reflex arcs Flashcards
what are the components of the simple monosynaptic reflex arc
- sensory organ (stretch receptor in muscle spindle)
- transmission (1a sensory fibre)
- processing (synapse in grey matter of spinal segment)
- transmission (motor neuron)
- action (muscle)
Brain does not need to be involved - the muscle senses the lengthenin and reacts)
- allows for rapid response to changes in muscle positions
what is the difference between a monosynaptic and polysnynaptic reflex arc
mono = one synapse
poly= more than one synapse
describe the structure and function of the muscle spindle
a muscle spindle is the sensory organ of the muscle
what is the function of the golgi tendon organ
- sits within the tendon and measures tension in the tendon (t;f muscle)
- located serial to muscle fibres
- strain gauges
- can produce reverse myotatic reflex
- involved in clasp knife refelx (protective mechanism causing release if there is an overload of tension)
what is schiff sherrington syndrome
- inability to move hindlimbs due to spinal cord injury, but when there is hypertonicity in the forelimbs (move stiff and rigid)
- reflex with interneurons connecting the pelvic and cervical intumescences (RF moves forward causing LH to respond)
bad sign. wont see unless there is damage to spinal cord
what happens when there is a lesion in the upper motor neurons
- absent voluntary motor
- spastic paralysis
- hyper/normoflexia
- slow muscle wastage
what is a reflex arc
- the simple organisation within the nervous system
- mechanism for action and reaction
- automation of actions
what spinal nerves are involved in thoraic limb outflow
- C6
- C7
- C8
- T1
what happens when there is a lesion to the lower motor neuron
- absent voluntary motor
- flaccid paralysis
- hypo/areflexia
- rapid muscle wastage
what spinal nerves are involved in pelvic limb outflow
- L4
- L5
- L6
- L7
- S1
- S2
- S3
