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Grey Column
The grey column refers to a somewhat ridge-shaped mass of grey matter in the spinal cord. This presents as three columns: the anterior grey column, the posterior grey column, and the lateral grey column, all of which are visible in cross-section of the spinal cord. The anterior grey column is made up of alpha motor neurons, gamma motor neurons, and small neurons thought to be interneurons. The posterior grey column is divided into several of the Rexed laminae. The lateral grey column is only present in the thoracic region and upper lumbar segments (T1-L2). The lateral grey column contains preganglionic cell bodies of the autonomic nervous system and sensory relay neurons. Structure Anterior grey column The anterior grey column, also known as the anterior horn of spinal cord, comprises three different types of neurons: large alpha motor neurons, medium gamma motor neurons, and small neurons thought to be interneurons. These neurons differ in both their morphology and in their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuskegee, Alabama
Tuskegee () is a city in Macon County, Alabama, United States. It was founded and laid out in 1833 by General Thomas Simpson Woodward, a Creek War veteran under Andrew Jackson, and made the county seat that year. It was incorporated in 1843. It is the largest city in Macon County. At the 2020 census the population was 9,395, down from 9,865 in 2010 and 11,846 in 2000. Tuskegee has been important in African-American history and highly influential in United States history since the 19th century. Before the American Civil War, the area was developed for cotton plantations, dependent on enslaved African-American people. After the war, many freedmen continued to work on plantations in the rural area, which was devoted to agriculture, primarily cotton as a commodity crop. In 1881 the Tuskegee Normal School (now Tuskegee University, a historically black college) was founded by Lewis Adams, a former slave whose father, Jesse Adams, a white slave owner, had allowed him to be educate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrafusal Muscle Fibers
Extrafusal muscle fibers are the standard skeletal muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement. They make up the large mass of skeletal striated muscle tissue and are attached to bone by fibrous tissue extensions (tendons). Each alpha motor neuron and the extrafusal muscle fibers innervated by it make up a motor unit. The connection between the alpha motor neuron and the extrafusal muscle fiber is a neuromuscular junction, where the neuron's signal, the action potential, is transduced to the muscle fiber by the neurotransmitter acetylcholine. Extrafusal muscle fibers are not to be confused with intrafusal muscle fibers, which are innervated by sensory nerve endings in central noncontractile parts and by gamma motor neurons in contractile ends and thus serve as a sensory proprioceptor. Extrafusal muscle fibers can be generated in vitro (in a dish) from pluripotent stem cells through dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudal Ventrolateral Medulla
The ventrolateral medulla, part of the medulla oblongata of the brainstem, plays a major role in regulating arterial blood pressure and breathing. It regulates blood pressure by regulating the activity of the sympathetic nerves that target the heart and peripheral blood vessels. The ventrolateral medulla consists of a rostral ventrolateral medulla (RVLM) and a caudal ventrolateral medulla (CVLM). Neurons in the RVLM project directly to preganglionic neurons in the spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ... and maintain tonic activity in the sympathetic vasomotor nerves. This activity is inhibited by GABA output from the CVLM. References Sympathetic nervous system Reflexes Medulla oblongata Cardiovascular physiology {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marginal Nucleus Of Spinal Cord
The marginal nucleus of spinal cord, or posteromarginal nucleus, Rexed lamina I, is located at the most dorsal aspect of the posterior horn of spinal cord, dorsal horn of the spinal cord. The neurons located here receive input primarily from Lissauer's tract and relay information related to pain and temperature sensation. Pain sensation relayed here cannot be modulated, e.g. pain from burning the skin. The axons of neurons contribute to the lateral spinothalamic tract. Back anatomy Spinal cord {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medulla Spinalis - Substantia Grisea - English
Medulla or Medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ovary * Medulla of the thymus, a part of the lobes of the thymus * Medulla of lymph node * Medulla (hair), the innermost layer of the hair shaft * Medulla, a part of the optic lobe of arthropods * Medulla (lichenology), a layer of the internal structure of a lichen * Pith, or medulla, a tissue in the stems of vascular plants Other uses * ''Medúlla'', a 2004 album by Björk * Medulla, Florida, a place in the U.S. * Las Médulas, a gold mining site in León, Spain See also * *Medullary cavity The medullary cavity (''medulla'', innermost part) is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow ( adipose tissue) is stored; hence, the medullary cavity is also known as the marrow cavity. Located in the m ..., the central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nociception
Nociception (also nocioception, from Latin ''nocere'' 'to harm or hurt') is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal in order to trigger an appropriate defense response. In nociception, intense chemical (e.g., capsaicin present in Chili pepper or Cayenne pepper), mechanical (e.g., cutting, crushing), or thermal (heat and cold) stimulation of sensory neurons called nociceptors produces a signal that travels along a chain of nerve fibers via the spinal cord to the brain. Nociception triggers a variety of physiological and behavioral responses to protect the organism against an aggression and usually results in a subjective experience, or perception, of pain in Sentience, sentient beings. Detection of noxious stimuli Potentially damaging mecha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haptic Perception
