Chapter 8: Movement

Question 1

Muscles

Answer 1

Composed of fibers; each fiber is innervated by one motor neuron

Question 2

Smooth muscle

Answer 2

internal organs, long, thin cells

Question 3

Skeletal/striated muscle

Answer 3

main movers, long cylindrical fibers with stripes

Question 4

cardiac muscle

Answer 4

heart; fused fibers contract together

Question 5

Motor Unit

Answer 5

smallest functional unit

Question 6

Neuron meets fiber at ?

Answer 6

Neuromuscular junction

Question 7

Antagonistic muscles work in concert

Answer 7

Flexors vs Extensors

Question 8

Myasthenia Gravis

Answer 8

autoimmune disorder; antibodies against ACh receptors

Question 9

Symptoms of Myasthenia Gravis

Answer 9

progressive weakness, rapid fatigue of skeletal muscles

Question 10

Physiological Basis of Myasthenia Gravis

Answer 10

fewer ACh receptors, morphological changes at synapse, action of Acetycholinsterase

Question 11

Mammalian Muscles

Answer 11

Fast-twitch fibers and slow-twitch fibers

Question 12

Fast-twitch fibers

Answer 12

contract and relax rapidly, anaerobic (no oxygen), fatigue rapidly, generate greatest force, (ex sprinting)

Question 13

Slow-twitch fibers

Answer 13

longer contraction time, aerobic (oxygen), resistant to fatigue, generate much less force (walking)

Question 14

Proprioceptors

Answer 14

Sensitive to position and movement of muscles; detect muscular stretch and tension; allows spinal cord to adjust signal

Question 15

Two primary types of proprioceptors

Answer 15

Muscle spindles and golgi tendon organs

Question 16

Muscle Spindles

Answer 16

parallel to muscle, senses stetch; muscle stretched -> signal motor neuron in spinal cord –> muscle contraction; negative feedback –> stretch causes contraction; stimulates Stretch reflex (knee-jerk)

Question 17

Golgi Tendon organs

Answer 17

in tendons (connects muscles to bone), senses tension; vigorous muscle contraction –> signal spinal cord inhibitory interneurons –> inhibit motor neuron (inhibits contraction); negative feedback –> tension causes muscle relaxation; protects against vigorous contraction

Question 18

Reflexes

Answer 18

consistent, automatic response to stimulu; allied reflexes occur together/ elicit each other

Question 19

Ballistic movements

Answer 19

executed as a whole; cannot be corrected/not sensitive to feedback

Question 20

Central Pattern Generators

Answer 20

neural mechanisms that generate rhythmic motor patters (wet dog shake, wing flapping in birds)

Question 21

Major motor areas in FOREBRAIN

Answer 21

Cortex, basal ganglia

Question 22

Major motor areas in MIDBRAIN

Answer 22

Substantia Nigra; Red Nucleus; Reticular Formation

Question 23

Major motor areas in HINDBRAIN

Answer 23

Cerebellum, Reticular formation, vestibular nucleus

Question 24

Primary Motor Cortex

Answer 24

coordinated movements in several muscles leading to specific outcome

Question 25

Posterior Parietal Cortex

Answer 25

coordinating movement through environment based on visual input

Question 26

prefrontal cortex

Answer 26

involved in planning movement

Question 27

premotor cortex

Answer 27

involved in planning movement

Question 28

supplementary cortex

Answer 28

involved in preparation for rapid sequences of movement

Question 29

Dorsolateral Tract

Answer 29

carries axons from primary motor cortex and red nucleus to spinal interneurons controlling spinal motor neurons; THEN cross over to contralateral side at pyramids in ventral portion; THEN courses down dorsolateral portion of white matter of spinal cord; THEN controls movement of distal limbs (hands,fingers,toes)

Question 30

Ventromedial Tract

Answer 30

Carries axons from primary motor cortex, axons from vestibular nucleus, tectum, reticular formation; THEN synapse on spinal interneurons controlling spinal motor neurons; THEN come axons cross, some dont, providing bilateral innervation; THEN courses down ventromedial portion of white matter of spinal cord; controls proximal limbs and axial musculature (neck, shoulders, trunk)

Question 31

Motor functions of cerebellum

Answer 31

contains more neurons than rest of structures of brain combined; involved in: control of rapid eye movement, timing, establishment of new motor programs

Question 32

Caudate Nucleus

Answer 32

primary input area; receives info from sensory areas of thalamus and cortex; receives important dopaminergic projection from substantia nigra in midbrain

Question 33

putamen

Answer 33

same function

Question 34

globus pallidus

Answer 34

primary output area; sends info to thalamus, which sends info to motor and prefrontal cortex, also midbrain

Question 35

role of basal ganglia

Answer 35

organization of action sequences into chunks; inhibition of specific motor responses

Question 36

Parkinson's disease

Answer 36

degeneration of the dopaminergic neurons in the substantia nigra projecting to the caudate nucleus and putamen

Question 37

symptoms of parkinson's disease

Answer 37

rigidity; muscle tremors; slow movements; sometimes cognitive deficits; difficulty initiating movement; sometimes depression

Question 38

frequency of parkinson's disease

Answer 38

1/100 above age 50

Question 39

Causes of Parkinson's disease

Answer 39

early onset has genetic component; possible environmental influence

Question 40

Treatment for Parkinson's disease

Answer 40

L-dopa: crosses blood-brain barrier, where its absorbed by neurons and can increase dopamine production; cant restore degenerated neurons; effectiveness declines as disease progresses

Question 41

Other possible treaments

Answer 41

Antioxidant drugs - decrease further damage; dopaminergic agonists - can cross blood-brain barrier; glutamate or adenosine antagonists; inactivating electrical stimulation of globus pallidus; neurotrophins - promote growth and survival of neurons; drugs that decrease apoptosis; fetal tissue transplants; drugs that block calcium channels abundant in elderly brains; drugs that stimulate cannabinoid receptors