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Medicine Term One > Reflexes > Flashcards

Flashcards in Reflexes Deck (24)
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1
Q

Why does reflex inhibition occur

A

to prevent muscle damage

2
Q

what is stimulated in stretch reflex

A

Muscle spindles

3
Q

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

A
Load applied 
Muscle stretches
arm extends 
fires AP 
activates muscle spindles 
agonist muscle contracts
restores arms position
4
Q

What kind of reflex is a stretch reflex

A

monosynaptic reflex

5
Q

What is reciporcal inhibition

A

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

6
Q

What are the two neurones involved in a monosynaptic reflex

A

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

7
Q

What is the best example of a stretch reflex

A

knee jerk reflex

8
Q

where does spindle afferent information go

A

connects with somatosensory cortex

9
Q

What stimulates the inverse stretch reflex

A

Golgi tendon organ

10
Q

What is inhibited in a inverse stretch reflex

A

motor neurones

11
Q

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

A

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

12
Q

What is the purpose of inverse stretch reflex

A

presents muscle contracting to much to cause damage

13
Q

How can a inverse stretch reflex be overridden

A

if load being carried is of significant importance

14
Q

what does a flexor (withdrawal) reflex do

A

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

15
Q

What reflexes are polysynaptic

A

Flexor refelx

inverse stretch reflex

16
Q

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

A
Pain stimuli 
activates noiceptor 
sensory spinal chord 
Diverging pathways 
agonist muscle flexor contracts 
etc
17
Q

What are the different pathways of flexor-crossed extensor reflex

A
  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)
18
Q

What does crossed extensor reflex do

A

Maintain posture and balance

19
Q

Explain crossed extensor reflex

A

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)

20
Q

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

A

polysynaptic

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

21
Q

What is facilitation

A

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

22
Q

Spastic is

A

high γ-motoneurone activation of muscle spindles

23
Q

what is ipsilateral flexion

A

Flexion on the same side

24
Q

What is the difference between ipsilateral and crossed flexion

A

crossed involves two limbs

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