the chemical senses: smell and tastemed.bpums.ac.ir/.../chemical_sense__0f28558b.pdf · smell and...
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The chemical senses: Smell and taste
chapter 53
Dr. Z Akbari
Sense of tastePrimary sensation of taste:
- 13 possible chemical receptor in taste cell13 possible chemical receptor in taste cell
Sour taste
S l Salty taste
Sweet taste
Bitter taste
Umami
Threshold for taste
Taste blindnessTaste blindness
Dr. Z Akbari
Function of Taste bud
L ti f t t b dLocation of taste bud :
Circumvallate papillae
Fungiform papillae
Foliate papillaeFoliate papillae
Specificity of taste buds
* Chemoreceptor cells live only * Chemoreceptor cells live only about about 10 10 daysdays
Dr. Z Akbari
Dr. Z Akbari
Mechanism of taste bud stimulation
Dr. Z Akbari
Mechanism of taste bud stimulation
Dr. Z Akbari
Dr. Z Akbari
Dr. Z Akbari
Transmission of
taste signals into
the CNS
Dr. Z Akbari
• Taste reflex integrated in the brain stem (sup & inf salivatory n)
• Adaptation of taste T f d i• Taste preference and aversion
Dr. Z Akbari
SmellOlf t bOlfactory membrane
Olfactory cells (Olfactory sensory neurons)Th lf iTh lf i f h i i lf h i i lThe olfactory mucosa contains The olfactory mucosa contains somatosensorysomatosensory receptors of the trigeminal receptors of the trigeminal nerve. Activation of these receptors with noxious or thermal stimuli. nerve. Activation of these receptors with noxious or thermal stimuli.
Dr. Z Akbari
Dr. Z Akbari
• Membrane potentials and AP in the olfactory cells• Mechanism of excitation of olfactory cells• Mechanism of excitation of olfactory cells• Adaptation: role of inhibitory granule cells
Th h ld f ll• Threshold for smell
Dr. Z Akbari
Olfactory Olfactory glumerolglumerol contains three main cell types:contains three main cell types:
mitral cells, tufted cells,mitral cells, tufted cells, and and interneuronsinterneurons (granule cells)(granule cells)
The olfactory glomeruli demonstrates lateral inhibition mediated byThe olfactory glomeruli demonstrates lateral inhibition mediated byThe olfactory glomeruli demonstrates lateral inhibition mediated by The olfactory glomeruli demonstrates lateral inhibition mediated by periglomerular cells and granule cells. This sharpens and focuses olfactory periglomerular cells and granule cells. This sharpens and focuses olfactory signalssignals
Dr. Z Akbari
Central olfactory pathwaysCentral olfactory pathwaysTh f i l ll lf• The axons of mitral cells olfactory tracts.
• Anterior olfactory nucleus (Within the olfactory tracts) receivesinput from and projects to the contralateral olfactory bulb through thep p j y ganterior commissure.
• At the base of the brain, OT splits into the lateral and medialolfactory striaeolfactory striae.
• Lateral olfactory stria primary olfactory cortex(prepiriformcortex.
• Medial olfactory stria amygdala Basal forebrainLimbic system
Dr. Z Akbari
Neo cortex: Conscious discrimination of odors.Neo cortex: Conscious discrimination of odors.Limbic projection: Affective nature of smellOdors can effectively call up memoriesOdors can effectively call up memories
The endThe end
Odors can effectively call up memories. Odors can effectively call up memories. Dr. Z Akbari
Most people walk in and Most people walk in and out of your life,out of your life,butbutonly friends leave only friends leave yyfootprints in your heart.footprints in your heart.
Dr. Z Akbari
Neo cortex: Conscious discrimination of odorsNeo cortex: Conscious discrimination of odors
Limbic projection (amygdala & hypothalamus): Affective nature of smellDr. Z Akbari
Dr. Z Akbari