reflexes

Question 1

where is the stretch reflex found
and where does its info come from

Answer 1

all muscles

muscle spindles

Question 2

example of a stretch reflex

Answer 2

knee jerk

tapping force is transferred from the less elastic tendon to the more elastic muscle

Question 3

knee jerk stretch triggers

Answer 3

Ia afferent sensory neuron in the spindle

increases action potentials in to spine- triggers agonist muscle to contract

and antagonist muscle relaxes due to reciprocal inhibition

Question 4

3 types of connections that sensory afferents make

Answer 4

1. direct contact to alpha motor neurons in stretched muscle- contracts agonist muscle
2. monosynaptic reflex
3. indirectly with antagonists from stretched spindle

Question 5

reciprocal inhibition

Answer 5

when the agonist contracts the antagonist relaxes

due to spindle afferents activating inhibitory interneurons

which lower activation of alpha motoneurons

Question 6

inverse stretch reflex

Answer 6

muscle contracts and shortens pulling:

the tendon and sensory Ib afferent nerves from the golgi tendon organ

increasing action potentials

Question 7

inverse stretch reflex causes

Answer 7

1. activation of inhibitory interneurons in the agonist muscle- decreases strength
   
   1. activation of excitatory interneurons in antagonist muscles
2. information is sent to the somatosensory cortex

Question 8

whats the point of the inverse stretch reflex

Answer 8

protective to prevent muscle damage

Question 9

withdrawal reflex uses information from

Answer 9

pain receptors

Question 10

how does the withdrawal reflex work

Answer 10

increased action potentials in nociceptors cause:

1. increased activity in flexor muscle
2. antagonist extensors are inhibited
3. contralateral extensors are excited- prevents falling over
4. contralateral flexors are inhibited
5. sensory info goes to brain via contralateral spinothalamic tract

(flexor to be excited and extensor inhibited

the opposite on the other side)

Question 11

where does the withdrawal reflex occur

Answer 11

only in the spine

Question 12

withdrawal reflex is also called

Answer 12

flexor reflex

Question 13

withdrawal reflex vs stretch for speed

Answer 13

withdrawal is slower- uses more interneurons and nociceptors conduct slower than muscle spindles

Question 14

how can the inverse stretch reflex be overridden

Answer 14

each alpha motor neuron receives loads of synapses, some from the thalamus and cortex

it has to integrate all the signals and produces the net affect

so extra ecitation from brain can stop the inhibition

Question 15

what other reflexes can be overridden

Answer 15

stretch

withdrawal