Page 605 - Fundamentals of anatomy physiology

S p ot l i g h t592 Unit 3 Control and Regulation Figure 17–2

Olfaction and Gustation

Olfaction and gustation are special senses Stimulus
that give us vital information about our Dendrites
environment. Although the sensory
information is diverse and complex, each
special sense originates at receptor cells
that may be neurons or specialized
receptor cells that communicate with
sensory neurons.

OLFACTION Stimulus Specialized
Action removed olfactory
Olfactory receptors are the dendrites potentials neuron
of specialized neurons. When +30
dissolved chemicals contact the –70 mV
dendritic processes, there is a
depolarization, called a generator mV mV 0 Threshold
potential. This graph shows the
action potentials produced by a Stimulus
generator potential.
–60
–70 Generator potential

0 to CNS
Time (msec)

GUSTATION RECEPTOR CELL Stimulus
+30
The receptors for the senses of taste, vision,
equilibrium, and hearing are specialized 0 Stimulus
cells that have unexcitable membranes and Stimulus removed
form synapses with the processes of sensory
neurons. When stimulated, the membrane –60 Threshold –70 mV Receptor
of the receptor cell undergoes a graded –70 Depolarization –70 mV cell
depolarization that triggers the release of Synapse at
chemical transmitters at the synapse. These 0 dendrite
transmitters then depolarize the sensory Time (msec) Sensory
neuron, creating a generator potential and neuron
action potentials that are propagated to the
CNS. Because a synapse is involved, there is Stimulus AXON
a slight synaptic delay. However, this +30 Action
arrangement permits modification of the
sensitivity of the receptor cell by presynaptic Synaptic potentials
facilitation or inhibition. 0 delay
mV
592
–60 Generator potential to CNS
–70 Time (msec)

0