Spinal Cord and Reflexes Flashcards
What mediates and activates autonomic reflexes?
mediate - autonomic nervous system
activate - smooth muscle, cardiac muscle and glands
What mediates and activates somatic reflexes?
Mediate - somatic nervous system
Activate - stimulation of skeletal muscle
What are the 3 steps of the monosynaptic reflex arc?
1) sensory input
2) information processing
3) motor output
What are the 5 components of the monosynaptic reflex arc?
1) receptor
2) sensory neurone to CNS
3) interpretation centre
4) motor neurone away from CNS
5) Effector muscle contracts or gland secretes
What are the epineurium, perineurium and endoneurium?
epineurium surrounds whole peripheral nerve
perineurium surrounds bundles within
endoneurium surrounds individual nerves
What is a polysynaptic reflex?
More than one synapse which makes it slower
5 steps in the muscle spindle reflex?
1) extrafusal muscle fibres at resting length
2) sensory neurons are tonically active
3) spinal cord integrates function
4) alpha motor neurons to extrafusal fibres receive tonic input from muscle spindles
5) extrafusal fibres maintain a certain level of tension even at rest
What are the 4 stages in alpha gamma coactivation?
1) afferent input from sensory endings of muscle spindle fibre
2) alpha motor neuron output to regulate skeletal muscle fibre
3) gamma motor neuron output to contractile portions of spinel fibre
4) descending pathways coactivate alpha and gamma motor neurons
What is the cross cord reflex?
this is where the contralateral limb compensates for loss of support when the ipsilateral limb withdraws from a painful stimulus in a withdrawal reflex
What is ipsilateral?
reflex occurs on the same side of the body as the stimulus
What is contralateral?
reflex occurs on the opposite side of the body from the stimulus
What are central pattern generators?
They are neural circuits which produce rhythmic outputs in the absence of rhythmic input
What are Renshaw cells?
They are inhibitory interneurons found in the grey matter of the spinal cord and are associated in two ways with an alpha motor neuron
it can block the neurone from being further excited
What are the two pyramidals involved in descending control?
Corticospinal and corticobulbar
What are the 4 extrapyramidals involved in descending control?
Vestibulospinal (Vestibular nucleus, lateral VS, medial VS)
tectospinal, reticulospinal and rubrospinal
