Reflexes

Question 1

What is a stretch reflex?

Answer 1

It is monosynaptic reflex found in all muscles

Question 2

What causes a stretch reflex?

Answer 2

A sharp tap to the tendons (which are inelastic) which transfers the force to muscle fibres which stretch and stimulate the spindles

Question 3

What is the process of the stretch reflex?

Answer 3

Alpha motor neurones are activated and the agonist muscle contracts. The antagonist muscle relaxes as the spindle activates inhibitory interneurones which decreases alpha motor neurones to the antagonists

Question 4

What is an example of a stretch reflex?

Answer 4

Knee jerk

Question 5

Can the stretch reflex be overridden?

Answer 5

Yes, if what is being held is of importance due to descending voluntary excitation of alpha motor neurones

Question 6

What is a GTO mediated reflex?

Answer 6

A polysynaptic reflex which is a result of muscles contracting and pulling on the tendons which increased GT bodies discharge.

Question 7

What type of interneurone are activated to agonist muscles in GTO mediated reflexes?

Answer 7

Inhibitory (causing contraction)

Question 8

What type of interneurone are activated to antagonist muscles in GTO mediated reflexes?

Answer 8

Excitatory

Question 9

What is an example of a GTO mediated reflex?

Answer 9

Clasp-knife reflex

Question 10

Why are GTO mediated reflexes protective?

Answer 10

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

Question 11

Can GTO mediated reflexes be overridden?

Answer 11

Yes

Question 12

Where are interneurones involved?

Answer 12

Polysynaptic reflexes

Question 13

What is the function of interneurone?

Answer 13

They allow a different response from the same sensory information

Question 14

What type of muscle do interneurones act?

Answer 14

Antagonistic

Question 15

What is reciprocal inhibition?

Answer 15

When an agonist contracts the antagonists stretches which causes activation of inhibitory interneurone which decrease the activation of alpha motor neurones to the antagonist which then relaxes

Question 16

What are the 2 types of reflexes?

Answer 16

Ipsilateral (same side) and contralateral (opposite side)

Question 17

What is the flexor-withdrawal reflex?

Answer 17

It is a polysynaptic reflex that uses information from the nociceptors in skin, muscles and joints and withdraws the body part affected by stimulus

Question 18

What is the process by which flexor-wirhdrwal reflexes operate?

Answer 18

Sensory stimulus causes an increase in agonist flexor muscles via excitatory interneurones, while inhibitory neurones work on antagonists extensors. If this happens on one leg, then the other leg has to take the strain

Question 19

How can contralateral muscles exchange strain?

Answer 19

Excitatory interneurones which cross the spinal column cause the extensor muscles to contract while the other interneurones inhibit contralateral flexors

Question 20

What happens as the pain stimulus is increased?

Answer 20

The spinal spread increases which causes a larger response so more alpha motor neurones are engaged

Question 21

How is stimulus increased?

Answer 21

Facilitation

Question 22

What do pain fibres facilitate?

Answer 22

The action of muscle spindles by maintaining the alpha motor neurones in a more depolarised state