chapter 17
Chapter 17: The Special Senses
I. An Introduction to the Special Senses
The state of our nervous systems determines what we perceive.
1. For example, during sympathetic activation, we experience a heightened awareness of sensory information and hear sounds that would normally escape our notice.
2. Yet, when concentrating on a difficult problem, we may remain unaware of relatively loud noises.
The five special senses are: olfaction, gustation, vision, equilibrium, and hearing.
II. Olfaction
The olfactory organs are located in the nasal cavity on either side of the nasal septum.
The olfactory organs are made up of two layers: the olfactory epithelium and the lamina propria.
The olfactory epithelium contains the olfactory receptors, supporting cells, and basal (stem) cells.
The surfaces of the olfactory organs are coated with the secretions of the olfactory glands.
Olfactory Receptor
The olfactory receptors are highly modified neurons.
Olfactory reception involves detecting dissolved chemicals as they interact with odorant-binding proteins.
Olfactory Pathways
Axons leaving the olfactory epithelium collect into 20 or more bundles that penetrate the cribriform plate of the ethmoid bone to reach the olfactory bulbs of the cerebrum where the first synapse occurs.
Axons leaving the olfactory bulb travel along the olfactory tract to reach the olfactory cortex, the hypothalamus, and portions of the limbic system.
In olfaction, the arriving information reaches the information centers without first synapsing in the thalamus.
Olfactory Discrimination
The olfactory system can distinguish thousands of chemical stimuli. The CNS interprets smells by the pattern of receptor activity.
Aging and Olfactory Sensitivity
The olfactory receptor population shows considerable turnover. The number of olfactory receptors declines with age.
III. Gustation
Taste (gustatory) receptors are clustered in taste buds.
Taste
I. An Introduction to the Special Senses
The state of our nervous systems determines what we perceive.
1. For example, during sympathetic activation, we experience a heightened awareness of sensory information and hear sounds that would normally escape our notice.
2. Yet, when concentrating on a difficult problem, we may remain unaware of relatively loud noises.
The five special senses are: olfaction, gustation, vision, equilibrium, and hearing.
II. Olfaction
The olfactory organs are located in the nasal cavity on either side of the nasal septum.
The olfactory organs are made up of two layers: the olfactory epithelium and the lamina propria.
The olfactory epithelium contains the olfactory receptors, supporting cells, and basal (stem) cells.
The surfaces of the olfactory organs are coated with the secretions of the olfactory glands.
Olfactory Receptor
The olfactory receptors are highly modified neurons.
Olfactory reception involves detecting dissolved chemicals as they interact with odorant-binding proteins.
Olfactory Pathways
Axons leaving the olfactory epithelium collect into 20 or more bundles that penetrate the cribriform plate of the ethmoid bone to reach the olfactory bulbs of the cerebrum where the first synapse occurs.
Axons leaving the olfactory bulb travel along the olfactory tract to reach the olfactory cortex, the hypothalamus, and portions of the limbic system.
In olfaction, the arriving information reaches the information centers without first synapsing in the thalamus.
Olfactory Discrimination
The olfactory system can distinguish thousands of chemical stimuli. The CNS interprets smells by the pattern of receptor activity.
Aging and Olfactory Sensitivity
The olfactory receptor population shows considerable turnover. The number of olfactory receptors declines with age.
III. Gustation
Taste (gustatory) receptors are clustered in taste buds.
Taste