neuromuscular physiology Flashcards
ventral
anterior
dorsal
posterior
motor neurons are _______ neurons and run through the _______ horn
efferent, ventral/anterior
sensory neurons are _______ neurons and run through the ______ horn
afferent, dorsal/posterior
interneurons
within the CNS that communicate with other neurons. never leave the CNS
What are the two types of sensory neurons and how are they alike or different
conscious and subconscious
conscious monitor external environment and have sensitivity to body position as well as sensations such as temperature, light, sound, smell, tase, touch and pain
subconscious monitor changes to internal environment and include chemoreceptors for blood gas (PO2 and PCO2) as well as baroreceptors that react to changes in BP. Also pH receptors.
what are the two major pathways that motor signals travels through
pyramidal and extrapyramidal
pyramidal is impulses traveling downward through the spin
watch this
https://www.osmosis.org/learn/Pyramidal_and_extrapyramidal_tracts
Describe how the reflex arc works
1.sensory input comes through peripheral receptors and afferent neurons enter the spinal cord through the dorsal root.
2. interneurons relay information to different levels of the cord
3. impulses the pass over the motor (efferent) pathway to the effector organ and create a movement if needed.
how many fibers in gross movements
lots per neuron
how many fibers in fine motor movements
few per neuron
a motor unit is
the alpha motor neuron and all the muscle fibers that it innervates
what type of channels are the sodium channels in a post synaptic cleft
ligand gated because acetyl coa (traveling from the pre synaptic cleft) is causing the channels to open .
motor pool
all alpha motor neurons that project to a given muscle collectively.
example: all motor neurons that innervate the bicep muscles = motor pool
what is the 10% rule in motor pools
each motor unit in a pool generates about the same amount of force. There is less than 10% variance between motor units in a motor pool
What is size principle
within a single motor pool, motor neurons will be recruited in the order of ascending size. This being the smallest unites first and the largest units last. regardless of the type of effort.
What defines the size of a motor unit
smallest soma
fewest dendrites
innervation of the fewest muscle fibers
generate smallest amount of force.
What is the size principle using excitatory expanation
the motor units in a pool that require the least amount of excitatory current to reach their activation threshold will be innervated first
What is the function of a muscle spindle
to measure the velocity of muscle stretch and react accordingly if stretch is occurring to quickly or too much. ( look at drawing on katelyns outline seriously dont skip this billie)
What are mechanoreceptors
receptors that tell your nervous system where your body is in space at any given time
Golgi tendno organs
sense TENSION in the muscle and stops muscle from contracting before the muscle tears. This can be done by either inhibiting the contracting muscle or exciting an antagonizing muscle.
Difference between intrafusal and extrafusal fibers
intrafusal fibers are between extrafusal fibers and ar prioprioceptive whereas extrafusal fibers surround intrafusal fibers and are mechanical and move the bones
nuclear bag fiber vs nuclear chain fiber
nuclear bag fiber has all of the nuclei gathered in the center “bag” and are sensitive to length AND velocity
nuclear chain fibers have spread out nuclei and are only sensitive to length
What is the difference between type 1a and type 2 fibers
both are sensitive to stretching however type 1a (annulopsiral endings) respond to a more dynamic change in length such as tendon taps and vibration whereas type 2 (flower spray endings ) are more sensitive to static response to changes in lenth such as posture
how do intrafusal fibers work
they send impulses to spinal chord through dorsal (posterior) horn and the CNS sends info back causing muscl to shorten and relax.
