CHAPTER 11 : MOTOR CONTROL PART 1

Question 1

Reflex

Answer 1

simple, unvarying, unlearned response to sensory stimuli such as touch, pressure, and pain

Question 2

Motor Plan

Answer 2

set of muscle commands established before an action occurs

Question 3

Closed - loop mechanisms

Answer 3

• maximizes accuracy
• information from what is being controlled flows back to the controlling device

Question 4

open-loop mechanisms

Answer 4

• maximize speed
• no external feedback; the activity is pre-programmed

Question 5

The Motor System

Answer 5

• all the muscles
• all the neurons that control the muscles
• purpose is to generate coordinated movements

Question 6

Spinal Cord

Answer 6

contains pre - wired motor programs for coordinated muscle contractions

Question 7

brain / motor cortex

Answer 7

initiates and controls
motor programs

Question 8

Synergists (agonists)

Answer 8

muscles that act together, providing more total force

Question 9

antagonists

Answer 9

muscles whose contraction causes movement in opposite directions

Question 10

How do muscles move?

Answer 10

By contracting / becoming shorter

Question 11

Motor Neurons

Answer 11

Carry the signals from the brain to move muscles

Question 12

Alpha Motor Neurons

Answer 12

• Final neurons that carry the message from the spinal cord to the muscles
• control muscle contraction
• contain A - alpha axons and are large and fast

Question 13

What happens when an alpha motor neuron fires an AP?

Answer 13

• ACh is released into the Neuromuscular junction
• causes a strong depolarization of that the muscle fiber contracts

Question 14

Neuromuscular Junction

Answer 14

Connection between the alpha motor neuron and the muscle fiber

Question 15

Motor Unit

Answer 15

• One motor neuron and all the muscle fibers it stimulates
• helps with fine precision

Question 16

Motor Neuron Pool

Answer 16

• all the motor neurons that stimulate a single muscle

Question 17

what does the motor neuron release?

Answer 17

• ACh
• binds to nicotinic receptors and opens ion channels
• depolarizes muscle cells
• depolarization releases Ca2+ stored inside muscle fiber and causes the fiber to contract

Question 18

Myasthenis gravis

Answer 18

• autoimmune disease
• attacks nicotinic receptors, causes muscle weakness

Question 19

Actin and Myosin

Answer 19

• filaments
• give muscle striated appearance
• increasing amount of overlap between filaments causes contractions

Question 20

Fast - twitch fibers

Answer 20

• quick and accurate
• white
• can not maintain tension for long

Question 21

Slow - twitch fibers

Answer 21

• slower to respond
  -red
• more resistent to fatigue

Question 22

Proprioception

Answer 22

• sense of body movements and position
• critical for coordinating and adjusting movement rapidly
• uses large, myelinated axons
• uses muscle spindles and golgi tendon organs

Question 23

Golgi tendon organ

Answer 23

• detect changes in muscle tension with nerve endings in tendons; sends signals to spinal cord on A-Beta fibers
• can inhibit motor neurons to reduce tension

Question 24

muscle spindle

Answer 24

• detect changes in muscle stretch / length using fibers that wrap around muscle fibers
• primary endings signal muscle stretch
• secondary endings signal muscle length

Question 25

Skeletal System

Answer 25

allow for movement

Question 26

Spinal Cord

Answer 26

controls skeletal muscles

Question 27

Brainstem

Answer 27

relays sensory information and integrates motor commands

Question 28

Primary Motor Cortex

Answer 28

initiates commands for action

Question 29

Non - primary motor cortices

Answer 29

provides additonal source for motor commands

Question 30

Cerebellum and Basal Ganglia

Answer 30

modulate activities of control systems

Question 31

hierarchy of motor control systems

Answer 31

• Motor Cortex
• Basal Ganglia, Thalamus, or Cerebellum
• Brainstem
• Spinal Cord
• Muscles of body