Gust & Olfac
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Transcript Gust & Olfac
Chemoreception – Olfaction and
Gustation
Olfactory organs
Olfaction
• Contain olfactory epithelium with olfactory
receptors, supporting cells, basal cells
– Olfactory receptors are modified neurons
• Surfaces are coated with secretions from
olfactory glands
• Olfactory reception involved detecting dissolved
chemicals as they interact with odorant binding
proteins
The Olfactory Organs
Olfaction
• Specialized neurons present in the
olfactory epithelium in the nose.
• They project cilia into a mucus
layer. The cilia are able to bind to
odorant molecules the binding
triggers an AP which is
transmitted to the olfactory area
of the olfactory bulb olfactory
cortex (lower frontal area and
limbic system of the brain
• Each olfactory receptor is
specialized for 1 odorant molecule
Olfaction
• Olfactory pathways
– No synapse in the thalamus for arriving information
• Olfactory discrimination
– Can distinguish thousands of chemical stimuli
• CNS interprets smells by pattern of receptor activity
– Olfactory receptor population shows considerable
turnover
– Number of receptors declines with age
Gustation
Taste receptors
• Clustered in taste buds
• Associated with lingual papillae
Taste buds
• Contain basal cells which appear to be stem cells
• Gustatory cells extend taste hairs through a
narrow taste pore
Gustatory Reception
Gustatory pathways
• Taste buds are monitored by cranial nerves
– Synapse within the solitary nucleus of the medulla
oblongata
– Then on to the thalamus and the primary sensory cortex
Gustatory discrimination
• Primary taste sensations
– Sweet, sour, salty, bitter
– Receptors also exist for umami and water
• Taste sensitivity shows significant individual
differences, some of which are inherited
• The number of taste buds declines with age
Taste
• Receptors for taste are
modified epithelial cell
present in taste buds
located on the tongue,
roof of the mouth and
pharynx
Taste receptors
Neural pathway
• Taste impulses travel through nerves VII, IX
and X to a gustatory nucleus in the medulla
oblongata (cross over) thalamus
gustatory cortex located in the parietal lobe in
the mouth area.
• What is the flavor of food?