neuromuscular physiology

Question 1

ventral

Answer 1

anterior

Question 2

dorsal

Answer 2

posterior

Question 3

motor neurons are _______ neurons and run through the _______ horn

Answer 3

efferent, ventral/anterior

Question 4

sensory neurons are _______ neurons and run through the ______ horn

Answer 4

afferent, dorsal/posterior

Question 5

interneurons

Answer 5

within the CNS that communicate with other neurons. never leave the CNS

Question 6

What are the two types of sensory neurons and how are they alike or different

Answer 6

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.

Question 7

what are the two major pathways that motor signals travels through

Answer 7

pyramidal and extrapyramidal

pyramidal is impulses traveling downward through the spin

watch this
https://www.osmosis.org/learn/Pyramidal_and_extrapyramidal_tracts

Question 8

Describe how the reflex arc works

Answer 8

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.

Question 9

how many fibers in gross movements

Answer 9

lots per neuron

Question 10

how many fibers in fine motor movements

Answer 10

few per neuron

Question 11

a motor unit is

Answer 11

the alpha motor neuron and all the muscle fibers that it innervates

Question 12

what type of channels are the sodium channels in a post synaptic cleft

Answer 12

ligand gated because acetyl coa (traveling from the pre synaptic cleft) is causing the channels to open .

Question 13

motor pool

Answer 13

all alpha motor neurons that project to a given muscle collectively.
example: all motor neurons that innervate the bicep muscles = motor pool

Question 14

what is the 10% rule in motor pools

Answer 14

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

Question 15

What is size principle

Answer 15

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.

Question 16

What defines the size of a motor unit

Answer 16

smallest soma
fewest dendrites
innervation of the fewest muscle fibers
generate smallest amount of force.

Question 17

What is the size principle using excitatory expanation

Answer 17

the motor units in a pool that require the least amount of excitatory current to reach their activation threshold will be innervated first

Question 18

What is the function of a muscle spindle

Answer 18

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)

Question 19

What are mechanoreceptors

Answer 19

receptors that tell your nervous system where your body is in space at any given time

Question 20

Golgi tendno organs

Answer 20

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.

Question 21

Difference between intrafusal and extrafusal fibers

Answer 21

intrafusal fibers are between extrafusal fibers and ar prioprioceptive whereas extrafusal fibers surround intrafusal fibers and are mechanical and move the bones

Question 22

nuclear bag fiber vs nuclear chain fiber

Answer 22

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

Question 23

What is the difference between type 1a and type 2 fibers

Answer 23

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

Question 24

how do intrafusal fibers work

Answer 24

they send impulses to spinal chord through dorsal (posterior) horn and the CNS sends info back causing muscl to shorten and relax.