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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 13
Integrative Physiology I:
Control of Body Movement
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
About this Chapter
• Neural Reflexes: types & pathways
• Autonomic Reflexes pathways and functions
• Skeletal Muscle reflexes, myotactic units and
movement
• Combining reflexive and voluntary behavior into
locomotion
• Movement in visceral muscles
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Categories of skeletal muscle actions
• Categories Actions
• Extensor
Increases the angle at a joint
• Flexor
Decreases the angle at a joint
• Abductor Moves limb away from midline of body
• Adductor Moves limb toward midline of body
• Levator
Moves insertion upward
• Depressor Moves insertion downward
• Rotator
Rotates a bone along its axis
• Sphincter Constricts an opening
S12-3
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Neural Reflexes: Overview
• Stimulus
• Sensory receptor
• Sensory (afferent) neuron
• CNS integration
• Efferent (motor) neuron
• Effector (target tissue)
• Response (movement)
• Feedback to CNS
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Neural Reflexes: Overview
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Figure 13-1a: Monosynaptic and polysynaptic somatic motor reflexes
Neural Reflexes: Classification of Pathways
• Effector Division
• Somatic
• Autonomic
• Integration site
• Spinal
• Brain
• Neurons in pathway
• Monosynaptic
• Polysynaptic
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Neural Reflexes: Classification of Pathways
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 13-1: Monosynaptic and polysynaptic somatic motor reflexes
Autonomic Reflexes: “visceral reflexes”
• Regulate internal organs
• Integrate in spinal cord or lower brain
• Coordinate with hormones & pacemakers
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Autonomic Reflexes: “visceral reflexes”
Figure 13-2: Autonomic reflexes
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Examples of Autonomic Reflexes
• Cold Water Immersion causing tachycardia
• Pupillary Reflex-Pupil Constricting in response to light
• Baroreceptor Reflex- Low BP in carotid sinus results in tachycardia and
blood vessel constriction
• Carotid Sinus Reflex- Increased pressure within or external
manipulation of carotid sinus results in bradycardia
• Dilation of Blood vessels as body temperature increases
• Secretion of epinephrine and norepinephrine from the adrenal medulla
in response to fear or stress
• Sweating in response to increased body temperature
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Skeletal Muscle Reflex Sensory Receptors:
Proprioceptors
• Muscle spindle
• In muscles
• Sense stretch
• Golgi tendon organ
• Near tendon
• Sense force
• Joint receptors
• Sense pressure
• Position
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Skeletal Muscle Reflex Sensory Receptors:
Proprioceptors
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Figure 13-3: Sensory receptors in muscle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Alpha motoneuronsextrafusal fibers
bigger and more numerous than intrafusal
myofibrils all along length
this causes muscle contraction
Gamma motoneurons intrafusal fibers
tightens spindles
enhances sensitivity of spindles
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Upper motoneurons usually stimulate both
simultaneously ( Alpha-Gamma Coactivation)
Alpha motoneurons promote muscle contracting
Gamma motoneurons help maintain muscle tone
Reflexes are produced as an unconscious
response to particular stimuli
Can be simple or complex
Golgo tendon organs monitor tension
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Muscle Spindles: Mechanism
• Muscle tone
• Stretch reflex
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Stretch Reflex and the Muscle Spindle Apparatus
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Figure 13-6b: Muscle reflexes
Golgi Tendon Reflex: Response to Excessive Force
• Force pulls collagen fibers which squeeze sensors
• Overload causes inhibition of contraction
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Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
A Myotactic Unit
• Myotactic unit: all
pathways controlling a
joint
• Example: elbow joint –
all nerves, receptors,
muscles
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Knee Jerk Reflex:
Stretch & Reciprocal Inhibition Reflexes
• Tendon strike stretches quadsreflexive contraction
• Reciprocal (hamstring) muscle is inhibited
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Knee Jerk Reflex:
Stretch & Reciprocal Inhibition Reflexes
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Figure 13-7: The knee jerk reflex
Flexion Reflex: Pull away from Painful Stimuli
• Pain stimulus
• Nocioceptors
• Spinal integration
• Flex appendage away
• Signal to brain (feel pain)
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Double reciprocal innervation
stimulus on one side of the body, reaction
on another
Step on tack- affected foot withdraws (flexes),
Other foot extends to support weight
(crossed-extensor reflex)
Take-home lesson: some reflexes are simple;
affect and are controlled by a small part
of the spinal cord
Some are more elaborate
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Flexion Reflex: Pull away from Painful Stimuli
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Figure 13-8: Flexion reflex and the crossed extensor reflex
Cross Extensor Reflex: To Keep Balance
• Opposite leg
• Extensors stimulated
• Flexors inhibited
• Body supported
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Movement: Coordination of Several Muscle Groups
• Reflexive Movement
• Spinal integration
• Input to brain
• Postural reflexes
• Cerebellum
integration
• Maintains balance
• Input to cortex
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Figure 13-9: Integration of muscle reflexes
Voluntary Movement: “Conscious”
• Cortex at top of several CNS integration sites
• Can be initiated with no external stimuli
• Parts can become involuntary: muscle memory
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Voluntary Movement: “Conscious”
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Figure 13-11: Control of voluntary movements
Rhythmic Movements
• Cortex initiation
• Central pattern
generators
• In spine
• Maintain motion
• Combines
movements
• Reflexive
• Voluntary
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Figure 13-12: The corticospinal tract
Feed Forward: Postural Reflex
• Anticipates body movement
• Reflexive adjustment to balance change
• Prepares body for threat: blink, duck, "tuck &
roll"
• Combines
with
feedback
Figure 13-13: Feedforward reflexes and feedback of information during movement
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Visceral Movement: Heart & Organs
• Moves products in hollow organs
• Act as valves (sphincters): digestive tract or blood
vessels
• Multiple controls: autonomic neurons, hormonal
and paracrine
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Summary
• Reflex pathways: spinal, cranial
• Sensor, afferent, integration, efferent, effector
• Classified by effector, integration site or
synapses
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Summary
• Proprioceptor types, functions, role in reflexes &
balance
• Motor reflex pathways: stretch, Golgi tendon,
flexion, reciprocal inhibition & crossed extensor
• Myotatic unit structure and coordination
• Movement coordination: reflexive, voluntary,
rhythmic
• Feed forward and feedback coordination
• Visceral movement of body organs
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings