Neurophysiology Test 3

_________ ________: Moves bones around joints; Moves eyes in skull; Controls respiration; Controls facial expression; Produces speech; enclosed in connective tissue sheaths.

______ _______ ______: somatic muscle innervated by somatic motor neurons in the ventral horn of spinal cord.

Bundles of LMN= ________ _______: join with dorsal roots to form spinal nerve that exits SC= contain sensory and motor, thus they are mixed spinal nerves.

________ Ventral Horn: innervates axial muscles

________ Ventral Horn: innervates distal muscles

________ Ventral Horn: innervates flexors.
________ Ventral Horn: innervates flexors.

______ Motor Neuron: trigger force of muscle

_____ _______ _______: collection of alpha motor neuron innervating 1 muscle.

_____ _____ _____: ( effects presynaptic AP) causes EPSP's in muscle fibers (endplate potential) and triggers AP in muscle. Results in muscle twitch. Twitch summation causes increased tension in muscle fibers and smooth contraction.

_______ _______: high frequency with barrage of AP's resulting in postsynaptic responses.

Recruiting of additional synergistic motor units results in extra _____ on a muscle.

Muscle recruitment goes from ____ to ______.

_____ _____: slow to contract; can sustain contraction long time; found in antigravity muscles of leg.

_____ _____: fast to contract; rapid fatigue; escape muscles (jump, run, human arm)

True or False: each type of motor units coexist in a given musle but motor units contains only single type.
True False

_____ motor units: rapid fatiguing white fibers; larger axons= faster axons; occasional high frequency bursts of AP's.

_______ motor units: slow fatiguing red fibers; smaller axons= slower axons; steady low threshold.

True or False: Muscle fiber type cannot be changed.
True False

________ ______ Contraction: AP's in presynaptic membrane release Ach from pre- into cleft. This activates nicotinic Ach receptors on post-synaptic membrane (EPSP's). Causes AP in muscle fiber and triggers Ca2+ release from organelle and contraction of fiber.

_________: excitable membrane enclosing muscle fibers

_______: within muscle fibers; cylindrical, contract due to AP going down sarcolemma and surrounded by Sarcoplasmic Reticulum which Ca2+.

AP enters sarcoplasmic reticulum by tunnel: _____ _____

_______: voltage sensitive cluster of 4 Ca2+ channels linked to calcium release channel in SR

____ lines: myofibril divided into segments by disks.
_______: Z lines and myofibril in between.
_____ _____: anchored to Z line.
______ _____: between thin filaments.
______ ______: thin filaments slide along thick filaments bringing Z lines closer= shortens sarcomere= Sliding Filament Model

Sliding filament model: occurs due to interaction between ____ and ____.

Myosin can't bind to actin as actin sites are covered by _____.

_____ ______: stretch receptor; special skeletal muscle fibers in fibrous capsule in parallel with muscle fibers. Middle is " swollen".

____sensory axons: larges and fastest, enter SC via dorsal root adn form synapses on interneurons and alpha motor neurons of ventral horn.

_____ ______ reflex: increase synapse separates sensory input from motor neuron output.

_______ _______: weight on a muscle causes muscle spindle to stretch which depolarizes 1a endings and depolarizes alpha motor neurons. This increases AP in motor neurons and muscle contracts.

_______ Fibers: great number of fibers outside of spindle (muscle bulk) innervated by alpha motor neurons.
_______ Fibers: modified skeletal fibers in muscle spindle; innervated by gamma motor neurons

_____ Loop: gamma motor neuron--> intrafusal muscle fiber--> 1a afferent--> alpha motor neuron--> extrafusal muscle fiber--> repeat

____ _____ ____: proprioception, monitors force of contraction; located at junction on muscle and tendon; innervated by 1b afferents in series with muscle fibers.

_____ _____ _____: some inhibitory to alpha motor neurons that innervate same muscle. protects muscle from overload and regulates muscle tension in optimal range.

____ _____: respond to change in angle, direction, and velocity of movement of joint.

______ ______: myotatic reflex involves contraction of flexors and also relaxation of antagonist.

______: descending control destroyed

_____ _____: withdraw limb from pain

__ ___ ___: activates extensors and inhibits flexors of opposite limb

_____ of _____: maintians muscle bulk, helps support circulatory function, assist in activities of daily living, may assist with postural control