PHED-2506EL Chapter Notes - Chapter 13: Pattern Recognition, Cerebral Cortex, Dermis
25 Jun 2018
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Lecture 13A:
What are SENSORY RECPETORS? —specialized structures that
respond to various stimuli within the environment. The
activation of these receptors result in graded potentials that
trigger nerve impulses along the PNS, resulting in
depolarizations that trigger impulses to the central nervous
system. The registration of these stimuli occur in the brain.
oSENSATION = awareness of the stimulus
oPERCEPTION = interpretation of the meaning of the
stimulus
List and describe the 5 types of receptors by stimulus.
1. Mechanoreceptors: respond to touch, pressure, vibration,
stretch, and itch
2. Thermoreceptors: sensitive to changes in temperature
3. Photoreceptors: respond to light energy
4. Chemoreceptors: respond to chemicals
oThere are many different chemoreceptors—each of which
respond to different chemicals.
5. Nociceptors: sensitive to pain-causing stimuli
oSearing heat, extreme cold, excessive pressure, and
inflammatory chemicals are interpreted as painful.
EXAMPLE: If you were to lick on ice cream cone, you would be
stimulating both thermo- and chemoreceptors.
List and describe the 3 types of receptors by location.
1. Exteroceptors:
Respond to stimuli outside of the body
Found near the surface of the body
Sensitive to touch, pressure, pain, and temperature
Include receptors of special senses: vision, hearing,
equilibrium, taste, smell)
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2. Interoceptors:
aka visceroceptors
Respond to stimuli within the body
Found in internal viscera and blood vessels
Sensitive to chemical changes, stretch, and
temperature changes
Sometimes their activity causes us to feel pain,
discomfort, hunger, or thirst (fairly rare)
3. Proprioceptors:
Respond to internal stimuli (however, their location
is restricted)
Respond to degree of stretch of the organs they occupy
Found in skeletal muscles, tendons, joints, ligaments,
and connective tissue coverings of bones and muscles
Constantly “advise” the brain of the body’s movements
by monitoring how much the organs containing these
receptors are stretched.
Contrast using examples, free nerves with encapsulated nerves.
Non-encapsulated (FREE) Nerve
Endings (p. 485)
Most of these sensory fibres
are nonmyelinated.
Encapsulated Nerve Endings
Consist of one or more fiber
terminals of sensory neurons
enclosed in a connective
tissue capsule. Most are
mechanoreceptors that vary
greatly in shape, size, and
distribution.
abundant in epithelia +
connective tissue
free dendritic nerve endings
(primarily respond to temp.
and pain)
Meissner’s corpuscles
(tactile): surrounded by
Schwann cells + egg-shaped
connective tissues. Found just
beneath epidermis.
Purpose: discriminative
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Specialized structures that respond to various stimuli within the environment. The activation of these receptors result in graded potentials that trigger nerve impulses along the pns, resulting in depolarizations that trigger impulses to the central nervous system. The registration of these stimuli occur in the brain: sensation = awareness of the stimulus, perception = interpretation of the meaning of the stimulus. Example: if you were to lick on ice cream cone, you would be stimulating both thermo- and chemoreceptors. List and describe the 3 types of receptors by location: exteroceptors: Respond to stimuli outside of the body. Found near the surface of the body. Sensitive to touch, pressure, pain, and temperature. Include receptors of special senses: vision, hearing, equilibrium, taste, smell: interoceptors: Found in internal viscera and blood vessels. Sensitive to chemical changes, stretch, and temperature changes. Sometimes their activity causes us to feel pain, discomfort, hunger, or thirst (fairly rare: proprioceptors:
