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Afferent Pathways definition: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.
Afferent Pathway definition: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center. (MeSH)
auditory pathway definition: cochlear nuclei give rise to two bundles, the trapezoid body and dorsal acoustic stria, which rejoin as the lateral lemniscus and continue via the inferior colliculus to the auditory cortex.
Efferent Pathways definition: Nerve structures through which impulses are conducted from a nerve center toward a peripheral site. Such impulses are conducted via efferent neurons (NEURONS, EFFERENT), such as MOTOR NEURONS, autonomic neurons, and hypophyseal neurons.
Efferent Pathway definition: Nerve structures through which impulses are conducted from a nerve center toward a peripheral site. (MeSH)
Neural Pathways definition: Neural tracts connecting one part of the nervous system with another.
Neural Pathway definition: Neural tracts connecting one part of the nervous system with another. (MeSH)
Olfactory Pathways definition: Set of nerve fibers conducting impulses from olfactory receptors to the cerebral cortex. It includes the OLFACTORY NERVE; OLFACTORY BULB; olfactory tract, olfactory tubercle, anterior perforated substance, and olfactory cortex. The term rhinencephalon is restricted to structures in the CNS receiving fibers from the olfactory bulb.
pentose phosphate shunt definition: pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final one being an oxidative decarboxylation to form a pentose phosphate.
pentose-phosphate shunt definition: The process by which glucose is oxidized, coupled to NADPH synthesis. Glucose 6-P is oxidized with the formation of carbon dioxide (CO2), ribulose 5-phosphate and reduced NADP; ribulose 5-P then enters a series of reactions interconverting sugar phosphates. The pentose phosphate pathway is a major source of reducing equivalents for biosynthesis reactions and is also important for the conversion of hexoses to pentoses. [ISBN:0198506732 "Oxford Dictionary of Biochemistry and Molecular Biology", MetaCyc:PENTOSE-P-PWY]
Pentose Phosphate Pathway definition: An oxidative decarboxylation process that converts GLUCOSE-6-PHOSPHATE to D-ribose-5-phosphate via 6-phosphogluconate. The pentose product is used in the biosynthesis of NUCLEIC ACIDS. The generated energy is stored in the form of NADPH. This pathway is prominent in tissues which are active in the synthesis of FATTY ACIDS and STEROIDS.
Visual Pathways definition: Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.
visual pathway definition: sensory pathway for sight, conducting impulses from the photoreceptors to the cerebral cortex by way of the optic nerve, optic tract, and optic radiation.
Signaling Pathway definition: An elaboration of the known or inferred interactions involved in a signal transduction pathway.
Autonomic Pathways definition: Nerves and plexuses of the autonomic nervous system. The central nervous system structures which regulate the autonomic nervous system are not included.
Clinical Pathway definition: A defined set of diagnostic tests, treatments, and other interventions (including palliative care) for different types and stages of cancer.
Critical Pathways definition: Schedules of medical and nursing procedures, including diagnostic tests, medications, and consultations designed to effect an efficient, coordinated program of treatment. (From Mosby's Medical, Nursing & Allied Health Dictionary, 4th ed)
Embden-Meyerhof pathway definition: The main pathway for anaerobic degradation of carbohydrates. Starch or glycogen is hydrolyzed to glucose 1-phosphate and then through a series of intermediates, yielding two ATP molecules per glucose and producing either pyruvate (which feeds into the tricarboxylic acid cycle) or lactate. [http://cancerweb.ncl.ac.uk/]
Embden-Meyerhof Pathway definition: An old term for glycolysis. Often it is used to describe anaerobic glucose catabolism that includes the further conversion of PYRUVIC ACID to LACTIC ACID or ETHANOL.
Perforant Pathway definition: A pathway of fibers that originates in the lateral part of the ENTORHINAL CORTEX, perforates the SUBICULUM of the HIPPOCAMPUS, and runs into the stratum moleculare of the hippocampus, where these fibers synapse with others that go to the DENTATE GYRUS where the pathway terminates. It is also known as the perforating fasciculus.
