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Terminal Cisterna
Terminal cisternae (singular: terminal cisterna) are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules. Function Terminal cisternae are discrete regions within the muscle cell. They store calcium (increasing the capacity of the sarcoplasmic reticulum to release calcium) and release it when an action potential courses down the transverse tubules, eliciting muscle contraction. Because terminal cisternae ensure rapid calcium delivery, they are well developed in muscles that contract quickly, such as fast twitch skeletal muscle. Terminal cisternae then go on to release calcium, which binds to troponin. This releases tropomyosin, exposing active sites of the thin filament, actin. There are several mechanisms directly linked to the terminal cisternae which facilitate excitation-contraction coupling. When excitation of the membrane arrives at the T-tubule nearest the muscle fiber, a dihydropyridine channel ( DHP channel) is activated. This is simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Blausen 0801 SkeletalMuscle
Blausen Medical Communications, Inc. (BMC) is the creator and owner of a library of two- and three-dimensional medical and scientific images and animations, a developer of information technology allowing access to that content, and a business focused on licensing and distributing the content. It was founded by Bruce Blausen in Houston, Texas, in 1991, and is privately held. Background Blausen Medical Communications is a privately held company founded by Bruce Blausen in Houston, Texas in 1991. BMC created and owns a library of medical and scientific images and animations, and has developed information technology tools allowing access to the library; as well, it licenses and otherwise works to distribute the content. As of this date, BMC's animation library comprised approximately 1,500 animations and over 27,000 two- and three-dimensional images designed for point-of-care patient education, which could be accessed by consumers or professional caregivers (primarily via hospital o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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DHP Channel
Cav1.1 also known as the calcium channel, voltage-dependent, L type, alpha 1S subunit, (CACNA1S), is a protein which in humans is encoded by the ''CACNA1S'' gene. It is also known as CACNL1A3 and the dihydropyridine receptor (DHPR, so named due to the blocking action DHP has on it). Function This gene encodes one of the five subunits of the slowly inactivating L-type voltage-dependent calcium channel in skeletal muscle cells. Mutations in this gene have been associated with hypokalemic periodic paralysis, thyrotoxic periodic paralysis and malignant hyperthermia susceptibility. Cav1.1 is a voltage-dependent calcium channel found in the transverse tubule of muscles. In skeletal muscle it associates with the ryanodine receptor RyR1 of the sarcoplasmic reticulum via a mechanical linkage. It senses the voltage change caused by the end-plate potential from nervous stimulation and propagated by sodium channels as action potentials to the T-tubules. It was previously thought tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Splanchnic Nerve
The splanchnic nerves are paired visceral nerves (nerves that contribute to the innervation of the internal organs), carrying fibers of the autonomic nervous system ( visceral efferent fibers) as well as sensory fibers from the organs ( visceral afferent fibers). All carry sympathetic fibers except for the pelvic splanchnic nerves, which carry parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ... fibers. Types The term ''splanchnic nerves'' can refer to: * Cardiopulmonary nervesEssential Clinical Anatomy. K.L. Moore & A.M. Agur. Lippincott, 3 ed. 2007. Page 181 * Thoracic splanchnic nerves (greater, lesser, and least) * Lumbar splanchnic nerves * Sacral splanchnic nerves * Pelvic splanchnic nerves See also * Terminal cisterna * Rexed lamina * Pregangl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Postganglionic Nerve Fiber
In the autonomic nervous system, nerve fibers from the ganglion to the effector organ are called postganglionic nerve fibers. Neurotransmitters The neurotransmitters of postganglionic fibers differ: * In the parasympathetic division, neurons are '' cholinergic''. That is to say acetylcholine is the primary neurotransmitter responsible for the communication between neurons on the parasympathetic pathway. * In the sympathetic division, neurons are mostly ''adrenergic'' (that is, epinephrine and norepinephrine function as the primary neurotransmitters). Notable exceptions to this rule include the sympathetic innervation of sweat glands and arrectores pilorum muscles where the neurotransmitter at both pre and post ganglionic synapses is acetylcholine. Another notable structure is the medulla of the adrenal gland, where chromaffin cells function as modified post-ganglionic nerves. Instead of releasing epinephrine and norepinephrine into a synaptic cleft, these cells of the adren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Preganglionic Nerve Fiber
In the autonomic nervous system, nerve fibers from the central nervous system to the ganglion are known as preganglionic nerve fibers. All preganglionic fibers, whether they are in the sympathetic division or in the parasympathetic division, are cholinergic (that is, these fibers use acetylcholine as their neurotransmitter) and they are myelinated. Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the parasympathetic ganglia. Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons. See also * Nerve fiber * Grey column * Terminal cisterna * Rexed lamina * Postganglionic nerve fiber * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rexed Lamina
