ANAT 2646 Exam 2 Review - CNS EXAM 2 INNERVATION OF THE...

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CNS EXAM 2 INNERVATION OF THE SKIN Sensory Unit – the stem fiber and all of its endings, the entire neuron with cell body located in the DRG Receptive Field – small territory where a sensory unit can be excited, a small part of a dermatome Dermatome – a strip of skin innervated by a single spinal nerve, it has 1000s of nerve fibers Sensory Transduction – the transformation of a stimulus into an electrical signal Rapidly Adapting Receptors – Phasic receptors, respond quickly and maximally at the onset of the stimulus, but stop responding even if the stimulus continues. Essential in responding to changes, but ignore ongoing processes, such as the ignored continuous pressure of wearing a watch Slowly Adapting Receptors – Tonic receptors, continue to respond as long as the stimulus is present Receptors Classified by Stimulus Source: o Exteroceptors – close to the body’s surface, detect sensory information from the external environment (visual, olfactory, etc.), sensitive to touch, pressure, temperature, pain, and vibration o Proprioceptors – transmit sensory information from muscles, tendons, and joints about the position of a body part, such as a limb in space o Interoceptors – detect sensory information concerning the status of the body’s internal environment, such as stretch, BP, pH, oxygen or carbon dioxide concentration, and osmolarity Receptors Classified by Modality/Function: o Nociceptors – rapidly adapting receptors that are sensitive to noxious of painful stimuli o Thermoreceptors – sensitive to temperature, slowly adapting o Mechanoreceptors – detect physical deformation due to touch, stretch, pressure, and vibration Non-Encapsulated Free Nerve Endings – are found close to the surface, transmit pain and temperature (touch and pressure), slow adapting Follicular – aka peritrichial, coiled around hair follicles and respond when a hair is bent, touch, rapidly adapting Merkel’s Discs – aka tactile receptors, special epidermal cells with free nerve endings under them, respond to discriminative touch stimuli that facilitate the distinguishing of texture, shape, and the edges of objects, like holding a pencil, slow adapting Encapsulated
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Meissner’s Corpuscles – located in the papillae of the dermis, light touch (fine discrimination), rapidly adapting Pacinian Corpuscle – the largest skin receptor, no magnification needed to see it, located in the dermis, respond to pressure, tickling, and vibration, rapid adapt Ruffini’s End Organs – deeper pressure, shearing/drag, slowly adapting Sensory information from joints, muscles, and skin are integrated in the parietal lobe SPINAL REFLEXES Reflex – predictable response to a stimulation that is unconscious, few synapses are involved and it doesn’t go up to the cortex Motor Unit – the functional unit of the motor system, an alpha motor neuron with all of its branches and the muscle fibers it innervates, one neuron may innervate
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ANAT 2646 Exam 2 Review - CNS EXAM 2 INNERVATION OF THE...

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