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Chapter 16:Sensory, Motor,
and Integrative Systems
Copyright 2009, John Wiley & Sons, Inc.
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Sensation ,Perception & Integration
Sensationis the detection of stimulus of internal or external receptors. It
can be either conscious or subconcious
Components of sensation: Stimulation of the sensory receptor
transduction of the stimulus (energy-to-graded potential) generation of
nerve impulses integration of sensory input.
Perceptionis the awareness and conscious interpretation of sensations. It
is how the brain makes sense of or assigns meaning to the sensation.
We not aware of X-rays, ultra high frequency sound waves, UV light
- We have no sensory receptors for those stimuli
Integrationof sensory and motor functions occurs at many sites:
spinal cord brain stem cerebellum basal nuclei cerebral cortex Disruption of sensory, motor, or integrative structures or pathways can
cause disruptions in homeostasis
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Classification of Sensory Receptors
General senses: somatic and visceral.
Somatic- tactile, thermal, pain, pressure and proprioceptive sensations.
Visceral- provide information about conditions within internal organs.
- example: pH. Osmolarity, O2 and CO2 levels
Special senses- smell, taste, vision, hearing and equilibrium or balance.
Alternate Classifications of Sensory Receptors Structural classification
Type of response to a stimulus
Location of receptors & origin of stimuli
Type of stimuli they detect
Copyright 2009, John Wiley & Sons, Inc.
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Alternate Classifications of Sensory Receptors
Structural classification
Type of response to a stimulus
Location of receptors & origin of stimuli Type of stimuli they detect
Principles of Human Anatomy andPhysiology, 11e 4
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Structural Classification of Receptors
Free nerve endings
bare dendrites
pain, temperature, tickle, itch & light touch
Encapsulated nerve endings
dendrites enclosed in connective tissue capsule pressure, vibration & deep touch
Separate sensory cells
specialized cells that respond to stimuli
vision, taste, hearing, balance
Principles of Human Anatomy andPhysiology, 11e 5
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Copyright 2009, John Wiley & Sons, Inc.
Structural Classification of Rec
eptors
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skin, bones, internal organs, joints
Naked nerve endings surrounded
by one or more layers
Pacinian corpuscle
Free nerve endings
Encapsulated Nerve
EndingsvsUnencapsulated
Nerve Endings
Deeper tissue, muscles
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free nerve endings
root hair plexus
Meissnerscorpuscles
Paciniancorpuscles
Ruffini corpuscle
Merkel disc
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Classification by Stimuli Detected
Mechanoreceptors detect pressure or stretch
touch, pressure, vibration, hearing, proprioception,
equilibrium & blood pressure
Thermoreceptorsdetect temperature
Nociceptorsdetect damage to tissues (pain)
Photoreceptorsdetect light
Chemoreceptorsdetect molecules
taste, smell & changes in body fluid chemistry
Principles of Human Anatomy andPhysiology, 11e 9
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Classification by Location
Exteroceptors
near surface of body receive external stimuli
hearing, vision, smell, taste, touch, pressure, pain, vibration &temperature
Interoceptors
monitors internal environment (BV or viscera) not conscious except for pain or pressure
Proprioceptors
muscle, tendon, joint & internal ear
senses body position & movement
Principles of Human Anatomy andPhysiology, 11e 10
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Classification by Response to Stimuli Generator potential
free nerve endings, encapsulated nerve endings & olfactory receptorsproduce generator potentials
when large enough, it generates a nerve impulse in a first-order neuron
Receptor potential
vision, hearing, equilibrium and taste receptors produce receptorpotentials
receptor cells release neurotransmitter molecules on first-orderneurons producing postsynaptic potentials
PSP may trigger a nerve impulse
Amplitude of potentials vary with stimulus intensity
Principles of Human Anatomy andPhysiology, 11e 11
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Table 15.1 pt 1
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Table 15.1 pt 2
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Table 15.1 pt 3
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Adaptation of Sensory Receptors Most sensory receptors exhibit adaptationthe tendency for the generator
or receptor potential to decrease in amplitude during a maintained constant
stimulus.
Receptors may be rapidly or slowly adapting.
Rapidly adapting receptors: detect pressure, touch and smell.
- specialized for detecting changes
Slowly adapting receptors: detect pain, body position, and chemicalcomposition of the blood.
-nerve impulses continue as long as the stimulus persists
Pain is not easily ignored.
