1 / 28

Chapter 10b

Chapter 10b. Sensory Physiology. Chemoreception: Smell and Taste. Olfaction is one of the oldest senses Taste is a combination of five basic sensations Taste transduction. Olfaction. Link between smell, memory, and emotion Vomeronasal organ (VNO) in rodents Response to sex pheromones

ama
Download Presentation

Chapter 10b

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 10b Sensory Physiology

  2. Chemoreception: Smell and Taste • Olfaction is one of the oldest senses • Taste is a combination of five basic sensations • Taste transduction

  3. Olfaction • Link between smell, memory, and emotion • Vomeronasal organ (VNO) in rodents • Response to sex pheromones • Olfactory cells • Olfactory epithelium in nasal cavity • Odorants bind to odorant receptors, G-protein-cAMP-linked membrane receptors

  4. Anatomy Summary: The Olfactory System Olfactorybulb Olfactorytract Olfactoryepithelium (a) The olfactory epithelium lies high within the nasalcavity, and its olfactory cells project to the olfactory bulb. Figure 10-14a

  5. Anatomy Summary: The Olfactory System Olfactory bulb Secondarysensory neurons Bone Primary sensoryneurons (olfactorycells) Olfactory epithelium (b) The olfactory cells synapse with secondarysensory neurons in the olfactory bulb. Figure 10-14b

  6. Anatomy Summary: The Olfactory System Olfactory receptor cellaxons (cranial nerve I)carry information toolfactory bulb. Lamina propria Basal cell layer includesstem cells that replaceolfactory receptor cells. Developingolfactory cell Olfactory cell(sensory neuron) Supporting cell Olfactory cilia(dendrites) containodorant receptors. Mucus layer:Odorant molecules mustdissolve in this layer. (c) Olfactory cells in the olfactory epithelium live only abouttwo months. They are replaced by new cells whose axonsmust find their way to the olfactory bulb. Figure 10-14c

  7. Olfactory Pathways Figure 10-15

  8. Taste Buds Figure 10-16a–b

  9. Taste Buds Sweet Umami Bitter Salty or sour Tight junction Support cell Presynapticcell ATP Serotonin Receptor cells Primary gustatoryneurons (c) Taste ligands create Ca2+ signals thatrelease serotonin or ATP. Figure 10-16c

  10. Summary of Taste Transduction Salt Sour Sweet, umami,or bitter ligand H+ Na+ 1 Gustducin 1 1 1 Ligands activate the taste cell. GPCR 2 2 2 2 Na+ Various intracellular pathwaysare activated. H+ Signaltransduction Celldepolarizes ? ? Ca2+ Ca2+ 3 3 3 Ca2+ signal in the cytoplasmtriggers exocytosis or ATPformation. Ca2+ Ca2+ 3 Ca2+ Ca2+ ? ATP Serotonin 4 4 Neurotransmitter or ATP isreleased. 4 4 Primary gustatoryneurons 5 Primary sensory neuron firesand action potentials aresent to the brain. 5 5 5 Figure 10-17

  11. Summary of Taste Transduction Salt Sour Sweet, umami,or bitter ligand H+ Na+ 1 Gustducin 1 1 1 Ligands activate the taste cell. GPCR 2 2 2 2 Na+ Various intracellular pathwaysare activated. H+ Signaltransduction Celldepolarizes ? ? Ca2+ Ca2+ 3 3 3 Ca2+ signal in the cytoplasmtriggers exocytosis or ATPformation. Ca2+ Ca2+ 3 Ca2+ Ca2+ ? ATP Serotonin 4 4 Neurotransmitter or ATP isreleased. 4 4 Primary gustatoryneurons 5 Primary sensory neuron firesand action potentials aresent to the brain. 5 5 5 Figure 10-17, steps 1–5

  12. Salt Sour Sweet, umami,or bitter ligand H+ Na+ 1 Gustducin 1 1 1 Ligands activate the taste cell. GPCR 2 2 2 2 Na+ Various intracellular pathwaysare activated. H+ Signaltransduction Celldepolarizes ? ? Ca2+ Ca2+ 3 3 3 Ca2+ signal in the cytoplasmtriggers exocytosis or ATPformation. Ca2+ Ca2+ 3 Ca2+ Ca2+ ? ATP Serotonin 4 4 Neurotransmitter or ATP isreleased. 4 4 Primary gustatoryneurons 5 Primary sensory neuron firesand action potentials aresent to the brain. 5 5 5 Summary of Taste Transduction • Humans and animals may develop specifichungersuch as salt appetite Figure 10-17

