Reflexes Flashcards
What is the stretch reflex?
Sharp tap applied to tendons which are inelastic. Force transmitted to muscle fibres which stretch. Sensory nerves in muscle spindles activated. Increased number of AP’s. Afferent nerves project into spinal cord via dorsal horn.
What happens when spindles are stimulated?
Alpha-motoneurones are activated and the agonist muscle contracts. Antagonist therefore relaxes.
What is the golgi tendon reflex?
Caused by afferent nerves from GTO’s which monitor muscle tension. Inhibitory interneurones activated in agonist muscle which decreases strength of contraction. Activation of excitory interneurones to antagonist muscles. Information about muscle tension ascends in the dorsal columns to the somatosensory cortex.
Why is the golgi tendon reflex protective?
It prevents over contraction and prevents the muscle tearing from the tendon.
What is the flexor withdrawal reflex?
Polysynaptic and protective. Protects the body from damaging stimuli by using nociceptors in the skin, muscles and joints. Part of the body moved away from the painful stimulus in towards the body - it is flexed. Increased sensory AP’s and increased activity in flexors via excitory interneurones. Antagonistic receptors are inhibited.
What does sensory stimulus cause in the flexor reflex?
Increased activity of flexor muscles via excitory interneurones. Inhibitory interneurones work on the antagonistic extensors.
What is the only monosynaptic connection in the body?
Stretch reflex. Alpha-motoneurones cause rapid contraction of the agonist muscle without interneuron involvement.
What is the difference between ipsilateral and contralateral reflexes?
Ipsilateral occur on the same side of the body that is stimulated. Contralateral occurs on the opposite side.
Where does information about muscle tension go in golgi tendon reflex?
Afferent somatosensory neurones ascend to the dorsal columns of the CNS.
Is the flexor reflex ipsilateral or contralateral?
Ipsilateral.
Where does information about pain ascend?
Contralateral dorsal tracts. Excitory interneurones cross the spinal cord and excite contralateral extensors. Contralateral flexors are inhibited.
What is likely if there are no reflexes in a co-operative patient?
Peripheral nerve damage.
What happens if gamma-motoneurone discharge to muscle is increased?
Muscle becomes extremely resistant to stretch and is said to be spastic. A lot of neurological disorders are associated with this.
