-related disorders. He is credited with the discovery of ''Plexus myentericus Auerbachi'', or Auerbach's plexus, a layer of ganglion cells that provide control of movements of the gastro-intestinal tract, also known as the "myenteric plexus". "Friedreich–Auerbach disease" is named after Auerbach and pathologist Nikolaus Friedreich (1825-1882). It is a rare disease characterized by hemi-hypertrophy of the facial features ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parkinson's Disease
Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms become more common. The most obvious early symptoms are tremor, rigidity, slowness of movement, and difficulty with walking. Cognitive and behavioral problems may also occur with depression, anxiety, and apathy occurring in many people with PD. Parkinson's disease dementia becomes common in the advanced stages of the disease. Those with Parkinson's can also have problems with their sleep and sensory systems. The motor symptoms of the disease result from the death of cells in the substantia nigra, a region of the midbrain, leading to a dopamine deficit. The cause of this cell death is poorly understood, but involves the build-up of misfolded proteins into Lewy bodies in the neurons. Collectively, the main motor symptoms are also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achalasia
Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esophagus. Achalasia can happen at various points along the gastrointestinal tract; achalasia of the rectum, for instance, may occur in Hirschsprung's disease. The lower esophageal sphincter is a muscle between the esophagus and stomach that opens when food comes in. It closes to avoid stomach acids from coming back up. A fully understood cause to the disease is unknown, as are factors that increase the risk of its appearance. Suggestions of a genetically transmittable form of achalasia exist, but this is neither fully understood, nor agreed upon. Esophageal achalasia is an esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES). It is characterized by incomplete LES relaxatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroblast
In vertebrates, a neuroblast or primitive nerve cell is a postmitotic cell that does not divide further, and which will develop into a neuron after a migration phase. In invertebrates such as ''Drosophila,'' neuroblasts are neural progenitor cells which divide asymmetrically to produce a neuroblast, and a daughter cell of varying potency depending on the type of neuroblast. Vertebrate neuroblasts differentiate from radial glial cells and are committed to becoming neurons. Neural stem cells, which only divide symmetrically to produce more neural stem cells, transition gradually into radial glial cells. Radial glial cells, also called radial glial progenitor cells, divide asymmetrically to produce a neuroblast and another radial glial cell that will re-enter the cell cycle. This mitosis occurs in the germinal neuroepithelium (or germinal zone), when a radial glial cell divides to produce the neuroblast. The neuroblast detaches from the epithelium and migrates while the radia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hirschsprung's Disease
Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Symptoms usually become apparent in the first two months of life. Complications may include enterocolitis, megacolon, bowel obstruction and intestinal perforation. The disorder may occur by itself or in association with other genetic disorders such as Down syndrome or Waardenburg syndrome. About half of isolated cases are linked to a specific genetic mutation, and about 20% occur within families. Some of these occur in an autosomal dominant manner. The cause of the remaining cases is unclear. If otherwise normal parents have one child with the condition, the next child has a 4% risk of being affected. The condition is divided into two main types, short-segment and long-segment, depending on how much of the bowel is affected. Rarely, the small bow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gustducin
Gustducin is a G protein associated with taste and the gustatory system, found in some taste receptor cells. Research on the discovery and isolation of gustducin is recent. It is known to play a large role in the transduction of bitter, sweet and umami stimuli. Its pathways (especially for detecting bitter stimuli) are many and diverse. An intriguing feature of gustducin is its similarity to transducin. These two G proteins have been shown to be structurally and functionally similar, leading researchers to believe that the sense of taste evolved in a similar fashion to the sense of sight. Gustducin is a heterotrimeric protein composed of the products of the GNAT3 (α-subunit), GNB1 (β-subunit) and GNG13 (γ-subunit). Discovery Gustducin was discovered in 1992 when degenerate oligonucleotide primers were synthesized and mixed with a taste tissue cDNA library. The DNA products were amplified by the polymerase chain reaction method, and eight positive clones were sh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TAS1R3
Taste receptor type 1 member 3 is a protein that in humans is encoded by the ''TAS1R3'' gene. The ''TAS1R3'' gene encodes the human homolog of mouse Sac taste receptor, a major determinant of differences between sweet-sensitive and -insensitive mouse strains in their responsiveness to sucrose, saccharin, and other sweeteners. Structure The protein encoded by the ''TAS1R3'' gene is a G protein-coupled receptor with seven trans-membrane domains and is a component of the heterodimeric amino acid taste receptor TAS1R1+3 and sweet taste receptor TAS1R2+3. This receptor is formed as a protein dimer with either TAS1R1 or TAS1R2. Experiments have also shown that a homo-dimer of TAS1R3 is also sensitive to natural sugar substances. This has been hypothesized as the mechanism by which sugar substitutes do not have the same taste qualities as natural sugars. Ligands The G protein-coupled receptors for sweet and umami taste are formed by dimers of the TAS1R proteins. The TAS1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-HT4 Receptor
5-Hydroxytryptamine receptor 4 is a protein that in humans is encoded by the ''HTR4'' gene. Function This gene is a member of the family of human serotonin receptors, which are G protein-coupled receptors that stimulate cAMP production in response to serotonin (5-hydroxytryptamine). The gene product is a glycosylated transmembrane protein that functions in both the peripheral and central nervous system to modulate the release of various neurotransmitters. Multiple transcript variants encoding proteins with distinct C-terminal sequences have been described, but the full-length nature of some transcript variants has not been determined. Location The receptor is located in the alimentary tract, urinary bladder, heart and adrenal gland as well as the central nervous system (CNS). In the CNS the receptor appears in the putamen, caudate nucleus, nucleus accumbens, globus pallidus, and substantia nigra, and to a lesser extent in the neocortex, raphe, pontine nuclei, and some a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substance P
Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its closely related neurokinin A (NKA) are produced from a polyprotein precursor after differential splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows: * Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met (RPKPQQFFGLM) with an amidation at the C-terminus. Substance P is released from the terminals of specific sensory nerves. It is found in the brain and spinal cord and is associated with inflammatory processes and pain. Discovery The original discovery of Substance P (SP) was in 1931 by Ulf von Euler and John H. Gaddum as a tissue extract that caused intestinal contraction ''in vitro''. Its tissue distribution and biologic actions were further investigated over the following decades. The e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
