Reflexes Flashcards
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
