Reflexes Flashcards
Describe the stretch reflex
After a short tap to inelastic tendons
force is transmitted to muscle fibres which stretch
Stretch activates sensory nerves in muscle spindle which increases frequency of APs in afferent/sensory nerves.
Alpha motor neurons activate and agonist muscle contracts
Alpha neurons are inhibited to antagonist muscle which relaxes
Describe the reflex mediated by the golgi tendon organ…
Known as the inverse stretch or clasp-knife reflex…
As the muscle contracts, it pulls on the tendons and the Golgi tendon bodies increase their discharge.
This activates inhibitory interneurons to the agonist muscle and decreases the contraction strength, while also activating excitatory interneurons to the antagonistic muscle.
What type of reflex is the golgi/clasp-knife reflex and whats its purpose?
This reflex is polysynaptic and protective. It prevents over contraction and prevents the muscle from tearing the tendon insertion points away from the bones.
What type of receptors does the flexor-withdrawal
Nocieceptors
Function of flexor-withdrawal? Poly or monosynaptic?
Polysynaptic - withdraw the affected part of the body away from the often harmful stimulus and towards the body.
Describe the flexor withdrawal reflex
Sensory stimulus causes an increase in activity of flexor muscles via a number of excitatory interneurons
Inhibitory neurones work on the antagonistic extensors.
Is an ipsilateral flexion response to pain
During flexor-withdrawal, say the reflex is in the leg and you move it fast and do nothing else - you would fall - what stops this?
Contralateral extensors
Describe the whole contralateral thing
During the flex-withdrawal reflex;
Several excitatory interneurones cross the spinal cord and excite the contralateral extensors
At the same time, via several interneurones, there is inhibition of the contralateral flexors
Helping maintain upright posture by one leg flexing to withdraw from pianful stimulus and the other leg extending to maintain balance
