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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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