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Science for Medicine > Reflexes > Flashcards

Flashcards in Reflexes Deck (14)
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1
Q

How is the stretch reflex elicited and how does it work?

A

By a sharp tap to the tendons which are inelastic, so the force is transferred tot he muscle fibres which stretch and stimulate the spindles

2
Q

What is activated by the stretch reflex?
What does this cause?
What is this the only known example of?

A

Alpha motoneurones

agonist muscle to contract

a monosynaptic reflex

3
Q

What must happen in the stretch reflex since muscles work in pairs?

A

The antagonist muscle must also relax during the reflex
- because the spindle afferents activate inhibitory interneurons which decrease alpha motoneurone transmission to the antagonist

4
Q

What is the reflex mediated by the Golgi tendon organs?

A

Inverse stretch/clasp-knife reflex

5
Q

As the muscle contracts, it pulls on the tendons and the Golgi tendon bodies

A

increase their discharge

6
Q

Increased discharge from the Golgi tendon bodies activates ___ and ___

A

inhibitory interneurons to the agonist muscle

decreases the contraction strength

7
Q

Increased discharge from the Golgi tendon organs also

A

activates excitatory interneurons to the antagonistic muscle

8
Q

The inverse stretch reflex is ___

It ___

A

polysynaptic and protective

prevents over contraction and prevents the muscle from tearing the tendon insertion points away from the bones

9
Q

What does the flexor-withdrawal reflex use?

A

information from the nociceptors in skin, muscle and joints

10
Q

Flexor-withdrawal reflexes are

A

polysynaptic and withdraw the affected part of the body away from the stimulus and towards the body

11
Q

Sensory stimulus causes

A

an increase in activity of flexor muscles via a number of excitatory interneurons

12
Q

Inhibitory neurones work on

A

antagonistic extensors

13
Q

If the flexor-withdrawal reflex happens in our leg, we need

A

the other leg to extend to keep us upright

14
Q

The excitatory interneurons which cross the spinal column cause ___ while ___

A

the extensor muscles to contract

while other interneurons inhibit the contralateral flexors