Muscle Contraction

Question 1

sarcomeres change ______ during muscle depolarization

Answer 1

length

Question 2

The _____ segment of myosin has ATP and actin binding sites

Answer 2

S-1

Question 3

the heavy myosin chains form the ____ region and the light myosin chains form the ______ region of the molecule

Answer 3

• tail

- globular head

Question 4

myosin filaments form structures with 2 polypeptides in a ______ arrangement

Answer 4

alpha-helix (the tail region)

Question 5

myosin heads project off of the thick filament every ____ degrees

Answer 5

60

Question 6

_______: a 40 nm long fibrous protein that spans 7 G-actin myosin binding sites (inhibitory protein)

Answer 6

tropomyosin

Question 7

during muscle relaxation, ______ is elevated out of the actin helical groove

Answer 7

tropomyosin

Question 8

Ca++ binds to ______, which regulates the movement of tropomyosin

Answer 8

troponin

Question 9

The Length-Tension Relationship states that force is proportional to __________

Answer 9

crossbridge overlap

Question 10

___________: a single motor neuron and all of the muscle fibers it innervates

Answer 10

motor unit

Question 11

a single motoneuron will innervate _________ to __________ muscle fibers

Answer 11

hundreds to thousands

Question 12

the fibers of a single motor neuron are all __________ similar

Answer 12

biochemically

Question 13

the ___________ describes the relationship between the number of muscle fibers innervated by a motoneuron and the degree of control exerted

Answer 13

innervation ratio

Question 14

fine motor control occurs with a ____ fiber:neuron ratio and coarse motor control occurs with a _____ fiber:neuron ratio

Answer 14

• low

- high

Question 15

skeletal muscle has a ________ type acetylcholine receptor

Answer 15

nicotinic

Question 16

___________ or __________ can also activate muscle, but are inactivated more slowly than acetylcholine

Answer 16

• nicotine

- carbamylcholine

Question 17

Muscle Action Potential (MAP) triggers conformational changes in the ______________ proteins

Answer 17

DHP/Ryanodine receptor-like proteins

Question 18

normal muscle at rest should have ________ EMG activity

Answer 18

little/no

Question 19

_________ is associated with the slowing of nerve conduction velocity

Answer 19

demyelination

Question 20

__________ are disease states of the following cell types:

• cell bodies
• axons
• Schwann cells
• mixed

Answer 20

neuropathies

Question 21

________ are disease states associated with the following structures:

• presynaptic - axon terminals
• synaptic cleft
• postsynaptic - sarcolemma

Answer 21

junctionopathies

Question 22

_________ are disease states associated with the myofibers

Answer 22

myopathies

Question 23

3 presynaptic muscle disorders

Answer 23

• hypocalcemia
• hypercalcemia
• botulinum toxin

Question 24

______ is a presynaptic disorder marked by weakness, tetany, spontaneous EMG activity, and reduced acetylcholine release

Answer 24

hypocalcemia

Question 25

________ is a presynaptic disorder marked by weakness due to continuous depolarization and spontaneous EMG activity (increased synaptic vesicle release)

Answer 25

hypercalcemia

Question 26

______ causes a presynaptic disorder described as ‘functional denervation’. Presynaptic binding inhibits acetylcholine release.

Answer 26

botulinum toxin

Question 27

3 post-synaptic neuromuscular disorders

Answer 27

• muscular dystrophy
• myasthenia gravis
• Conotoxin

Question 28

_________: post-synaptic disorder caused by the lack of the structural protein dystrophin

Answer 28

muscular dystrophy

Question 29

What condition is described by the following symptoms?

• leaky muscle cells, high creatine kinase levels
• progressive weakness
• EMG shows repetitive high frequency discharges

Answer 29

muscular dystrophy

Question 30

_________: post-synaptic disorder in which acetylcholine receptors are destroyed (or genetically reduced in numbers)

Answer 30

Myasthenia gravis

Question 31

What is the treatment for Myasthenia Gravis?

Answer 31

acetylcholinesterase inhibitors

Question 32

In which condition is acetylcholine destroyed before it can become receptor bound?

Answer 32

Myasthenia Gravis