Reflex Control of Movement

Question 1

Function of spinal reflexes

Answer 1

adjust for unexpected disturbances
provide rapid protection
provide basic motor patterns used in locomotion (voluntary)

Question 2

4 characteristics of spinal reflexes

Answer 2

Graded, stereotyped, rapid, involuntary

Question 3

reflex pathway components (4)

Answer 3

afferent input
central processing
efferent output
comparison of different spinal reflex pathways

Question 4

reflex latency

Answer 4

fixed latency for a given reflex pathway

stimulus onset -> response

Question 5

latency depends on

Answer 5

length of pathway
number of synapses
conduction velocity

Question 6

simplest spinal reflex

Answer 6

spinal stretch reflex

monosynaptic, 25-30ms

Question 7

how long is monosynaptic reflex

Answer 7

25-30ms

Question 8

divergence of Ia input

Answer 8

homonymous muscle and synergistic muscles contract

antagonistic muscles relax (inhibitory interneurons)

Question 9

function of spinal stretch reflex

Answer 9

maintain muscle length
sensory: muscle spindles
negative feedback

Question 10

how can strength of reflex be regulated

Answer 10

reflex gain control

Question 11

what is gain

Answer 11

output efferent / input afferent

Question 12

muscle tone

Answer 12

reflects reflex gain

Question 13

hypertonia and hypotonia

Answer 13

high and low reflex gain

Question 14

how is reflex gain regulated

Answer 14

1. increase or decrease excitatory input to alpha mns
2. presynaptic modulation of input to alpha mns
3. fusimotor drive (not affect gain but increase output)

Question 15

what does jendrassik maneuver do to gain

Answer 15

increases gain

Question 16

long-loop relfexes (long latency) how long

Answer 16

50-60 ms

Question 17

what pathway is long loop

Answer 17

polysynaptic - cerebral cortex

Question 18

Is long-loo functional stretch reflex

Answer 18

yes

Question 19

does long loop generate less or more compensatory force than spinal stretch reflex

Answer 19

more