Reflexes

Question 1

What is the role of interneurons?

Answer 1

To transmit impulses between neurons as part of a reflex arc.

Question 2

Describe the stretch reflex.

Answer 2

Sharp tap to inelastic tendon
Force is transmitted to muscle fibres which are more able to stretch
This stretch activates sensory nerves of the muscle spindle
Afferent neurons from the spindle activate the alpha motor neuron pool of the muscle which was stretched, causing rapid contraction of agonist.
(NB: afferent neurons of the spindle also connect with inhibitory interneurons which decrease activation of the alpha motor neurons to the antagonistic muscle, causing it to relax)
So this is an example of negative feedback.

Question 3

What is the only monosynaptic reflex known and what is meant by this?

Answer 3

Stretch reflex

Contains no interneurons

Question 4

What is the role of the Golgi tendon organ reflex?

Answer 4

It is protective

Prevents muscle contracting so much that tendon pulls away from bone.

Question 5

Describe the mechanism of the GTO reflex.

Answer 5

Muscle contracts, increasing tension on tendon
1b Sensory nerves from GTO increase firing of Action Potentials
This causes:
1. Activation of inhibitory interneurons to the agonist muscle to decrease muscle contraction strength.
2. Activation of excitatory interneurons to antagonist muscle, so that this muscle contracts