Ch 18 Nervous System 18 03 2010 18 23 00 Receptor specialized cells or process that monitors conditions in the body or in the external environment Sense Mostly found in skin and scattered throughout the body Special Senses Located in the specialized oranges o Olfaction o Gustation tastes o Equilibrium balance o Hearing o Vision Sensory receptor o Specialized cell that sends Receptor and Receptive fields One area or field receptor by one cell Simple classification of receptors Exteroceptors tell the CNS about external environment Proprioceptors tell the CNS about body position muscle joints Interoceptors tell the CNS about the internal environment monitor conditions inside the body General sense receptors Nociceptors pain o Respond to stimuli associated with tissue damage o Two types Fast prickling pain Slow burning and aching pain o Free nerve endings Thermoreceptors o Respond to changes in temperature o Conduct sensations along same pathway as nociceptors o Free nerve endings Mechanoreceptor o Respond to physical distortion contact or pressure o Three types Tactile receptor Touch pressure vibration Baroreceptor Pressure changes in walla of vessels tracts Proprioreceptors Position of joints and muscles Chemoreceptors Types of receptor in the skin Respond to specific stimulus In the dermis Free nerve ending pain simplest type of receptors Tactile disc fine touch and pressure Root hair plexus free nerve endings Referred Pain Pain sensations originating in visceral organs o Often perceived as involving specific regions of the body surface Heart is in chest goes down left arm Don t understand why Appendix is in middle of abdomen Mechanoreceptor Baroreceptor stretch receptor Olfactory Receptors Olfactory epithlium contains receptors o Lateral wall of nasal cavity o Nasal septum Olfactory nerve 1st cranial nerve Neurons sensitive to chemicals which dissolve in mucus Also present o Supporting cells o Basal cells stem cells Covered in secretions of olfactory glands Olfactory cells o Replaced by new cells from basal cells Olfactory cells are the only receptors replaces on on going basis Gustation Discrimination Sensations o Sweet o Sour o Salty o Butter o Umami pleasant taste like chicken broth o Water Individual differences in sensitity Goes along with smell Travel o Facial nerve 7th o Glossopharyngeal nerve 9th o Vagus nerve 10th Hearing and Balance Deep in temporal bone Auricle gathers sound waves and pushes the waves down external acoustic canal meatus Middle ear o ossicles Malleus attached to the tympanic membrane Incus Stapes Inner ear o Senses of equilibrium and hearing are found in inner ear o Receptors are within the fluid filled tubes and canals chambers membranous labyrinth endolymph o Membranous labyrinth is surrounded by bone and is a system of tubes and has a fluid within it endolymph o Middle portion Vestibule space with two membranous sacs and the utricle and saccule macula receptor sensations of gravity and linear acceleration o posterior portion semicircular ducts lie in canal system of boney labyrinth crista ampullaris receptor sensation of angular movement Cochlea Seashell looking Organ of corti receptor for hair Supporting cells on basalar membrane Tectorial membrane Pressure passes through vestibular duct and tympanic duct Pressure in perilymph and tympanic duct distorts Macula Receptor for linear acceleration o Found in utrible and saccule of membranous labyrinth Hair cells within maculae Cilia cntact otoliths statoconis in gelatinous matrix Tilting head shifts otoliths which distorts hair cells causing them to fire off to 8th nerve to brain Semicircular canals Anterior duct for yes motion Lateral duct for no motion Posterior duct for tilting head Crista ampullaris Receptor for angular movement Endolymph movement o Cilia contact gelatinous cupula of crista ampullaris o Causes hairs to fire off Eye and vision Levator palepebrae superioris muscle opens the eye Tarsal plate has fliud in front of eye in eyelid Conjunctiva Mucous membrane that covers o Inner surface of eyelids Palpebral conjuctiva o Surface of the eye Ocular conjunctiva Does not cover the cornea Cavities of the eyeball Anterior cavity or chamber o Contains aqueous humor Posterior cavity or vitreous chamber o Contains vitreous humor Walls Outer fibrous o Sclera white o Cornea transparent o Provides mechanical support attachment of extra ocular eye muscles Middle laye o Iris o Cilliary body o Bhronoid Inner layer 18 03 2010 18 23 00 18 03 2010 18 23 00
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