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Flashcards in Reflexes Deck (14):

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

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


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

Alpha motoneurones

agonist muscle to contract

a monosynaptic reflex


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

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


What is the reflex mediated by the Golgi tendon organs?

Inverse stretch/clasp-knife reflex


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

increase their discharge


Increased discharge from the Golgi tendon bodies activates ___ and ___

inhibitory interneurons to the agonist muscle

decreases the contraction strength


Increased discharge from the Golgi tendon organs also

activates excitatory interneurons to the antagonistic muscle


The inverse stretch reflex is ___

It ___

polysynaptic and protective

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


What does the flexor-withdrawal reflex use?

information from the nociceptors in skin, muscle and joints


Flexor-withdrawal reflexes are

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


Sensory stimulus causes

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


Inhibitory neurones work on

antagonistic extensors


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

the other leg to extend to keep us upright


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

the extensor muscles to contract

while other interneurons inhibit the contralateral flexors