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Somatic nervous system

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	Somatic nervous system
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	Topics Somatic nervous system Topic Home The somatic nervous system is the part of the peripheral nervous systemPeripheral nervous system The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that resid... associated with the voluntary control of body movements through the action of skeletal muscles, and with receptionSensory receptor Overview In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of... of external stimuliFacts About Stimulus Stimulus may refer to:Stimulus , in physiology, is something external that elicits or influences a physiological or psych... , which helps keep the body in touch with its surroundings (e.g., touchTactition Tactition* is the sense of pressure perception. ... , hearingHearing (sense) Hearing, or audition, is one of the traditional five senses and refers to the ability to detect sound.... , and sightSight Sight may refer to one of the following:... ). The system includes all the neuronNeuron Neurons are a major class of cells in the nervous system.... s connected with muscleMuscle Muscle is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells.... s, skinSkin Summary In zootomy and dermatology, skin is an organ of the integumentary system made up of multiple layers of epithelial tissues th... and sense organsSensory system 'A sensory system is a part of the nervous system responsible for processing sensory information.... . The somatic nervous system consists of efferent nerveFacts About Efferent nerve In the nervous system, efferent nerves--otherwise known as motor or effector neuron--carry nerve impulses away from the ... s responsible for sending brain signals for muscle contractionMuscle contraction A muscle contraction occurs when a muscle cell shortens.... . Nerve signal transmission The somatic nervous system processes sensory information and controls all voluntary muscular systems within the body, with the exception of reflex arcReflex arc A reflex arc is the neural pathway that mediates a reflex action.... s. The basic route of nerve signals within the efferentFacts About Efferent Efferent can refer to:Efferent nerve... somatic nervous system involves a sequence that begins in the upper cell bodiesCell (biology) The cell* is the structural and functional unit of all living organisms, and is sometimes called the "building block of life.... of motor neuronMotor neuron In vertebrates, motor neurons are efferent neurons that originate in the spinal cord or brain stem and synapse with muscle f... s within the precentral gyrusBrodmann area 4 Brodmann area 4 comprises the primary motor cortex of the human brain.... (which approximates the primary motor cortexPrimary motor cortex The primary motor cortex works in association with pre-motor areas to plan and execute movements.... ). Stimuli from the precentral gyrus are transmitted from upper motor neurons and down the corticospinal tractCorticospinal tract The corticospinal or pyramidal tract is a massive collection of axons that travel between the cerebral cortex of the b... , via axonAxon Overview An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, that conducts electrical impulses aw... s to control skeletal (voluntary) muscles. These stimuli are conveyed from upper motor neurons through the ventral horn of the spinal cordSpinal cord In vertebrates, the spinal cord is the part of the central nervous system that is enclosed in and protected by the vertebral... , and across synapses to be received by the sensory receptorFacts About Sensory receptor In a sensory system, a sensory receptor is a structure that recognizes a stimulus in the internal or external environment of... s of alpha motor neuronAlpha motor neuron Alpha motor neurons are large lower motor neurons of the brainstem and spinal cord.... (large lower motor neuronLower motor neuron Lower motor neurons are the motoneurons connecting the brainstem and spinal cord to muscle fibers, bringing the nerve impuls... s) of the brainstem and spinal cordSpinal cord In vertebrates, the spinal cord is the part of the central nervous system that is enclosed in and protected by the vertebral... . Upper motor neurons release a neurotransmitterNeurotransmitter Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another... , acetylcholineAcetylcholine The chemical compound acetylcholine, often abbreviated as ACh, was the first neurotransmitter to be identified.... , from their axon terminal knobs, which are received by nicotinic receptorsNicotinic acetylcholine receptor Nicotinic acetylcholine receptors, or nAChRs, are ionotropic receptors that form ion channels in cells' plasma membran... of the alpha motor neurons. In turn, alpha motor neurons relay the stimuliFacts About Stimulus (physiology) In physiology, a stimulus is a detectable change in the internal or external environment.... received down their axons via the ventral rootVentral root In anatomy and neurology, the ventral root is the efferent motor root of a spinal nerve.... of the spinal cord. These signals then proceed to the neuromuscular junctionNeuromuscular junction A neuromuscular junction is the synapse or junction of the axon terminal of a motoneuron with the motor end plate, the highl... s of skeletal muscles. From there, acetylcholine is released from the axon terminal knobs of alpha motor neurons and received by postsynaptic receptorReceptor (biochemistry) Overview In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specif... s of muscles, thereby relaying the stimulus to contract muscle fibers. Vertebrate and invertebrate differences In invertebrates, depending on the neurotransmitter released and the type of receptor it binds, the response in the muscle fiber could either be excitatory or inhibitory. For vertebrateVertebrate Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns.... s, however, the response of a muscle fiber to a neurotransmitter (always acetylcholineAcetylcholine The chemical compound acetylcholine, often abbreviated as ACh, was the first neurotransmitter to be identified.... (ACh)) can only be excitatory or, in other words, contractile. Reflex arcs A reflex arcReflex arc A reflex arc is the neural pathway that mediates a reflex action.... is an automatic reaction that allows an organism to protect itself reflexReFLEX Overview ReFLEX is a wireless protocol developed by Motorola which is used for two-way paging.... ively when an imminent danger is perceived. In response to certain stimuli, such as touching a hot surface, these reflexes are 'hard wired' through the spinal cord. A reflexive impulse travels up afferent nerves, through a spinal interneuronInterneuron Overview An interneuron is a neuron that communicates only to other neurons.... , and back down appropriate efferent nerves. See also Autonomic nervous systemAutonomic nervous system The autonomic nervous system is the part of the nervous system that is not under conscious control.... Enteric nervous systemEnteric nervous system The enteric nervous system is an interdependent part of the autonomic nervous system....