1. Types of Sensory Receptors
• Interoreceptors
receive stimuli from inside the body (pressure,osmo and chemoreceptors)
• Exteroreceptors
detect stimuli from outside(smell,hearing,Equilibrium)

2. • Chemoreceptors • Photoreceptors • Mechanoreceptor • Thermoreceptors
– Respond to chemical substance in the immediate vicinity
• Photoreceptors
– Respond to light energy (rods and cones)
• Mechanoreceptor
– Stimulated by mechanical force (detect changes in
fluid)
• Thermoreceptors
– In hypothallamus (cold and warm receptors)
• Pain receptors: nociceptors (naked dendrites that respond to chemicals released from damaged tissue)

3. Structure and Function of Sensory Receptors
• A sensory receptor is
a separate cell from the
afferent neuron
• The stimulus changes
the membrane potential
of the receptor cell,
which opens (or closes)
a calcium channel → ↑
or ↓ cytosolic [Ca]
• Changes in [Ca]
trigger (or inhibit) the
release of a chemical
transmitter by
exocytosis
• The transmitter
communicates to the
afferent neuron by
binding to receptros on
the afferent endings
• A sensory
receptor that
is a
specialized
ending of an
afferent
neuron
• The stimulus
acts on the
sensory
receptor by
opening or
closing ion
channel,
thereby
producing a
receptor
potential