Perforant Pathway definition: A pathway of fibers originating in the lateral part of the entorhinal area, perforating the subiculum of the hippocampus, and running into the stratum moleculare of the hippocampus, where these fibers synapse with others that go to the dentate gyrus. It is also called the perforating fasciculus. (MeSH)
Complement Pathway, Mannose-Binding Lectin definition: Complement activation triggered by the interaction of microbial POLYSACCHARIDES with serum MANNOSE-BINDING LECTIN resulting in the activation of MANNOSE-BINDING PROTEIN-ASSOCIATED SERINE PROTEASES. As in the classical pathway, MASPs cleave COMPLEMENT C4 and COMPLEMENT C2 to form C3 CONVERTASE (C4B2A) and the subsequent C5 CONVERTASE (C4B2A3B) leading to cleavage of COMPLEMENT C5 and assembly of COMPLEMENT MEMBRANE ATTACK COMPLEX.
Secretory Pathway definition: A series of sequential intracellular steps involved in the transport of proteins (such as hormones and enzymes) from the site of synthesis to outside the cell. The pathway involves membrane-bound compartments through which the newly synthesized proteins undergo POST-TRANSLATIONAL MODIFICATIONS, packaging, storage, or transportation to the PLASMA MEMBRANE for secretion.
secretory pathway definition: OBSOLETE. The pathway along which proteins and other substances are moved around and out of the cell. After synthesis on the ribosomes of the endoplasmic reticulum (ER), completed polypeptide chains are moved to the Golgi complex and subsequently sorted to various destinations. Proteins synthesized and sorted in the secretory pathway include not only those that are secreted from the cell but also enzymes and other resident proteins in the lumen of the ER, Golgi, and lysosomes as well as integral proteins in the membranes of these organelles and the plasma membrane. [ISBN:0716731363]
Metabolic Pathway definition: An elaboration of the known steps and interactions for the metabolism of a compound.
other pathways of electron transport definition: OBSOLETE (was not defined before being made obsolete). [GOC:go_curators]
Arginine, Histidine, Glutamate, Glutamine, and Proline Degradation Pathway definition: Glutamine is converted to glutamate by glutaminase, or several other enzymes, by the removal of the amide nitrogen. Proline is first converted to a Schiff base and then converted by hydrolysis to glutamate-5-semialdehyde. All of these changes occur on the same carbon. Arginine and histidine contain 5 adjacent carbons and a sixth carbon attached through a nitrogen atom. The catabolism of these amino acids is thus slightly more complicated than glutamine or proline. Arginine is converted to ornithine and urea. Ornithine is further transaminated to produce glutamate-5-semialdehyde. Glutamate-5-semialdehyde is converted to glutamate. Tetrahydrofolate is the cofactor in the final step converting histidine to glutamate. Transamination or deamination of glutamate produces a-ketoglutarate which feeds into the citric acid cycle. (BioCarta)
Human Cytomegalovirus Infection Pathway definition: To replicate in host cell, viruses commandeer cellular signaling pathways. Cytomegalovirus (CMV) is a DNA virus that is widespread in the population but usually causes disease only in immunocompromised individuals and is also a viral cause of birth defects. One of the actions of CMV in the host cell is to stimulate MAP kinase pathways. Both p38 and ERK kinases are activated by CMV infection through activation of map kinase kinases and inhibition of phosphatases. One result of Map kinase activation by CMV is activation of transcription of viral genes, increasing the production of viral gene products. Both p38 and ERK kinases contribute to the activation of viral genes by cellular transcription factors acting through the viral UL4 promoter at upstream and basal transcription elements. Another target of prolonged p38 activation during infection is Rb, contributing to viral replication. Activation of MKK1 and MKK2 leads to Erk1 and Erk2 activation, and phosphorylation of downstream targets. The MEKK1 kinase regulates the immediate early promoter indirectly through downstream kinase signaling and perhaps more directly through activation of NF-kB. Map kinase pathways activated by CMV converge on increased transcription of viral genes and increased replication of the viral genome. Better understanding of the mechanisms involved in the interaction of CMV with cellular signaling machinery will provide improved ways to treat CMV-mediated disease. (BioCarta)
IGF1R Antiapoptosis Pathway definition: IGF-1R, the type 1 receptor for insulin-like growth factor, mediates cell survival and growth in response to its ligands IGF-1 and IGF-2. This tyrosine kinase receptor is widely expressed in many cell types and is a key mediator of growth. Overexpression or activation of IGF-1R may be involved in the proliferation of transformed cells, making inhibition of IGF-1R signaling a strategy for the development of cancer drugs. IGF-1R activates three signaling pathways that converge to phosphorylate BAD protein and block apoptosis. The first pathway activated by IGF-1R stimulates PI3-kinase and the AKT pathway to phosphorylate BAD and block apoptosis. A second pathway activated by IGF-1R involves ras mediated activation of the map kinase pathway to block apoptosis. A third pathway involves interaction of raf with mitochondria in response to IGF-1R activation. The convergence of these pathways to block apoptosis may enhance the IGF-1R response. (BioCarta)
Methionine, Isoleucine, Threonine and Valine Degradation Pathway definition: The carbon chains of methionine, isoleucine, threonine, and valine are broken down to produce succinyl-CoA, which feeds into the Citric Acid Cycle. Methionine donates its methyl group via S-adenosylmethionine to one of several acceptors and the four remaining carbons are the backbone of propionyl-CoA that is subsequently converted to succinyl-CoA. The transdeamination and decarboxylation of valine are followed by a series of steps resulting in the formation of propionyl-CoA. Isoleucine also undergoes transdeamination, followed by oxidative decarboxylation. These steps yield propionyl-CoA as well as acetyl-CoA. Deficiency in the steps that convert isoleucine to propionyl-CoA causes sudden unexplained infant death, Reye-like syndrome, cardiomyopathy, and skeletal myopathy. (BioCarta)
Modeling of Cellular Pathways definition: Any representation of the individual steps in a metabolic pathway of a cell.
MAP Kinase Regulation Pathway definition: Mitogen-activated protein (MAP) kinases are important players in signal transduction pathways activated by a range of stimuli and mediate a number of physiological and pathological changes in cell function. There are three major subgroups in the MAPK family: ERK, p38, and JNK/SAPK. ERK is activated mainly by mitogenic stimuli, whereas p38 and JNK/SAPK are activated mainly by stress stimuli or inflammatory cytokines. MAP kinases are part of a three-tiered phosphorylation cascade and MAP kinase phosphorylation on a threonine and tyrosine residue located within the activation loop of kinase subdomain VIII results in activation. However, this process is reversible even in the continued presence of activating stimuli, indicating that protein phosphatases provide an important mechanism for MAP kinase control. Dual specificity phosphatases (DSPs) from the tyrosine phosphatase (PTP) gene superfamily are selective for dephosphorylating the critical phosphothreonine and phosphotyrosine residues within MAP kinases. Ten members of dual specificity phosphatases specifically acting on MAPKs, termed MAPK phosphatases (MKPs), have been reported. They share sequence homology and are highly specific for MAPKs but differ in the substrate specificity, tissue distribution, subcellular localization, and inducibility by extracellular stimuli. MKPs have been shown to play important roles in regulating the function of the MAPK family. DSP gene expression is induced strongly by various growth factors and/or cellular stresses. Expression of some gene family members, including CL100/MKP-1, hVH-2/MKP-2, and PAC1, is dependent at least in part on MAP kinase activation providing negative feedback for the inducing MAP kinase or for regulatory cross talk between parallel MAP kinase pathways. DSPs are localized to different subcellular compartments and certain family members appear highly selective for inactivating distinct MAP kinase isoforms. This enzymatic specificity is due to catalytic activation of the DSP phosphatase after tight binding of its amino-terminal to the target MAP kinase. Thus, DSP phosphatases provide a sophisticated mechanism for targeted inactivation of selected MAP kinase activities. (BioCarta)
Biochemical Pathway definition: An elaboration of the sequence of chemical reactions leading from one compound to another taking place in living tissue.
Pathway definition: A set or series of interactions, often forming a network, which biologists have found useful to group together for organizational, historic, biophysical, or other reasons.
Metabolic Networks and Pathways definition: Complex sets of enzymatic reactions connected to each other via their product and substrate metabolites.
Biosynthetic Pathways definition: Sets of enzymatic reactions occurring in organisms and that form biochemicals by making new covalent bonds.