Neuromuscular Basis Of Human Movement Flashcards
Nerve impulse (action potential)
The signal that passes from one neuron to the next and finally the end organ (muscle fibers)
Pathway of Nerve Impulse
Travels from cell body to axon to terminal
Resting membrane potential
Dynamic equilibrium at -70mV
Potassium inside, sodium outside
Polarized membrane
Depolarization
Nerves transmit information by changing the potential across the membrane
RMP moves closer to 0mV
Threshold
Before a nerve can be depolarized and an AP started, there must be sufficient stimulation
Typical nerve threshold = -55mV
No threshold = no AP
Afférent Pathways
Afférent neurons send sensory information to the CNS
Efferent Pathways
Efferent neurons send executing information to periphery
CNS
Brain, spinal cord, human movement initiated, controlled, and monitored
PNS
Branching nerves outside of spinal cord
Neuron
Functional unit of the nervous system
Motor neurons
Carry signals to muscle
Afferent neurons
Ascending into to spinal cord and brain
Efferent neurons
Descending info from CNS/spinal cord to muscles
Interneurons
Afférent to efférent
Efférent to efferent
Higher centers to spinal cords
Soma
Body of cell
Ganglia
Bundles or cell bodies just outside the spinal cord
Dendrites
Projections on the cell body that serve as receivers
Axon
Large nerve fiber that branches out from spinal cord
Alpha motor neuron
Large, rapidly transmitting neuron
Myelinated
Covered with an insulated shell
Schwann cells
Insulation enveloping specific section of axon
Node of Ranvier
Gap in between Schwann cells
Synapse
Small gap between terminal branch of neuron and muscle
Motor unit
Composed of a motor neuron and all of the muscle fibers it innervates
Motor unit fibers
of fibers depends on the precision of movement required of that muscle
# of motor units decreases with age
All or none principle
When motor units receive sufficient stimulation, all fibers of a motor unit produce tension together
Recruitment
Increasing the # of stimulated motor units
Rate coding
Increasing the stimulation rate of the active motor units
Rate coding - twitch
The effect of a single stimulus
Rate coding - summation
The overall effect of added stimuli