Transcript Types of Receptors

5 Types of Receptors
• 1) Chemoreceptor – responsive to
changes in chemical concentrations
• 2) Pain Receptor – responsive to
chemicals released during tissue damage
• 3) Thermoreceptors – responsive to
changes in temperature
• 4) Mechanoreceptors – responsive to
changes in pressure and fluid movement
• 5) Photoreceptors – respond to light
energy
• Sensations – feeling that occurs when
sensory impulses are interpreted by the
brain. Different sensations depend on the
region of the brain that interprets the
impulse
• Sensory Projection – The brain causes the
feeling to come from the receptors being
stimulated
• Sensory Adaptation – receptors adapt by
failing to send impulses under constant
stimulation. Stimulus must increase in
order for more impulses to be sent.
Somatic Senses
• Senses associated with the skin, muscles
joints and visceral organs.
• Touch and pressure employ 3 kinds of
receptors
• 1) Free nerve endings in between
epithelial cells
• 2) Meissner’s Corpuscles – most common
in hairless portions of the skin. Most
responsive to light touch.
• 3) Pacinian’s Corpuscles – Found in the
subcutaneous layers of the skin, tendons
and ligaments. Responsive to pressure.
Temperature Receptors
• Free nerve endings. Are responsive to heat or
cold.
• Heat receptors are most responsive to
temperatures between 77o F and 113o F.
• Cold Receptors are most responsive to
temperatures between 50o F and 68o F.
• Above 113o F and below 50o F pain receptors
cause a freezing or burning sensation.
• Both heat and cold receptors adapt very rapidly.
Pain Receptors
• Free nerve endings. Found everywhere
except the nerve tissue of the brain.
• Stimulated by tissue damage
• Pain receptors adapt very poorly. The
send impulses under constant stimulation.
• Pain receptors are the only receptors in
visceral organs
• Referred Pain – The brain makes you feel
as though pains in the abdomen originate
in another part of the body.
Sense of Smell
• Olfactory receptor cells are Chemoreceptors
located on the roof of the nasal cavity
• They are neurons with tiny knobs at their
ends covered with cilia
• Chemicals that stimulate these cells enter as
gases. They must partially dissolve in the
fluid surrounding the cells to be detected
• Olfactory cells undergo adaptation rapidly for
a particular odor
Sense of Taste
• The special organs of taste are chemoreceptors
called Taste Buds
• Taste buds occur in association with tiny
elevations on the tongue called Papillae
• Each taste bud consists of many taste cells
(Gustatory Cells)
• Each gustatory cell has hairs which are the
sensitive parts of the cell
• Taste receptors adapt rapidly for a particular
taste
• Chemicals are detected only when dissolved in
Saliva.
• There a 4 varieties of taste cells each most
sensitive to a particular taste
• 1) Sweet Receptors – most concentrated on
the tip of the tongue
• 2) Sour Receptors – most concentrated on
the sides of the tongue
• 3) Salty Receptors – also most concentrated
on the tip of the tongue
• 4) Bitter Receptors – most concentrated on
the back of the tongue