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BIPN 100 FINAL
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BIPN 100 FINAL BIPN 100 FINAL BIPN 100 FINAL
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BIPN 100 FINAL examhow do we coordinate movement? - verified answer 1) reflexes
2) voluntary movement
3) rhythmic movement
Corticospinal (pyramidal) tract - verified answer mediate voluntary movement; descending tract
lateral corticospinal tract - verified answer limb movement; decussates in medulla pyramids
anterior corticospinal tract - verified answer axial muscles (trunk, neck, shoulders); decussates in
segment
pyramidal decussation - verified answer location at which corticospinal tract fibers cross the
midline and segregate into the anterior and lateral divisions of the pathway
lower motor neurons - verified answer topographically organized; synapse directly on muscles
(excitatory signals only)
medial spinal cord - verified answer proximal muscles
lateral spinal cord - verified answer distal muscles
phases of voluntary movement - verified answer planning, initiating, executing
planning - verified answer basal ganglia, cortical association areas, cerebellum
initiating - verified answer motor cortex (includes feedback loops back into planning)
executing - verified answer cerebellum and movement (includes feedback loop back into motor
cortex)
control of voluntary movements - verified answer 1) sensor input (sensory cortex)
,2) planning and decision-making (prefrontal cortex, motor association areas, basal ganglia, thalamus)
3) coordination and timing (cerebellar input)
4) execution: corticospinal tract to skeletal muscles (brain stem)
5) execution: extrapyramidal influence on posture, balance, and gait
3+4+5 = muscle contraction
6) continuous feedback (sensory receptors)
monosynaptic reflex (stretch) - verified answer Reflex pathway with only one synapse between the
sensory and motor neurons (ex: muscle spindle reflex).
extrafusal muscle fibers - verified answer motor neurons synapse on here; responsible for force
exerted by contraction of skeletal muscle
alpha motor neuron - verified answer A neuron whose axon forms synapses with extrafusal muscle
fibers of a skeletal muscle; activation contracts the muscle fibers.
golgi tendon organ - verified answer the receptor organ at the junction of the tendon and muscle
that is sensitive to stretch; sensory nerve endings interwoven among collagen fibers inside of a
tendon
tendon - verified answer Connects muscle to bone
muscle spindle - verified answer a sensory receptor located in a muscle that senses its tension;
buried among extrafusal fibers
intrafusal fibers - verified answer modified muscle fibers within the spindle; tonically active sensory
neurons (all or nothing) always firing except when intrafusal muscle spindles contract
intrafusal vs extrafusal muscle fibers - verified answer - when extrafusal muscle fibers contract,
muscle is contracting
- when intrafusal muscle fibers contract, no impact on the tension of the larger muscle; control of
stretch
, muscle spindle reflex - verified answer sensory neurons detect stretch -> send info to motor
neuron -> motor neuron sends axon to extrafusal muscle -> tells muscle to contract
stretch reflex in relaxed state - verified answer 1) extrafusal muscle fibers at resting length
2) sensory neuron tonically active
3) sensory neuron tonically releasing NT onto motor neurons
4) alpha motor neurons to extrafusal fibers release NT
5) extrafusal fibers maintain resting tone
stretch reflex negative feedback - verified answer muscle stretch -> increased afferent APs -> spinal
cord -> increased efferent APs alpha motor neurons -> muscle contracts -> decrease APs of afferent
sensory neuron
stretch reflex without gamma activation - verified answer 1. Alpha motor neuron fires
2. Muscle contracts
3. Less stretch on center of intrafusal fibers
4. Firing rate of spindle sensory neuron decreases
stretch reflex: alpha gamma co activation (top-down control) - verified answer 1) alpha and gamma
motor neuron fire (co-activation)
- muscle is stretched, the muscle spindle stretches and the alpha motor neuron fires more strongly
- muscle contracts, muscle spindle becomes slack, alpha firing slows
- gamma motor neuron fire and cause spindle to contract
2) extrafusal muscle (alpha) and intrafusal fibers (gamma) both contract
3) stretch on intrafusal fibers unchanged; firing rate of sensory neuron remains constant
polysnaptic reflex - verified answer involves more than one synapse; makes motor neuron fire
fewer APs, so muscle is not going to contract (ex: golgi tendon reflex)
Golgi tendon reflex - verified answer 1. neuron from golgi tendon organ fires
2. motor neuron is inhibited
3. muscle relaxes
4. load is dropped
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