CONTROL OF MOVEMENT: STRIATED MUSCLES
Transcript of CONTROL OF MOVEMENT: STRIATED MUSCLES
ANATOMY OF SKELETAL MUSCLE
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Extrafusal muscle fiber
Myofibril
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CONTROL OF MOVEMENT: STRIATED MUSCLESSKELETAL (STRIATED) MUSCLE:
- each muscle = ____________________________________- each muscle cell = _______________________________________- Myosin: ___________________________________________- Actin: _________________________________________________
Filamentous protein with ross bridgesFilamentous protein where cross bridges of myosin bind
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MUSCLE CONTRACTION
Myosincrossbridges
Actinfilaments
Myosinfilament
Actinfilament
Movement ofactin filament
Myosincrossbridge
Movement ofmyosin filament
Heads of cross bridges:1. Attach to active sites on actin filaments2. “Ratchet” forward3. Release4. Repeat- Only occurs in the presence of ________How is calcium released? ___________________________
________From activity at neuromuscularjunction
Watch muscle contraction movie
NEUROMUSCULAR JUNCTIONSynapse between terminal of _________________and a ___________ is called a neuromuscularjunction;
Terminals of alpha motor neurons synapse on_____________- grooves along the surface ofmuscle fibers;
When motor neuron fires, _____________ isliberated from terminals at the endplate anddepolarizes muscle fibers - ________________;
Depolarization of muscle fiber opens _________________________________, producing a largecalcium influx into the fiber;
Calcium triggers the actin-myosin “rowing”action leading to the __________ of muscle fibers;
Calcium is extruded from fiber by “pump”;
Endplate potential ______ cause muscle fiber tofire = contraction or “twitch” of fiber.
MOTOR UNITS
- weak muscular contraction = _______________________- strong contraction = _______________________- discrete/fine movements = __________________________
____________- crude/gross movements = __________________________
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Alpha motor neurons
Muscle fibers
Motor unit: __________________________________________________________________________
Motor pool: All motor neurons that innervate fibers of a single muscle.
Axons
Localization and distribution of motor neurons in the spinal cord
Somatosensory (mechano) and nociceptive (pain) receptors
Glabrous skin: _________________________________Hairy skin: __________________________________
There are 3 groups of somatosensory receptors:
1. ______________ 2. ______________ 3. ______________
skin that covers the rest of the body
Somatosensory pathway from receptors to somatosensory (primary) cortex:
How pain reaches the somatosensory cortex
How is the phenomenon of “referred pain” produced?
Arm and shoulder pain “referred” from heart pain receptors during heart attack.
MONOSYNAPTIC STRETCH REFLEXInvolves:- _________________- _________________________________- __________________________________________________________________
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Watch stretch reflex movie
How muscle spindles work!- Gamma motor neurons provide the ________
________________________________- without gamma motor neurons, the spindles
would become _________________________________________
- gamma motor neurons function _________________________________ to an appropriatedegree of tension
Muscle spindles
Gamma motor neurons
Spindle “slack” - insensitive to strech Spindle “tight” - ready to respondto strech
Extrafusal muscle
“slack” and unresponsiveto stretch.
to adjust the length of intrafusal muscles
POLYSYNAPTIC REFLEXES:EXAMPLE OF WITHDRAWAL FROM PAIN
- reflexes requiring _________________________- concept of _______________________________
____________________________- ex., biceps vs. triceps of arms
- reciprocal innervation (excitatory vs. inhibitory)- ____________________________________________________________________________excitatory and inhibitory interneurons worktogether to withdraw limb from pain.
CROSSED EXTENSOR REFLEX
Think of this reflex as being ____________ withprevious polysynaptic withdrawal reflex
For example, if flexion reflex triggered in oneleg, ___________________________________
All this happens _________________________;the brain has nothing to do with it.
This serves to:- ______________________________________________________________
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An example of a complex sensorimotor reflex is________.- spinal cat, when placed on a treadmill can
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“connected”
help remove or push entire body away from painful stimulus;
help restore balance when flexed leg is withdrawn.
initiate normal walking when provided with somatosensory feedback of treadmill on feet.
GOLGI TENDON REFLEXor how not to shred your muscles and bones!
Golgi Tendon Organ: ___________________________________________________________________________________________
- only contacts ________________________- if maximally activated, ___________________
________________________________- helps prevent tearing of muscles and tendonsfrom bone
receptor organ sensitive to stretch and located at the junction of the tendon and muscle.
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Golgi tendonorgan
Pseudounipolarneuron
inhibitory interneuron
alpha motor neuron