special senses- 3 Flashcards
Chemical Senses
Taste and Smell
The receptors for taste and smell are
chemoreceptors, which generate neural signals on binding with particular chemicals in their environment
influence the flow of digestive juices and affect appetite.
The sensations of taste and smell in association with food intake
Taste receptor cells are located
primarily within tongue taste buds
Why do taste receptors have a life span of about 10 days
The taste receptor cells, by virtue of their task, frequently come into contact with potent chemicals.
Sensory inputs are conveyed via
the brain stem and thalamus to the primary gustatory (or taste) cortex.
We can discriminate among thousands of taste sensations, yet all tastes are varying combinations of five primary tastes:
Salty Sour Sweet Bitter Umami.
The olfactory (“smell”) mucosa in the ceiling of the nasal cavity contains three cell types:
Olfactory receptor cells
Supporting cells
Basal cells
What secretes mucus, which coats the nasal passages.
The supporting cells of the olfactory mucosa
precursors for new olfactory receptor cells
The basal cells
The sense of smell depends on
the olfactory receptor cells detecting odours, or scents.
olfactory receptor cell
an afferent neuron whose receptor portion lies in the olfactory mucosa and traverses into the brain.
form the olfactory nerve
The axons of the olfactory receptor cells collectively form the olfactory nerve.
consists of several long cilia that extend to the surface of the mucosa.
The receptor portion of an olfactory receptor cell
The receptor portion of an olfactory receptor cell consists of several long cilia that extend to the surface of the mucosa.
What do these cilia contain?
receptors for binding of odorants, molecules that can be smelled.
During quiet breathing
odorants typically reach the sensitive receptors only by diffusion
The act of sniffing enhances this process.
Odorants also reach the olfactory mucosa during eating by
wafting up to the nose from the mouth through the pharynx
To be smelled, a substance must be:
- Sufficiently volatile (easily vaporized) so
that some of its molecules can enter the
nose in the inspired air and - Sufficiently water soluble so that it can
dissolve in the mucus coating the olfactory
mucosa
Various parts of an odour are detected by different olfactory receptors and sorted into
smell files
Odour discrimination is coded by
patterns of activity in the olfactory bulb glomeruli.
