Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dee Unglaub Silverthorn, Ph.D. H UMAN P HYSIOLOGY PowerPoint ® Lecture Slide Presentation by Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University AN INTEGRATED APPROACH T H I R D E D I T I O N Chapter 13 Integrative Physiology I: Control of Body Movement

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 S12-3 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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stimulus Sensory receptor Sensory (afferent) neuron CNS integration Efferent (motor) neuron Effector (target tissue) Response (movement) Feedback to CNS Neural Reflexes: Overview

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neural Reflexes: Overview Figure 13-1a: Monosynaptic and polysynaptic somatic motor reflexes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Effector Division Somatic Autonomic Integration site Spinal Brain Neurons in pathway Monosynaptic Polysynaptic Neural Reflexes: Classification of Pathways

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neural Reflexes: Classification of Pathways Figure 13-1: Monosynaptic and polysynaptic somatic motor reflexes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Regulate internal organs Integrate in spinal cord or lower brain Coordinate with hormones & pacemakers Autonomic Reflexes: “visceral reflexes”

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic Reflexes: “visceral reflexes” Figure 13-2: Autonomic reflexes

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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

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Muscle spindle In muscles Sense stretch Golgi tendon organ Near tendon Sense force Joint receptors Sense pressure Position Skeletal Muscle Reflex Sensory Receptors: Proprioceptors

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skeletal Muscle Reflex Sensory Receptors: Proprioceptors Figure 13-3: Sensory receptors in muscle

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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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Muscle tone Stretch reflex Muscle Spindles: Mechanism

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stretch Reflex and the Muscle Spindle Apparatus Figure 13-6b: Muscle reflexes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Golgi Tendon Reflex: Response to Excessive Force Force pulls collagen fibers which squeeze sensors Overload causes inhibition of contraction

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Myotactic unit: all pathways controlling a joint Example: elbow joint – all nerves, receptors, muscles A Myotactic Unit

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Tendon strike stretches quads- reflexive contraction Reciprocal (hamstring) muscle is inhibited Knee Jerk Reflex: Stretch & Reciprocal Inhibition Reflexes

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Knee Jerk Reflex: Stretch & Reciprocal Inhibition Reflexes Figure 13-7: The knee jerk reflex

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Pain stimulus Nocioceptors Spinal integration Flex appendage away Signal to brain (feel pain) Flexion Reflex: Pull away from Painful Stimuli

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Flexion Reflex: Pull away from Painful Stimuli Figure 13-8: Flexion reflex and the crossed extensor reflex

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Opposite leg Extensors stimulated Flexors inhibited Body supported Cross Extensor Reflex: To Keep Balance

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reflexive Movement Spinal integration Input to brain Postural reflexes Cerebellum integration Maintains balance Input to cortex Movement: Coordination of Several Muscle Groups Figure 13-9: Integration of muscle reflexes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cortex at top of several CNS integration sites Can be initiated with no external stimuli Parts can become involuntary: muscle memory Voluntary Movement: “Conscious”

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Voluntary Movement: “Conscious” Figure 13-11: Control of voluntary movements

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cortex initiation Central pattern generators In spine Maintain motion Combines movements Reflexive Voluntary Rhythmic Movements Figure 13-12: The corticospinal tract

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Anticipates body movement Reflexive adjustment to balance change Prepares body for threat: blink, duck, "tuck & roll" Combines with feedback Feed Forward: Postural Reflex Figure 13-13: Feedforward reflexes and feedback of information during movement

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Moves products in hollow organs Act as valves (sphincters): digestive tract or blood vessels Multiple controls: autonomic neurons, hormonal and paracrine Visceral Movement: Heart & Organs

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reflex pathways: spinal, cranial Sensor, afferent, integration, efferent, effector Classified by effector, integration site or synapses Summary

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 Summary