The Rexed laminae (singular: Rexed lamina) comprise a system of ten layers of grey matter (I–X), identified in the early 1950s by Bror Rexed to label portions of the grey columns of the spinal cord. Similar to Brodmann areas, they are defined by their cellular structure rather than by their location, but the location still remains reasonably consistent. Laminae * Posterior grey column: I–VI ** Lamina I: marginal nucleus of spinal cord or posteromarginal nucleus ** Lamina II: substantia gelatinosa of Rolando ** Laminae III and IV: nucleus proprius ** Lamina V: Neck of the dorsal horn. Neurons within lamina V are mainly involved in processing sensory afferent stimuli from cutaneous, muscle and joint mechanical nociceptors as well as visceral nociceptors. This layer is home to wide dynamic range tract neurons, interneurons and propriospinal neurons. Viscerosomatic pain signal convergence often occurs in this lamina due to the presence of wide dynamic range tract neurons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Cistern Of Lamina Terminalis
The cistern of lamina terminalis is one of the subarachnoid cisterns. It is situated (depending upon the source) either superior to the lamina terminalis, or rostral/anterior to the lamina terminalis and anterior commissure between the two frontal lobes of the cerebrum. It is situated rostral/anterior to the third ventricle. The cistern is an extension of interpeduncular cistern. The cistern of lamina terminalis interconnects the chiasmatic cistern and pericallosal cistern. The cistern contains the anterior cerebral arteries, the anterior communicating artery, hypothalamic artery, the origin of the fronto-orbital arteries, and Heubner's artery. See also * Terminal cisterna Terminal cisternae (singular: terminal cisterna) are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubules. Function Terminal cisternae are discrete regions within the muscle cell. They store calcium (increasing t ... References Meninges {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Action Potential
An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of Membrane potential#Cell excitability, excitable cells, which include animal cells like neurons and myocyte, muscle cells, as well as some plant cells. Certain endocrine cells such as pancreatic beta cells, and certain cells of the anterior pituitary gland are also excitable cells. In neurons, action potentials play a central role in cell–cell interaction, cell–cell communication by providing for—or with regard to saltatory conduction, assisting—the propagation of signals along the neuron's axon toward axon terminal, synaptic boutons situated at the ends of an axon; these signals can then connect wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Triad (anatomy)
In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side. Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally. (This property holds because T tubules run perpendicular to the longitudinal axis of the muscle fiber.) In mammals, triads are typically located at the A-I junction; that is, the junction between the A and I bands of the sarcomere, which is the smallest unit of a muscle fiber. Triads form the anatomical basis of excitation-contraction coupling, whereby a stimulus excites the muscle and causes it to contract. A stimulus, in the form of positively charged current, is transmitted from the neuromuscular junction down the length of the T tubules, activating dihydropyridine receptors (DHPRs). Their activation causes 1) a negligible influx of calcium and 2) a mechanical interaction with calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Calcium
Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium. The most common calcium compound on Earth is calcium carbonate, found in limestone and the fossils of early sea life; gypsum, anhydrite, fluorite, and apatite are also sources of calcium. The name comes from Latin ''calx'' " lime", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ryanodine
Ryanodine is a poisonous diterpenoid found in the South American plant ''Ryania speciosa'' (Salicaceae). It was originally used as an insecticide. The compound has extremely high affinity to the open-form ryanodine receptor, a group of calcium channels found in skeletal muscle, smooth muscle, and heart muscle cells. It binds with such high affinity to the receptor that it was used as a label for the first purification of that class of ion channels and gave its name to it. At nanomolar concentrations, ryanodine locks the receptor in a half-open state, whereas it fully closes them at micromolar concentration. The effect of the nanomolar-level binding is that ryanodine causes release of calcium from calcium stores as the sarcoplasmic reticulum in the cytoplasm, leading to massive muscle contractions. The effect of micromolar-level binding is paralysis. This is true for both mammals and insects. See also * Diamide insecticides, a class of insecticides with the same mechanism of ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ligand-gated Ion Channel
Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as sodium, Na+, potassium, K+, calcium, Ca2+, and/or chloride, Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand (biochemistry), ligand), such as a neurotransmitter. When a presynaptic neuron is excited, it releases a neurotransmitter from vesicles into the synaptic cleft. The neurotransmitter then binds to receptors located on the postsynaptic neuron. If these receptors are ligand-gated ion channels, a resulting conformational change opens the ion channels, which leads to a flow of ions across the cell membrane. This, in turn, results in either a depolarization, for an excitatory receptor response, or a hyperpolarization (biology), hyperpolarization, for an inhibitory response. These receptor proteins are typically composed of at least two different domains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |