PSL300 Final Exam Prep Questions
With Complete Solutions
Simple Reflexes correct answer: Sensory neurons make
synapses with spinal cord motoneurons to mediate simple
reflexes. This is the simplest form of motor control
Central Pattern Generators correct answer: Networks of
interneurons in the spinal cord and brainstem coordinate the
interactions of many groups of motor groups. Works for things
such as breathing, flying, etc. Produces a rhythmic pattern
output.
Complex / Volitional Movement correct answer: Motor output
that is planned and refined by the motor cortex, basal ganglia,
and cerebellum.
Reflexes (bending back) correct answer: Sensory stimuli comes
to CNS to produce a motor response. This performs a specific
task, often a feedback loop regulating force, position, etc.
Reflex Loop correct answer: 1. Sensory specific stimulus
2. Sensory afferent brings it into the CNS
3. Motor efferent brings it back out
4. Response
Can be monosynaptic or polysynaptic.
Stretch Reflex correct answer: You stretch it, it will contract.
Operates at the subconscious level. Very sensitive and fast.
,Stimulus = passive stretch of the muscles.
Response = active flex of the muscle.
Essential for maintaining posture (extensor muscles) +
stabilizing joints. Works in 25ms for forearm, and 37ms in the
ankle extensors. Goes up to the medial somatosensory cortex as
well even though it is a simple reflex. Can be suppressed during
movement.
Golgi Tendon Reflex correct answer: You contract it, it will
relax. GTO afferents synapse on interneurons in immediate zone
of spinal cord. Interneurons inhibit motor neurons of the same
muscle.
Stimulus = active tension of the muscle
Response = relaxation or reduction of tension
This is a polysynaptic reflex. It is the opposite of the stretch
reflex and works to inhibit overexertion.
Flexion Withdrawal Reflex correct answer: You touch a hot
stove, you flex your arm.
Stimulus = noxious injury of limb
Response = flexion of joints proximal to stimulus, extension of
distal joints (ex. drop your phone after burning forearm).
Nociceptor afferents synapse on interneurons in superficial
dorsal horn - slowly conductive afferents. Multi-synaptic path to
motor neurons.
Reciprocal Inhibition correct answer: Activation of one motor
nucleus is coupled to inhibition of antagonistic motor nucleus.
Joint movement would be very difficult without this.
, Patellar Tendon Reflex correct answer: You bang your knee,
you kick.
Stimulus = tap of patellar tendon
Response = stretch quads, inhibit hamstrings
Cross Extension Reflex correct answer: You step on something
sharp, flex your leg where there is pain and extend the other leg.
Involves contralateral extension for increased postural support.
Commissural neurons send signal to contralateral spinal cord.
Only works in the legs for normal people, gymnasts might have
arms too
Extensor Thrust Reflex correct answer: Stimulus = pressure on
sole of foot (innocuous)
Response = activation of leg extensors
Mechanoreceptors project to immediate zone interneurons ->
extensor motoneurons.
Reflex operates only during stance (helps keep you up).
Babinski sign correct answer: Extensor thrust reflex is
influenced by corticospinal tract. Can be elicited at rest in the
toes by stroking of the foot. If corticospinal tract is damaged,
reflex pattern is switched to withdrawal (flexion) rather than
antigravity pattern.
Vestibulo-spinal reflex correct answer: Stimulus = downward
deviation of head on one side, activates otolith afferents.
Response = downhill limbs extended
Otolith afferents activate lateral vestibulo-spinal tract: ipsilateral
(same side) projection to extensor (antigravity) motor nuclei.
Postural latency = 80ms in legs
With Complete Solutions
Simple Reflexes correct answer: Sensory neurons make
synapses with spinal cord motoneurons to mediate simple
reflexes. This is the simplest form of motor control
Central Pattern Generators correct answer: Networks of
interneurons in the spinal cord and brainstem coordinate the
interactions of many groups of motor groups. Works for things
such as breathing, flying, etc. Produces a rhythmic pattern
output.
Complex / Volitional Movement correct answer: Motor output
that is planned and refined by the motor cortex, basal ganglia,
and cerebellum.
Reflexes (bending back) correct answer: Sensory stimuli comes
to CNS to produce a motor response. This performs a specific
task, often a feedback loop regulating force, position, etc.
Reflex Loop correct answer: 1. Sensory specific stimulus
2. Sensory afferent brings it into the CNS
3. Motor efferent brings it back out
4. Response
Can be monosynaptic or polysynaptic.
Stretch Reflex correct answer: You stretch it, it will contract.
Operates at the subconscious level. Very sensitive and fast.
,Stimulus = passive stretch of the muscles.
Response = active flex of the muscle.
Essential for maintaining posture (extensor muscles) +
stabilizing joints. Works in 25ms for forearm, and 37ms in the
ankle extensors. Goes up to the medial somatosensory cortex as
well even though it is a simple reflex. Can be suppressed during
movement.
Golgi Tendon Reflex correct answer: You contract it, it will
relax. GTO afferents synapse on interneurons in immediate zone
of spinal cord. Interneurons inhibit motor neurons of the same
muscle.
Stimulus = active tension of the muscle
Response = relaxation or reduction of tension
This is a polysynaptic reflex. It is the opposite of the stretch
reflex and works to inhibit overexertion.
Flexion Withdrawal Reflex correct answer: You touch a hot
stove, you flex your arm.
Stimulus = noxious injury of limb
Response = flexion of joints proximal to stimulus, extension of
distal joints (ex. drop your phone after burning forearm).
Nociceptor afferents synapse on interneurons in superficial
dorsal horn - slowly conductive afferents. Multi-synaptic path to
motor neurons.
Reciprocal Inhibition correct answer: Activation of one motor
nucleus is coupled to inhibition of antagonistic motor nucleus.
Joint movement would be very difficult without this.
, Patellar Tendon Reflex correct answer: You bang your knee,
you kick.
Stimulus = tap of patellar tendon
Response = stretch quads, inhibit hamstrings
Cross Extension Reflex correct answer: You step on something
sharp, flex your leg where there is pain and extend the other leg.
Involves contralateral extension for increased postural support.
Commissural neurons send signal to contralateral spinal cord.
Only works in the legs for normal people, gymnasts might have
arms too
Extensor Thrust Reflex correct answer: Stimulus = pressure on
sole of foot (innocuous)
Response = activation of leg extensors
Mechanoreceptors project to immediate zone interneurons ->
extensor motoneurons.
Reflex operates only during stance (helps keep you up).
Babinski sign correct answer: Extensor thrust reflex is
influenced by corticospinal tract. Can be elicited at rest in the
toes by stroking of the foot. If corticospinal tract is damaged,
reflex pattern is switched to withdrawal (flexion) rather than
antigravity pattern.
Vestibulo-spinal reflex correct answer: Stimulus = downward
deviation of head on one side, activates otolith afferents.
Response = downhill limbs extended
Otolith afferents activate lateral vestibulo-spinal tract: ipsilateral
(same side) projection to extensor (antigravity) motor nuclei.
Postural latency = 80ms in legs
