MCB 402Systems and Integrative Physiology• Nien-Pei Tsai, Ph.D.• Erik Nelson, Ph.D.http://www.life.illinois.edu/mcb/402/Neurophysiology• Lecture 1: Introduction, Overview of Nervous System, and Cellular Physiology• Lecture 2: Autonomic nervous system• Lecture 3: Somatosensory system• Lecture 4: Special senses I: Smell, Taste and Hearing • Lecture 5: Special senses II: Vision• Lecture 6: Motor system• Lecture 7: Higher functions of the nervous system• Lecture 8: Development and aging in neurophysiologySensory Modalities• General senses: Somatic senses (from the body)touch, pressure, vibration, itch, warm/cold, etc., Visceral senses (from the organs)pressure, pain, stretch, hunger, warm/cold, etc., Special senses: Smell, taste, vision, hearing.Olfaction: Sense of SmellCopyright © 2014 John Wiley & Sons, Inc.• There are 2 major parts of the olfactory system:1. Olfactory epithelium superior part of nasal cavity 3 types of cells2. Olfactory bulb Neurons (Mitral cells) project to higher center in the CNSOlfaction: Sense of SmellConstazo, Physiology 5thThere are 3 types of cells in olfactory epithelium:1. Olfactory receptor cells first-order neurons2. Supporting cellsepithelial cells to support the border and space3. Basal cells undifferentiated stem cells to produce receptor cellsOlfaction: Sense of SmellConstazo, Physiology 5thOlfaction: Sense of SmellCopyright © 2014 John Wiley & Sons, Inc.Olfactory PathwayOlfaction: Sense of SmellCopyright © 2014 John Wiley & Sons, Inc.Olfaction: Sense of SmellCopyright © 2014 John Wiley & Sons, Inc.• Olfactory transduction: binding of an odorant molecule to an olfactory receptor protein. • Chemical reactions involving cyclic AMP (cAMP) cause depolarization • Action potential travels to the primary olfactory area. • Impulse travels to the frontal lobe (orbitofrontal area) for odor identification.Gustation: Sense of TasteConstazo, Physiology 5thThere are 3 types of cells in a taste bud:1. Taste receptor cells2. Supporting cells3. Basal cellsGustation: Sense of Tastehttp://www.newtonsapple.org.uk/our-sense-of-taste/• Circumvallate papillae (about 12 that contain 100–300 taste buds)• Fungiform papillae (scattered over the tongue with about 5 taste buds each) • Foliate papillae (located in lateral trenches of the tongue—most of their taste buds degenerate in early childhood).Gustation: Sense of Tastehttp://www.newtonsapple.org.uk/our-sense-of-taste/• Filiform papillae cover the entire surface of the tongue. • Contain tactile receptors but no taste buds. • Increase friction to make it easier for the tongue to move food within the mouth.Gustation: Sense of TasteTaste buds on the tongue are organized in specialized papillae. Circumvallate papillae, Foliate papillae and Fungiform papillae.Constazo, Physiology 5thhttp://www.newtonsapple.org.uk/our-sense-of-taste/Constazo, Physiology 5thTaste buds on the tongue are organized in specialized papillae. Circumvallate papillae, Foliate papillae and Fungiform papillae.Constazo, Physiology 5thGustation: Sense of TasteXTaste buds on the tongue are organized in specialized papillae. Circumvallate papillae, Foliate papillae and Fungiform papillae.Gustation: Sense of Tastehttp://www.newtonsapple.org.uk/our-sense-of-taste/Gustation: Sense of TasteCopyright © 2014 John Wiley & Sons, Inc.• Three cranial nerves are involved the sense of taste.• Facial (VII) nerve carries taste information from the anterior 2/3 of the tongue. • Glossopharyngeal (IX)nerve carries taste information from the posterior 1/3 of the tongue. • Vagus (X) nerve carries taste information from taste buds on the epiglottis and in the throat.Hearinghttp://bio1152.nicerweb.com/Locked/media/ch50/ear.htmlHearing• The internal (inner) ear contains the cochlea which translates vibrations into neural impulses that the brain can interpret as sound, and the vestibular organ (vestibule and semicircular canals) that work with the cerebellum for balance and equilibrium.Copyright © 2014 John Wiley & Sons, Inc.HearingSound (Pressure) wavesOrgan of Corti vibratesThe tectorial membrane vibratesBending of cilia on hair cellsChange in K+ conductanceAction potentials in afferent cochlear nervesHearingCopyright © 2014 John Wiley & Sons, Inc.Cochlear nervesMedullamedial geniculate nucleusof the thalamusPrimary auditory cortexHearing and Equilibrium Equilibrium (balance) exists in two forms: Static equilibrium: maintenance of the body’s position relative to the force of gravity Dynamic equilibrium: the maintenance of the body’s position in response to sudden movements. Vestibular organs: The organs that maintain equilibrium. Includes saccule, utricle and semicircular canals. Copyright © 2014 John Wiley & Sons, Inc.• The otolithic membrane sits on top of the macula. Movement of the head causes gravity to move it down over hair cells. Hearing and Equilibrium• Three semicircular canals are responsible for equilibrium. • An ampulla in each canal contains the crista with a group of hair cells. Movement of the head affects the endolymph and hair cells. Hearing and EquilibriumHearing and EquilibriumSummary• Olfaction: olfactory epitheliumolfactory bud olfaction mechanism and pathway Gustation: taste bud (contains 3 types of papillae) gustation pathway Hearing: Cochlea 1. organ of Corti2. auditory transduction in hair cells and brain Vestibular organs saccule, utricle and semicircular
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