Reflexes Flashcards
Define reflex
Involuntary movement/action to a stimulus
What is the plantar/ babinski reflex why do Babies who it
stroking of the outer side of a baby’s foot causes the toes to spread in an upward movement
myelination of their spinal cord tracts is not complete
2 types of reflexes
somatic and autonmic
5 components of a reflex arc
. receptor
- sensory neuron
- integration centre - either mono (sensory neuron interfacing straight up w. a motor via one synapse) or poly synaptic (sensory inter neuron motor neuron 2 or more synapses BTW interneurons only in CNS) region within CNS
- motor neuron
- effector - muscle fibre, gland etc.
Why is testing reflexes important and what are the most commonly assesses ones
May indicate some sort of degenerations of a specific nervous system region
Stretch and tendon
Flexor / cross- extensor
Superficial
Ocular
function of stretch and tendon reflex
smooth ordination of skeletal muscle
provide NS w propriosetive information to regulate joint position and movement in space- 2 types of information
length of muscles by muscle spindles
amount of tension within muscle sent from the Golgi tendon organs (TGOs) poly synaptic
2 types of afferent endings in muscle spindles
Anulospiral - wrap around spindle, stimulate by rate and degree of stretch
Flower spray endings - small axons at ends of spindle only stimulated by degree of stretch
What helps support the innovated muscle spindle endings
Gamma efferent fibres help maintain sensitivity
What does stretching the muscle do
Activates muscle spindles sensory fibres detect and more action potentials are generated
Purpose of alpha gamma coactivation and how it works
No stretching spindles and sensory endings generate no action potential so no sensory info to NS about the muscle.
so gamma and alpha (sensory neurons) innervate extrafusal and intrafusal muscle fibres at same time so some tension and therefore AP is maintained
what happens when a muscle stretches
Muscle spindles activate and sensory neurons send a message to spinal cord
what is reciprocal inhibition
when an antagonist muscle eg quad and hammie is reduced to help the other muscle oppose the stretch
Q FOR L what are gamma and Alpha motor / sensory neurons why are they important
…
what nervous tissue does the Patella knee jerk reflex assess
between and including L2 and L4 segments of SC
What. happens after a muscle is stretched
The sensory neurons form a monosynaptic connecting with alpha motor Hurons which tell the muscle to interact at same time poly synaptic connection with interneurons that tell the antagonist muscle to relax (inhibit it) so it doesn’t resist the contraction of the other
purpose of tendon reflexes and by what are they initiated
is it mono or poly synaptic reflex
prevent muscles from tearing due to excessive forces
initiated by Golgi tendon organs or GTOs (force sensors)
poly synaptic
how does tendon reflexes work
contraction or passive stretch activates reflex, afferent impulses to SC, contracting muscle relaxes. antagonist muscle contracts (reciprocal activation)
what is the flexor reflex stimulated by
why important
mono or poly synaptic
initiated by a painful stimulus
poly synaptic and ipsilateral
importnat for survival
what is crossed extensor reflex
occurs the flexor reflex to maintain balance, eg. stepping on glass with right foot the reflex stimulates the eft to contract and maintain its balance while the right foot is pulled away
contralateral extensor reflex
INVOLVES FLEXOR REFLEX
what is the h reflex and why is it measured in the specific way it is by researchers
basically the stretch reflex but stimulated through a electrical shock to the nerve rather than through the muscle to avoid testing the functionality of the muscle spindles but rather focus on the ability of the neurons
two ocular reflexes
pupillary light - diameter of pupil in response to light
vesibulo-ocular reflex
what is the vesibulo - ocular reflex
controls eye movement when the head moves equal and opposite to movement of the head so that images are continuously centred and within field of vision
fastest reflex in body at 5 mili seconds
tested by turning head really quickly
what does plantar reflex test
tests integrity of spinal cord from L4 to S2
response in adults should be downward flexion of toes
2 types of reflexes
somatic (skeletal muscle)
autonomic (smooth muscle, glands, cardiac muscle)
2 sensory tools that aid stretch and tendon reflex
muscle spindles
Golgi tendon organs
anatomy of muscle spindles
3-10 skeletal muscle fibres INTRAFUSAL and within a capsule
gamma effect fibres at end (intrafusal)
muscle fibres (extrafusal) innervated by alpha motor neurons
what is mono and what is polysynaptic in knee jerk reflex
quadricep inhibition (stop stretching) is monosynaptic inhibition of hamstring is poly
RECIPROCAL INHIBITION
stretch vs tendon reflex
stretch - contraction of stretched (mono), inhibition of antagonist (poly), initiated by muscle spindles, reciprocal inhibition, both poly and monosynaptic
tendon - relaxation of flexed, activation of antagonist, tearing due to excessive force, ignited by GTO, polysynaptic reflex, reciprocal activation
