Chapter 10b Sensory Physiology 2013 Pearson Education Inc Figure 10 13a b ANATOMY SUMMARY The Olfactory System Olfactory Pathways The olfactory epithelium lies high within the nasal cavity and its olfactory neurons project to the olfactory bulb Sensory input at the receptors is carried through the olfactory cortex to the cerebral cortex and the limbic system Cerebral cortex Limbic system Olfactory bulb Olfactory tract Olfactory cortex Cranial Nerve I Olfactory neurons in olfactory epithelium Figure 10 13b ANATOMY SUMMARY The Olfactory System The olfactory neurons synapse with secondary sensory neurons in the olfactory bulb Olfactory bulb Secondary sensory neurons Olfactory sensory neurons Bone Olfactory epithelium FIGURE QUESTION Multiple primary neurons in the epithelium synapse on one secondary neuron in the olfactory bulb This pattern is an example of what principle Figure 10 13c ANATOMY SUMMARY The Olfactory System Olfactory neurons in the olfactory epithelium live only about two months They are replaced by new neurons whose axons must find their way to the olfactory bulb Olfactory neuron axons cranial nerve I carry information to olfactory bulb Lamina propria Basal cell layer includes stem cells that replace olfactory neurons Developing olfactory neuron Olfactory sensory neuron Supporting cell Olfactory cilia dendrites contain odorant receptors Mucous layer Odorant molecules must dissolve in this layer Olfaction Link between smell memory and emotion Vomeronasal organ VNO in rodents Response to sex pheromones Olfactory sensory neurons Olfactory epithelium in nasal cavity Odorants bind to odorant receptors G protein linked membrane receptors 2013 Pearson Education Inc Gustation Closely linked to olfaction Taste is a combination of five basic sensations sweet sour salty bitter umami Taste cells are non neural epithelium Each taste cell is sensitive to only one taste Taste transduction Gustducin Humans and animals may develop specific hunger such as salt appetite 2013 Pearson Education Inc Figure 10 14a ESSENTIALS Taste Figure 10 14a ESSENTIALS Taste Taste buds Each taste bud is composed of taste cells joined near the apical surface with tight junctions Sweet Umami Bitter Sour Tight junction Type I support cells may sense salt when Na enters through Na channels Salt Adapted from Tomchik et al J Neurosci 27 40 10840 10848 2007 Presynaptic cell III ATP Serotonin Primary sensory neurons Receptor cells type II Figure 10 14b ESSENTIALS Taste Taste transduction Each taste cell senses only one type of ligand Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Sour H H Ca2 Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell Various intracellular pathways are activated Ca2 signal in the cytoplasm triggers exocytosis or ATP formation Neurotransmitter or ATP is released Primary sensory neuron fires and action potentials are sent to the brain Ca2 Ca2 Ca2 ATP Primary gustatory neurons Figure 10 14b ESSENTIALS Taste Slide 1 Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Ca2 Ca2 Ca2 Sour H H Ca2 Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell ATP Primary gustatory neurons 2013 Pearson Education Inc Figure 10 14b ESSENTIALS Taste Slide 2 Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Ca2 Ca2 Ca2 Sour H H Ca2 Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell Various intracellular pathways are activated ATP Primary gustatory neurons 2013 Pearson Education Inc Figure 10 14b ESSENTIALS Taste Slide 3 Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Ca2 Ca2 Ca2 Sour H H Ca2 Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell Various intracellular pathways are activated Ca2 signal in the cytoplasm triggers exocytosis or ATP formation ATP Primary gustatory neurons 2013 Pearson Education Inc Figure 10 14b ESSENTIALS Taste Slide 4 Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Ca2 Ca2 Ca2 Sour H H Ca2 ATP Primary gustatory neurons 2013 Pearson Education Inc Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell Various intracellular pathways are activated Ca2 signal in the cytoplasm triggers exocytosis or ATP formation Neurotransmitter or ATP is released Figure 10 14b ESSENTIALS Taste Slide 5 Gustducin Sweet umami or bitter ligand GPCR Receptor cells with G protein coupled membrane receptors bind either bitter sweet or umami ligands and release ATP as a signal molecule Signal transduction Ca2 Ca2 Ca2 Sour H H Ca2 ATP Primary gustatory neurons 2013 Pearson Education Inc Presynaptic cells sense sour taste H but it is not clear whether H acts on a receptor or enters the cell Ligands activate the taste cell Various intracellular pathways are activated Ca2 signal in the cytoplasm triggers exocytosis or ATP formation Neurotransmitter or ATP is released Primary sensory neuron fires and action potentials are sent to the brain Figure 10 15 ANATOMY SUMMARY The Ear The Ear Hearing Perception of energy carried by sound waves Frequency is translated into pitch Loudness is an interpretation of intensity a function of wave amplitude 2013 Pearson Education Inc Figure 10 16a 1 of 2 Sound waves alternate peaks of compressed air and valleys where the air is less compressed Wavelength Tuning fork Figure 10 16b 2 of 2 Sound waves are distinguished by their amplitude measured in decibels dB and frequency measured in hertz Hz 1 Wavelength Intensity dB Amplitude