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UCONN - PNB 2264 - Class Notes - Week 10

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UCONN - PNB 2264 - Class Notes - Week 10

School: University of Connecticut
Department: Physiology
Course: Human Physiology and Anatomy
Professor: Kristen Kimball
Term: Fall 2018
Tags:
Name: PNB 2264 week 10
Description: These notes cover class power-points and objectives.
Uploaded: 11/09/2018
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background image Learning Objectives: Motor Control (Ch. 14) 1. List components of the motor control hierarchy Higher Centers ­decision making ­structures include supplementary motor area,  motor  association cortex Middle Level 
(Coordinator)
­convert command; may specify individual postures and 
movements
­structures include M1 (primary motor cortex), basal ganglia 
(nuclei), Thalamus, Brainstem, cerebellum 
Local Level 
(Operator)
­specify regional movement
­structures: levels of brainstem; spinal cord
2. Define three classes of movement Reflex Flexor Withdrawal      ­cannot stop the reflex, but you can dampen it
     ­ex. Reflex hammer
Rhythmic Stereotypic: same pattern over and over again Central Pattern Generators in the Spinal Cord o Spindle core is “hard­wired for RHYTHMIC stereotyped 
movements
Sindle cat can walk on treadmill Spinal dog has scratch flex Neonate stepping reflex ex.) walking, running, bouncing (kangaroo), swimming Voluntar
y
Coordinated movement ex.) Touching finger to the nose, pitching, writing, eating 3. Describe sensory and motor innervation of skeletal muscle Extrafusal­ muscle does the work Intrafusal­ muscle modified into sensory receptor Innervation of skeletal muscle   Motor 
innervation:
Alpha motor neurons (innervates extrafusal muscle) Gamma motor neurons (innervates intrafusal muscle)
background image o Pulls on the muscle spindle (to stretch) o Contracts the striated ends so the middle muscle fiber 
sensory region would be stretched
Sensory 
innervation:
Afferents from proprioceptors (intrafusal) o Wired to muscle spindles  Receptor 
innervation:
Muscle spindles= “intrafusal muscle” o Ends are striated(innervated with Gamma motor  neurons)  o Nuclear bag fibers o Nuclear chain fibers Golgi tendon organs o proprioceptive sensory receptor organ that 
senses changes in muscle tension
o are activated by stretch or active contraction of a  muscle and that transmit information about 
muscle tension. Activation of these receptors 
results in a reflex inhibition of the muscle via the 
inverse myotatic reflex.
Without Gamma intervention  Stretch normal  But when contracting­ spindles shorten too, firing rate goes down, kind of 
lose proprioceptive input, wouldn't know position in space
Alpha­Gamma Coactivation When firing alpha motor neurons, gamma motor neurons are co­activated o Contractile ends of spindle to shorten, which o “Biases” muscle spindle, keeping it responsive at all lengths    Intrafusal muscle fibers  A. are sensory receptors, 
B. are innervated by afferent (sensory) neurons, 
C. are innervated by efferent (motor) neurons   gamma  D. All    ****** E. none Muscle spindle motor intervention: why would a sensory receptor need/want 
motor intervention? What does it do?
A. The best stimulus is stretch ************
B. The spindle scenes stretch and tension
C. Contraction of intrafusal fibers contributes to total muscle tension
background image D. Spindle fibers are additional motor units E. This is a vestige of evolution, like appendix and the coccyx   ­Firing Gamma motor neurons does not produce tension 
­spindle only sense one of the two stimuli 
4. Describe the muscle spindle’s role in proprioception o Muscle spindles are  length detectors   o Fire tonically (afferents fire constantly for nervous system tone)  Lengthen muscle = firing frequency will increase * Shorten muscle = firing frequency will decrease  o Report  statically and rate of change of length  4. Describe the Golgi tendon organ’s role in proprioception Tension­monitoring Systems: o Golgi Tendon Organs Located in the  tendons Monitor tension  in the tendons Respond most to tension on tendon DUE TO 
CONTRACTING MUSCLE
Activation of GTOs can cause: Inhibition of the contracting muscle and its synergists Activation of antagonist muscles Interneurons involved 6.  List tracts making up the Ventromedial (VM) and Dorsolateral (DL) pathways o Middle” Level of Movement Control Subcortical and brainstem nuclei influence movement A functional method to categorize descending pathways controlling 
spinal interneurons and motor neurons is:
Dorsolateral  Pathway

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School: University of Connecticut
Department: Physiology
Course: Human Physiology and Anatomy
Professor: Kristen Kimball
Term: Fall 2018
Tags:
Name: PNB 2264 week 10
Description: These notes cover class power-points and objectives.
Uploaded: 11/09/2018
7 Pages 71 Views 56 Unlocks
  • Better Grades Guarantee
  • 24/7 Homework help
  • Notes, Study Guides, Flashcards + More!
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