Haptic perception ( gr, haptόs, script=latn, italics=yes "palpable", ''haptikόs'' "suitable for touch") means literally the ability "to grasp something". Perception in this case is achieved through the active exploration of surfaces and objects by a moving subject, as opposed to passive contact by a static subject during ''tactile perception''.Weber, E. H. (1851). ''Die Lehre vom Tastsinne und Gemeingefühle auf Versuche gegründet''. Friedrich Vieweg und Sohn. History The term ''haptik'' was coined by the German Psychologist Max Dessoir in 1892, when suggesting a name for academic research into the sense of touch in the style of that in "acoustics" and "optics". Gibson (1966) defined the haptic system as " e sensibility of the individual to the world adjacent to his body by use of his body". Gibson and others further emphasized what Weber had realized in 1851: the close link between haptic perception and body movement, and that haptic perception is active exploration. The co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afferent Neurons
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal ganglia of the spinal cord. The sensory information travels on the afferent nerve fibers in a sensory nerve, to the brain via the spinal cord. The stimulus can come from ''exteroreceptors'' outside the body, for example those that detect light and sound, or from ''interoreceptors'' inside the body, for example those that are responsive to blood pressure or the sense of body position. Types and function Different types of sensory neurons have different sensory receptors that respond to different kinds of stimuli. There are at least six external and two internal sensory receptors: External receptors External receptors that respond to stimuli from outside the body are called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inhibitory Postsynaptic Potential
An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential.Purves et al. Neuroscience. 4th ed. Sunderland (MA): Sinauer Associates, Incorporated; 2008. IPSP were first investigated in motorneurons by David P. C. Lloyd, John Eccles and Rodolfo Llinás in the 1950s and 1960s. The opposite of an inhibitory postsynaptic potential is an excitatory postsynaptic potential (EPSP), which is a synaptic potential that makes a postsynaptic neuron ''more'' likely to generate an action potential. IPSPs can take place at all chemical synapses, which use the secretion of neurotransmitters to create cell to cell signalling. Inhibitory presynaptic neurons release neurotransmitters that then bind to the postsynaptic receptors; this induces a change in the permeability of the postsynaptic neuronal membrane to particular ions. An electric current that changes the postsynaptic membrane potential to create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excitatory Postsynaptic Potential
In neuroscience, an excitatory postsynaptic potential (EPSP) is a postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential. This temporary depolarization of postsynaptic membrane potential, caused by the flow of positively charged ions into the postsynaptic cell, is a result of opening ligand-gated ion channels. These are the opposite of inhibitory postsynaptic potentials (IPSPs), which usually result from the flow of ''negative'' ions into the cell or positive ions ''out'' of the cell. EPSPs can also result from a decrease in outgoing positive charges, while IPSPs are sometimes caused by an increase in positive charge outflow. The flow of ions that causes an EPSP is an excitatory postsynaptic current (EPSC). EPSPs, like IPSPs, are graded (i.e. they have an additive effect). When multiple EPSPs occur on a single patch of postsynaptic membrane, their combined effect is the sum of the individual EPSPs. Larger EPSPs result in greater membr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muscle Spindles
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be processed by the brain as proprioception. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, for example, by activating motor neurons via the stretch reflex to resist muscle stretch. The muscle spindle has both sensory and motor components. * Sensory information conveyed by primary type Ia sensory fibers which spiral around muscle fibres within the spindle, and secondary type II sensory fibers * Activation of muscle fibres within the spindle by up to a dozen gamma motor neurons and to a lesser extent by one or two beta motor neurons Structure Muscle spindles are found within the belly of a skeletal muscle. Muscle spindles are fusiform (spindle-shaped), and the sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrafusal Muscle Fibers
Intrafusal muscle fibers are skeletal muscle fibers that serve as specialized sensory organs (proprioceptors). They detect the amount and rate of change in length of a muscle.Casagrand, Janet (2008) ''Action and Movement: Spinal Control of Motor Units and Spinal Reflexes.'' University of Colorado, Boulder. They constitute the muscle spindle, and are innervated by both sensory (afferent) and motor (efferent) fibers. Intrafusal muscle fibers are not to be confused with extrafusal muscle fibers, which contract, generating skeletal movement and are innervated by alpha motor neurons. Structure Types There are two types of intrafusal muscle fibers: nuclear bag fibers and nuclear chain fibers. They bear two types of sensory ending, known as annulospiral and flower-spray endings. Both ends of these fibers contract, but the central region only stretches and does not contract. Intrafusal muscle fibers are walled off from the rest of the muscle by an outer connective tissue she ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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