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Chapter 13 Integrative Physiology I: Control of Body Movement.

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Presentation on theme: "Chapter 13 Integrative Physiology I: Control of Body Movement."— Presentation transcript:

1 Chapter 13 Integrative Physiology I: Control of Body Movement

2 About this Chapter Neural reflexes Autonomic reflexes Skeletal muscle reflexes The integrated control of body movement Control of movement in visceral muscles

3 Neural Reflexes Table 13-1

4 Somatic Motor Reflexes Monosynaptic and polysynaptic somatic motor reflexes Figure 13-1a Stimulus Sensory neuron Receptor Efferent neuron Target cell effector Response (a) A monosynaptic reflex has a single synapse between the afferent and efferent neurons. Spinal cord Integrating center One synapse Somatic motor neuron Skeletal muscle

5 Somatic Motor Reflexes Figure 13-1b Response Stimulus Sensory neuron Efferent neuron Interneuron (b) Polysynaptic reflexes have two or more synapses. Target cell effector Spinal cord Integrating center Receptor Synapse 1 Synapse 2

6 Postganglionic autonomic neuron Preganglionic autonomic neuron CNS integrating center Sensory neuron Receptor Stimulus Response Target cell Autonomic ganglion Autonomic Reflexes Some visceral reflexes are spinal reflexes no brain involvement, or brain modulated “bashful bladder” / toilet training / goose pimples Figure 13-2

7 Skeletal Muscle Reflexes Proprioceptors are located in skeletal muscle, joint capsules, and ligaments Proprioceptors carry input sensory neurons to CNS CNS integrates input signal Somatic motor neurons carry output signal Alpha motor neurons α Effectors are contractile skeletal muscle fibers extrafusal muscle fibers

8 Proprioceptors Muscle spindle Response to stretch Within muscle fibers as intrafusal fibrer Automonic with gamma motor neurons Golgi tendon organ Muscle tension especially during isometric Relaxation reflex - protective Joint receptors Are found in capsules and ligaments around joints

9 Proprioceptors Muscle spindles and Golgi tendon organs are sensory receptors in muscle Figure 13-3a Muscle spindle Extrafusal muscle fibers Tendon Alpha motor neuron Golgi tendon organ (a)

10 Proprioceptors Figure 13-3b Muscle spindle Extrafusal fiber Intrafusal fibers Central region lacks myofibrils. Gamma motor neurons Tonically active sensory neurons Gamma motor neurons from CNS (b) Muscle spindle To CNS Spindle fibers: Sense stretch

11 Proprioceptors Figure 13-3c (c) Golgi tendon organ Extrafusal muscle fibers Sensory neuron Collagen fiber Capsule Tendon Afferent neuron

12 Muscle Spindles Muscle spindles monitor muscle length and prevent overstretching Figure 13-4a Sensory neuron endings Intrafusal fibers of muscle spindle (a) Spindles are firing even when muscle is relaxed. Spinal cord Sensory neuron Alpha motor neuron Extrafusal muscle fibers at resting length Sensory neuron is tonically active. Spinal cord integrates function. Alpha motor neurons to extrafusal fibers receive tonic input from muscle spindles. Extrafusal fibers maintain a certain level of tension even at rest

13 Muscle Spindles Figure 13-4b

14 Alpha-Gamma Coactivation Figure 13-5a (a) Alpha-gamma coactivation Muscle length Muscle shortens Intrafusal fibers do not slacken so firing rate remains constant. Muscle shortens Action potentials of spindle sensory neuron Time Alpha motor neuron fires and gamma motor neuron fires. Muscle contracts. Stretch on centers of intrafusal fibers unchanged. Firing rate of afferent neuron remains constant

15 Without Gamma Motor Neurons Figure 13-5b (b) Muscle shortens Action potential Muscle shortens Time Alpha motor neuron fires. Less stretch on center of intrafusal fibers Firing rate of spindle sensory neuron decreases. Muscle contracts. Less stretch on intrafusal fibers Muscle length Action potentials of spindle sensory neuron

16 Muscle Reflexes Help Prevent Damage Figure 13-6a Sensory neuron Spindle Spinal cord Motor neuron Add load Muscle (a) Load added to muscle. Muscle spindle reflex

17 Muscle Reflexes Help Prevent Damage Figure 13-6b

18 GTO’s Figure 13-7

19 Movement Types of movement Reflex Voluntary Rhythmic

20 CNS Integrates Movement Spinal cord integrates spinal reflexes and contains central pattern generators Brain stem and cerebellum control postural reflexes and hand and eye movements Cerebral cortex and basal ganglia Voluntary movement

21 CNS Integrates Movement Table 13-3

22 CNS Control of Voluntary Movement Figure 13-10

23 CNS Control of Voluntary Movement Feedforward reflexes and feedback of information during movement Figure 13-13

24 Parkinson’s Disease Progressive neural disorder Characterized by abnormal movements, speech difficulties, and cognitive changes Loss of basal ganglia that release dopamine

25 Visceral Movement Moves products in hollow organs Controlled by ANS Some create own action potentials

26 Summary Neural reflexes Somatic reflexes, autonomic reflexes, spinal reflexes, cranial reflexes, monosynaptic reflex, and polysynaptic reflex Autonomic reflexes Skeletal muscle reflexes Extrafusal muscle fibers, alpha motor neurons, muscle spindles, intrafusal fibers, gamma motor neurons, muscle tone, and stretch reflex

27 Summary Skeletal muscle reflexes (continued) Alpha-gamma coactivation, golgi tendon organs, myotatic unit, reciprocal inhibitions, flexion reflexes, crossed extensor reflex, and central pattern generator Integrated control Reflex movement, postural reflexes, voluntary movement, rhythmic movements, corticospinal tract, basal ganglia, and feedforward reflexes Control of movement in visceral muscles


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