  13. The Ear: Hearing • Perception of sound • Sound transduction • The cochlea • Auditory pathways • Hearing loss

  14. Anatomy Summary: The Ear EXTERNAL EAR MIDDLE EAR INNER EAR The pinnadirects soundwaves intothe ear The oval window and the round window separatethe fluid-filled inner ear from the air-filled middle ear. Semicircularcanals Ovalwindow Malleus Incus Nerves Stapes Cochlea Vestibularappartus Earcanal Tympanicmembrane Roundwindow Topharynx Eustachiantube Internal jugularvein Figure 10-18

  15. Sound Waves • Hearing is our perception of energy carried by sound waves Figure 10-19a

  16. Sound Waves Figure 10-19b

  17. Sound Transmission Through the Ear 1 2 3 Sound waves strikethe tympanicmembrane andbecome vibrations. The sound waveenergy is transferredto the three bonesof the middle ear,which vibrate. The stapes is attached tothe membrane of the ovalwindow. Vibrations of theoval window create fluidwaves within the cochlea. Cochlear nerve Incus Ovalwindow Malleus Stapes Ear canal 5 Vestibular duct(perilymph) 3 Cochlear duct(endolymph) 2 6 4 Tympanic duct(perilymph) 1 Tympanicmembrane Roundwindow 4 5 6 Neurotransmitter releaseonto sensory neuronscreates action potentialsthat travel through thecochlear nerve tothe brain. Energy from the wavestransfers across thecochlear duct into thetympanic duct and isdissipated back intothe middle ear at theround window. The fluid waves push on theflexible membranes of thecochlear duct. Hair cells bendand ion channels open,creating an electrical signal thatalters neurotransmitter release. Figure 10-20, steps 1–6

  18. Anatomy Summary: The Cochlea Ovalwindow Cochlearduct Vestibularduct Organ ofCorti Saccule Cochlea Uncoiled Helicotrema Roundwindow Basilarmembrane Tympanicduct Bony cochlear wall Vestibular duct Cochlear duct Tectorial membrane Organ of Corti The movement of the tectorialmembrane moves the cilia onthe hair cells. Cochlear nerve transmitsaction potentials fromthe hair cells to theauditory cortex. Basilarmembrane Tympanicduct Fluid wave Cochlearduct Tectorialmembrane Haircell Tympanicduct Nerve fibers ofcochlear nerve Basilar membrane Figure 10-21

  19. Anatomy Summary: The Cochlea Ovalwindow Vestibularduct Cochlearduct Organ ofCorti Saccule Cochlea Uncoiled Helicotrema Roundwindow Tympanicduct Basilarmembrane Figure 10-21 (1 of 3)

  20. Anatomy Summary: The Cochlea • Perilymph in vestibular and tympanic duct • Similar to plasma • Endolymph in cochlear duct • Secreted by epithelial cells • Similar to intracellular fluid

  21. Anatomy Summary: The Cochlea Bony cochlear wall Vestibular duct Cochlear duct Tectorial membrane Organ of Corti Cochlear nerve transmitsaction potentials fromthe hair cells to theauditory cortex. Basilarmembrane Tympanicduct Figure 10-21 (2 of 3)

  22. Anatomy Summary: The Cochlea The movement of the tectorialmembrane moves the cilia onthe hair cells. Fluid wave Cochlearduct Tectorialmembrane Haircell Tympanicduct Nerve fibers ofcochlear nerve Basilar membrane Figure 10-21 (3 of 3)

  23. Signal Transduction in Hair Cells (a) At rest (b) Excitation (c) Inhibition Tip link Channels closed.Less cation entryhyperpolarizes cell. Somechannelsopen More channelsopen.Cation entrydepolarizescell. Stereocilium Hair cell Primarysensoryneuron Action potentials Action potentials increase No action potentials mV Action potentials inprimary sensory neuron Time 0 mV –30 Release Release Membrane potentialof hair cell Excitation opension channels Inhibition closesion channels Figure 10-22

  24. Sensory Coding for Pitch Figure 10-23a

  25. Sensory Coding for Pitch Figure 10-23b

  26. Auditory Pathways • Waves • Electrical signals in cochlea • Primary sensory neurons to brain in medulla oblongata • Sound projected to nuclei • Main pathway synapses in nuclei in midbrain and thalamus • Auditory cortex

  27. Anatomy Summary: The Cochlea Right auditory cortex Left auditory cortex Rightthalamus Leftthalamus Midbrain Pons Left cochlea Right cochlea Medulla Cochlear branch of rightvestibulocochlear nerve (VIII) Cochlear branch of leftvestibulocochlear nerve (VIII) Figure 10-24

  28. Hearing Loss • Conductive • No transmission through either external or middle ear • Central • Damage to neural pathway between ear and cerebral cortex or to cortex itself • Sensorineural • Damage to structures of inner ear

More Related