The olfactory epithelium is located within the nose. The epithelium contains olfactory
receptors, several supporting cells, and neurons of the olfactory nerves.
Structures of the olfactory epithelium • Figure 8.4
Sagittal view
Olfactory gland -
produces mucus.
Basal cell - a stem cell
that has undergone division
and differentiation to form a
new olfactory receptor.
Supporting cell - columnar v
epithelial cell that supports
receptor in the following ways:
• Physical support
• Nourishment
• Electrical insulation
• Detoxification of chemicals
that contact epithelium
Mucus secretion:
Olfactory bulb
Olfactory bulb
Parts of olfactory (I) nerve
Cribriform plate
Bundle of axons of
olfactory receptors
Connective tissue
Developing olfactory
- incomplete
receptor whose dendrite
has not reached mucus.
Olfactory receptor -
neuron that detects
odorants in its olfactory
hairs (cilia).
- chemicals
that stimulate the
olfactory hairs of
. ,
olfactory receptors.
• moistens epithelium
• dissolves/traps odorants
Enlarged aspect of olfactory receptors
Olfaction, like all the special senses, has a low thresh-
old. As little as a few molecules of certain substances can
be detected in the air. A good example is the chemical
methyl mercaptan, which smells like rotten cabbage and
can be detected in very low concentrations. Because nat-
ural gas is odorless, but a leak is potentially lethal, this
chemical is added in very small amounts to the natural gas
used for cooking and heating.
Some Special Senses Use Receptors That Detect Chemicals
previous page 268 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online next page 270 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online Home Toggle text on/off