Chapter 8: Movement

Question 1

smooth vs striated muscle

Answer 1

smooth: found in the lining of the digestive tract, within arteries, and in the reproductive system, controlled by the autonomic nervous system
striated muscle: cardiac muscle (found in the heart), skeletal muscle (attached to bones), responsible for the majority of body movements

Question 2

what is the anatomy of the muscle?

Answer 2

the interior of the muscle fiber is made up of long strands of protein called myofibrils, a single segment of a myofibril is a sarcomere, the Z line is the boundary of each sarcomere, filaments of proteins actin and myosin lie on each Z line, thick myosin filaments and thin actin filaments work together to generate muscle contractions and movement

Question 3

what are the three types of muscle fibers and what do they do?

Answer 3

Type 1: slow twitch, long distance, less fatigue
Type 2A: fast twitch, oxidative, moderate distance and fatigue
Type 2B: fast twitch, glycolytic, short distance, high intensity, high fatigue

Question 4

what does lack of activity cause in the muscle?

Answer 4

lack of activity leads to a reduction in myosin and actin produced, filament proteins are either broken down faster or synthesized more slowly when muscles are not used

Question 5

what are alpha motor neurons?

Answer 5

spinal motor neurons responsible for contracting muscles, capable of rapid firing

Question 6

what is the neuromuscular junction?

Answer 6

where alpha motor neurons meet muscle fibers

Question 7

what is the motor unit?

Answer 7

made up of a single alpha motor neuron and all the muscle fibers it innervates, can include fast- or slow-twitch fibers but not a mixture of both

Question 8

which three neurons provide feedback to the alpha motor neurons and what do they do?

Answer 8

1. muscle spindle: specialized sensors that help to form the feedback loop from muscle fiber to spinal cord; muscle length
2. golgi tendon organs: provide feedback about degree of muscle contraction
3. joints: provide information about position and movement from mechanoreceptors in tissue around each joint

Question 9

what is the myotatic reflex?

Answer 9

contraction in response to sensing
stretch

Question 10

how does the patellar reflex work?

Answer 10

hammer tapping knee stretches the quad muscle, sensory fibers in muscle spindles detect stretch which stimulates alpha motor neurons in the spinal cord which cause quad to contract

Question 11

what is an example of feedback from a golgi tendon organ?

Answer 11

golgi tendon organs are located between muscle and tendon where it detects contraction and relays info to spinal interneuron which inhibits alpha motor neuron, relaxing the muscle

Question 12

what is an example of feedback from a joint?

Answer 12

reciprocal inhibition occurs at joints, each joint has at least one pair of antagonistic muscles (flexor and extensor), contraction of biceps flexes elbow and tricep extends the joint

Question 13

what is the flexor reflex?

Answer 13

protection from further injury when sensory neurons perceive pain (touching a hot stove)

Question 14

lateral vs ventromedial pathways?

Answer 14

lateral: originates in the cerebral cortex, voluntary movements
ventromedial: originates in brainstem, subconscious, automatic movements of the neck and torso

Question 15

what does the cerebellum do in regards to movement?

Answer 15

plays an important role in sequencing of complex movements

Question 16

what does the basal ganglia do in regards to movement?

Answer 16

participates in choice and initiation of voluntary movements

Question 17

what does the motor cortex do?

Answer 17

located in the precentral gyrus, main source of voluntary motor control, initiation and awareness of movement is a result of increased activity in the frontal and parietal lobes

Question 18

what is myasthenia gravis?

Answer 18

when someone’s immune system produces antibodies that bind to nicotinic acetylcholine receptors, causes extreme muscle weakness and fatigue, treated with immunosuppressants or acetylcholine enzyme inhibitors

Question 19

what is muscular dystrophy?

Answer 19

group of inherited diseases characterized by muscle degeneration, caused by abnormalities involving the protein dystrophin, which makes up part of the muscle fiber membrane

Question 20

what is polio?

Answer 20

contagious virus that targets and destroys spinal alpha motor neurons, muscle weakness and paralysis, impaired breathing in more severe cases

Question 21

what is huntington’s disease?

Answer 21

progressive disease caused by abnormal protein accumulation in the brain causing cell death that produces involuntary, jerky movements and cognitive symptoms

Question 22

what is parkinson’s disease?

Answer 22

progressive difficulty in all movements, muscle tremors, frozen facial expression, dopaminergic neurons of the substantia nigra begin to degenerate