L-23

Question 1

What are three differences between reflex and voluntary movements?

Answer 1

• Reflex are rapid, reproducible, automatic responses to stimuli, voluntary are a wide variety of movements or varying speed duration and complexity
• Reflex employ simple neural circuit involving only the PNS and the spinal chord, Voluntary involves complex patterns of sensory and motor complexes in brain
• reflex does not require involvement of higher brain centres, voluntary is initiated in brain and involve many brain centres

Question 2

What is a stretch reflex?

Answer 2

An involuntary response to a external stretch stimulus that results in contraction of the muscle effectors

Question 3

Explain the process of a stretch reflex:

Answer 3

• stimulus triggers an AP in sensory neuron that travels to CNS in spinal chord. Information is processed and an AP is triggered in a motor neuron resulting in muscle contraction to counter the stretch

Question 4

What is a withdrawal reflex?

Answer 4

An involuntary response to a painful or potentially harmful stimulus

Question 5

Explain the process of a withdrawal reflex:

Answer 5

• receptors are stimulated and trigger an AP that travels up axon of sensory neuron to CNS in spinal chord. Information is processed there and an AP is sent down a motor neuron to trigger a response the moves the affected body part away from the stimulus

Question 6

What is the role of the cerebellum in the brain? (4)

Answer 6

• helps plan, execute and learn motor programs
• integrates sensory info with planned events
• recieves information from the proprioceptive sensory neurons
• compares result of planned movements with actual result and adjusts accordingly

Question 7

What is Ataxia?

Answer 7

Movement disorders likely caused by issues in the cerebellum

Question 8

What forms of ataxia can be caused by disorders of the cerebellum?

Answer 8

• “drunken gait”
• tremor
• dysarthria- speech disorder do to breathing issue
• dysmetria - disorder related to distance judgement

Question 9

What are the steps of planning and executing a movement? (5)

Answer 9

• decision is made in frontal lobe
• Basal nuclei adjust patterns of movement
• cerebellum monitors balance and equilibrium and adjusts upper motor neurons activity
• motor cortex controls how much force produced during a movement
• sensory feedback needed and utilised to match the actin to the intention

Question 10

What does the frontal lobe take into account when making a decision for a movement? (6)

Answer 10

• intentions
• memories + experiences
• risk
• personality
• emotion
• environment

Question 11

What are the two ways that basal nuclei adjust patterns of movement?

Answer 11

• by altering sensitivity of pyramidal cells to adjust output along the corticospinal tract
• by changing the excitory or inhibitory output of the medial and lateral pathways

Question 12

How does the motor cortex control the amount of force produced by a movement?

Answer 12

• by controlling how many motoneurons (motor units) are activated and by the frequency of action potential firing