Change in sensitivity to long-lasting stimuli decrease in responsiveness of a
receptor
bad smells disappear
very hot water starts to feel only warm
potential amplitudes decrease during a maintained, constant stimulus
Copyright 2009, John Wiley & Sons, Inc.
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Somatic Sensations
Sensory receptors in the skin (cutaneous
sensations), muscles, tendons and joints and
in the inner ear.
Uneven distribution of receptors. (tongue,lips, fingertips)
Four modalities: tactile, thermal, pain and
proprioceptive.
Copyright 2009, John Wiley & Sons, Inc.
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Sensory Receptors in the Skin
Copyright 2009, John Wiley & Sons, Inc.
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Tactile Sensations
Include touch, pressure, vibration, itch and
tickle.
Tactile receptors in the skin are Meissner
corpuscles, hair root plexuses, Merkel discs,Ruffini corpuscles, pacinian corpuscles, and
free nerve endings.
Copyright 2009, John Wiley & Sons, Inc.
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Meissner Corpuscles or Corpuscles of
Touch Egg-shaped mass of dendrites enclosed by a
capsule of connective tissue.
Rapidly adapting receptors.
Found in the dermal papillae of hairless skin
such as in the fingertips, hands, eyelids, tip of
the tongue, lips, nipples, soles, clitoris, and
tip of the penis.
Copyright 2009, John Wiley & Sons, Inc.
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Hair Root Plexuses
Rapidly adapting touch receptors found in the
hairy skin.
Free nerve endings wrapped around hair
follicles.
Detect movements on the skin surface that
disturb hairs.
Copyright 2009, John Wiley & Sons, Inc.
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Merkel Discs or Tactile Discs
Also known as type I cutaneous
mechanoreceptors.
Slowly adapting touch receptors.
Saucer-shaped, flattened free nerve endings.
Found in the fingertips, hands, lips, and
external genitalia.
Copyright 2009, John Wiley & Sons, Inc.
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Ruffini Corpuscles
Also called as type II cutaneous
mechanoreceptors.
Elongated, encapsulated receptors.
Located deep in the dermis and in ligaments
and tendons.
Found in the hands, and soles.
Copyright 2009, John Wiley & Sons, Inc.
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Pacinian or Lamellated Corpuscles
Large oval structure composed of a
multilayered connective tissue capsule that
encloses a dendrite.
Fast adapting receptors.
Found around joints, tendons, and muscles;
in the periosteum, mammary glands, external
genitalia, pancreas and urinary bladder.
Copyright 2009, John Wiley & Sons, Inc.
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Thermal Sensations
Thermoreceptors are free nerve endings.
Two distinct thermal sensations:
cold receptors-
warm receptors-
Copyright 2009, John Wiley & Sons, Inc.
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Pain Sensations
Protective.
Sensory receptors are nociceptors .
Free nerve endings.
Two types of pain: fast and slow.
Fast pain: acute, sharp or pricking pain.
Slow pain: chronic, burning, aching or
throbbing pain.
Copyright 2009, John Wiley & Sons, Inc.
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Referred Pain
Pain is felt in or just deep to the skin that
overlies the stimulated organ or in a surface
area far from the stimulated organ.
Copyright 2009, John Wiley & Sons, Inc.
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Distribution of Referred Pain
Copyright 2009, John Wiley & Sons, Inc.
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Muscle Spindles
Interspersed among most skeletal muscle
fibers and aligned parallel to them.
Measure muscle stretching.
Consists of intrafusal muscle fibers-
specialized muscle fibers with sensory nerve
endings and motor neurons called gamma
motor neurons. Extrafusal muscle fibers- surrounding muscle
fibers supplied by alpha motor neurons.
Copyright 2009, John Wiley & Sons, Inc.
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A Muscle
Spindle and a
Tendon
Organ
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Tendon Organs
Located at the junction of a tendon and a
muscle.
Protect tendons and their associated muscles
from damage due to excessive tension.
Consists of a thin capsule of connective
tissue that encloses a few tendon fascicles.
Copyright 2009, John Wiley & Sons, Inc.
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Joint Kinesthetic Receptors
Found within or around the articular capsules
of synovial joints.
Free nerve endings and Ruffini corpuscles in
the capsules of joints respond to pressure.
Pacinian corpuscles respond to acceleration
and deceleration of joints during movement.
Copyright 2009 John Wiley & Sons Inc