motor system I&II Pearson

Question 1

neurons that innervate motor units

Answer 1

alpha motor neurons

Question 2

components of a motor unit

Answer 2

one neuron which innervates several muscle fibers

Question 3

sow motor untis

Answer 3

generate small forces, think gentle touch. The neurons are smaller, the axons are thinner, less oxidation muscle fibers are innervated. In general, these units make small forces, and fatigue slowly. They are recruited first

Question 4

fast fatigue resistant

Answer 4

Generate large forces, but fatigue slowly. These are recruited second

Question 5

Fast fatigue

Answer 5

The big dogs. Strong, fatigue fast, last to be recruited. Hulk status - light weight baby! One fat neuron innervates a small city of fibers.

Question 6

Why are different fibers recruited in different orders

Answer 6

it allows the amount of force and energy expenditure to be controlled and tuned to meet the demands of a given situation

Question 7

Why are small neurons depolarized first?

Answer 7

Ohms law. Small neurons depolarize first, where as large neurons take a lot of stimulation to depolarize. This allows the body the activate the small neurons, and small muscle fibers first.

Question 8

summation of epsp does what?

Answer 8

totals up the signal to activate the big dogs! means the large fibers are activated

Question 9

what happens when fibers are innervated by other neurons?

Answer 9

The fibers change their role. Slow soft can become fast strong. Transition from white to red, or red to white, or big to small - etc.

Question 10

effect of endurance training?

Answer 10

increases fatigue resistant fibers

Question 11

effect of lifting?

Answer 11

get huge. strong forces, but fast fatigue

Question 12

intrafusal muscle fiber

Answer 12

are contractile muscle fibers, but not enough o generate force. These fibers are the sensory mechanotransduction fibers. These things also receive innervation from gamma motor neurons.

Question 13

extrafusal muscle fibers

Answer 13

these are the force generating fibers

Question 14

what happens when muscle is unexpectedly stretched?

Answer 14

the gamma transmit signal to the spinal chord, which uses and interneuron to synapse on the alphas neurons, then the alphas contract the muscle to resist the stretch

Question 15

stretch reflex?

Answer 15

when a muscle is stretched, it contracts to resist.

Question 16

tone?

Answer 16

all fibers are constantly stimulated at a basal rate, lading to muscle tone

Question 17

reciprocal innervation

Answer 17

only the same muscle that is stretched is the muscle that contracts via the stretch reflex. Also, inhibitory interneurons case opposing muscle groups to relax.

Question 18

what happens when muscle is signaled to contract (think both intrafusal and extrafusal)

Answer 18

both units contract.

Question 19

reflexive shortening on contraction

Answer 19

look it up

Question 20

error correction

Answer 20

voluntary contraction contracts both alpha and gamma. the gamma are reortsing back on tone, and the relationship is stable if stretch and contraction are equal. If contraction exceeds stretch, relaxation is noted by the itrafuasal fiber. The slack causes a drop in fiber rate, which decreases the force being applied. Converse is true too, not enough force leads to intrafual stretch, and feedback causes increased contraction.

If have an older brother, you maybe familiar with ways to circumvent this problem and cause your siblings to hit themselves in the face.

Question 21

1b afferent fibers

Answer 21

stretch neuron in tendon golgi organs

Question 22

golgi tendon organ

Answer 22

1b afferent neuron located in tendons which lead to inhibition to muscle becoming slack, and tenses the opposing muscle group

Question 23

compare muscle spindle to golgi tendon organ

Answer 23

golgis: in sries with muscle, preferentially signal muscle tensin, important for stablizing contcations, composed of collagen fibers and capsule, signals via Ib afferent, not cotractile
spindle: in parrallel with muscle. signals muscle stretch, important for muscle tone, composed of muscle fibers, signals via Ia afferents, innervated by gamma motor neurons

Question 24

crossed extensor-flexor coupling

Answer 24

relaxation of appendage sensing nocioceptive stimuli, while contralateral appendage contracts. Allows flexion of hurt appendage (retraction) while appropriate extension is initiated on the opposite side. In summery, you will not fall over when you step on a tac.

Question 25

locomoter patterning

Answer 25

means while one leg has activation of extensor, the extenros is inhibited in the opposite leg. This is mediated by collateral neurons in the spinal cord.

Question 26

central pattern generators

Answer 26

coordination of many locomoter patterns that allows the coordination of gate.

Question 27

pattering after spinal cord injury?

Answer 27

tots. The central patterning can work after an animal is paralzyed. Means this is coded at the level of the spinal cord.

dopamine or afferent sensory stim can help this process, but this happens without these stimuli, meaning sensory feedback is not important for central patterning.

Question 28

spinal prep

Answer 28

look it up

Question 29

deafferented preparation

Answer 29

look it up

Question 30

decerebrate preparation

Answer 30

look it up

Question 31

lower motor neuron syndrome

Answer 31

damage to lower motor neuron cell bodies (ie alpha neurons). Paralysis, paresis, loss of reflex, loss of muscle tone, atrophy, spontaneous switches as muscles become deinnervated.

Question 32

causes of LMNS

Answer 32

syphilis, dorsal root ganglia
herniated disk, pinch nerve roots
polio/als, motor neuron degeneration
guillian barre, demyelination of periferal nerve
lambert-eaton, ca channel immune target
myesthinea gravis
DMD

Question 33

brainstem control of movement

Answer 33

organization axial musculature
maintain balance
regulate posture
orient gaze

Question 34

mesencaphilic locomoter center

Answer 34

causes locomotion originating in the brain stem.
reticulospinal tract
vestibulospinal tract
VOR circuitry

Question 35

reticulospinal tract

Answer 35

riinates around the pons, stops in the medial vetral horn. Used for balance correction. If you torture cats, as they deserve to be tortured, the cats will not have balance.

Question 36

vestibulospinal tract

Answer 36

originates in the innerear, detects tilt, and then send s the info to the rest of the body. Maintains balance. This is activated in unexpected falls. Vestibulospinal reflex. Fall and put hand down without thinking

Question 37

Vor circuitry

Answer 37

cant track objects as they move faster. Can organize eye movement.