3.3 - Mechanoreception.docx - 3.3 u2013 Mechanoreception...

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3.3 – Mechanoreception &HearingMechanoreceptors:-Mechanoreceptors are ion channels connected to the cytoskeletonoThis means that they’re mechanism of function is similar across many species including vertebrates and invertebratesoThe modality of stimuli the receptor is sensitive to depends on the connection of its extracellular link (ex. connection to a hair follicle will mean that air currents will be detected) oWhen a stimulus deforms the extracellular anchoring proteins the receptor is linked to the channel changes the flow of ions across cell membrane-Mechanoreceptors can be classified by what they detect two major categoriesoTouch and Pressure: Baroreceptors, Tactile Receptors, ProprioceptorsoEquilibrium and Hearing: Statocysts, Hair Cells, Neuromasts, ElectroreceptorsTouch and Pressure Receptors:-Baroreceptors: oVertebrates only oDetect changes in the pressure on epithelial walls in the body blood vessels, heart, digestive, reproductive and urinary tracts Carotid Sinus Baroreceptors blood pressure in the brain -Tactile Receptors: oDetect pressure, touch and vibration by definition found in the skin oFree Nerve Endings(Tonic): Dendrites in epidermis with receptor proteins attachedoMerkel’s Disks(Tonic): Enlarged epidermal cell (Merkel’s cell) associated with a single free nerve ending small receptive field = fine tactile discriminationoRoot hair plexus(Phasic): Small network of nerve endings surrounding base of hair follicle respond to movement of hair, detecting movements across bodies surfacePhases so they detect changes (can feel a bug crawling on your skin but not one standing on your skin)oPacinian Corpuscle(Phasic): Deep in skin (and in muscles/organs), made up of a sensory dendrite surrounded by layers of lamellae with a viscous gel between when deformed by pressure lamellae stimulate dendrite (see Intro to sensation) oRuffini Corpuscle(Tonic): Proprioceptor found in connective tissue of skin and joints/limbs sensitive to stretch of skin and body movement
-Proprioceptors: oMuscle Spindles: On the surface of skeletal muscles Intrafusal fibers (modifiedmuscle fibers) monitor muscle length by increasing/decreasing AP rateoGolgi Tendon Organs: Located at joining of tendon and muscle, detect tension in tendonoJoint Capsule Receptors:

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