Reflexes

Question 1

Why does reflex inhibition occur

Answer 1

to prevent muscle damage

Question 2

what is stimulated in stretch reflex

Answer 2

Muscle spindles

Question 3

whats the steps of the stretch reflex when a heavy load is applied

Answer 3

Load applied 
Muscle stretches
arm extends 
fires AP 
activates muscle spindles 
agonist muscle contracts
restores arms position

Question 4

What kind of reflex is a stretch reflex

Answer 4

monosynaptic reflex

Question 5

What is reciporcal inhibition

Answer 5

For the agonist flexor muscle to contract in a reflex the antagonist flexor must relax

Question 6

What are the two neurones involved in a monosynaptic reflex

Answer 6

sensory neurone from the muscle spindle and the motor neurone from muscle

Question 7

What is the best example of a stretch reflex

Answer 7

knee jerk reflex

Question 8

where does spindle afferent information go

Answer 8

connects with somatosensory cortex

Question 9

What stimulates the inverse stretch reflex

Answer 9

Golgi tendon organ

Question 10

What is inhibited in a inverse stretch reflex

Answer 10

motor neurones

Question 11

what happens in an inverse stretch reflex when muscles are contracting and a heavier load is applied

Answer 11

Tendons are pulled, causing GTO to fire AP
this causes agonist flexor muscle to relax and antagonist flexor muscle to contract
the arm relaxes and drops load

Question 12

What is the purpose of inverse stretch reflex

Answer 12

presents muscle contracting to much to cause damage

Question 13

How can a inverse stretch reflex be overridden

Answer 13

if load being carried is of significant importance

Question 14

what does a flexor (withdrawal) reflex do

Answer 14

use information from pain receptors to withdraw body away from painful stimuli

Question 15

What reflexes are polysynaptic

Answer 15

Flexor refelx

inverse stretch reflex

Question 16

What is the pathway of a flexor reflex to the spinal chord

Answer 16

Pain stimuli 
activates noiceptor 
sensory spinal chord 
Diverging pathways 
agonist muscle flexor contracts 
etc

Question 17

What are the different pathways of flexor-crossed extensor reflex

Answer 17

1. Pain signal sent
2. excites flexor agonist mn (leg1)
3. inhibits flexor antagonist mn (leg2)
4. inhibits extensors of agonist mn (leg1)
5. exhibits extensors of antagonist mn (leg2)

Question 18

What does crossed extensor reflex do

Answer 18

Maintain posture and balance

Question 19

Explain crossed extensor reflex

Answer 19

extensors contract on the antagonist leg allowing balance to be maintained as agonist muscle extensor relaxes to be removed away from painful stimuli
(external limb bears the weight)

Question 20

Why is flexor-crossed extensor reflex far slower than stretch reflex

Answer 20

polysynaptic

nociceptive sensory fibres have smaller diameter than muscle spindle afferents and so conduct more slowly

Question 21

What is facilitation

Answer 21

the more painful the stimuli the greater the response, as more alpha mn are in depolarised state

Question 22

Spastic is

Answer 22

high γ-motoneurone activation of muscle spindles

Question 23

what is ipsilateral flexion

Answer 23

Flexion on the same side

Question 24

What is the difference between ipsilateral and crossed flexion

Answer 24

crossed involves two limbs