Muscles and Movement Flashcards

1
Q

What is muscle tissue?

A

long cells called muscle fibers that contract in response to nerve signals
responsible for most forms of movement in complex animals

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2
Q

What are the three types of muscle tissue?

A

skeletal: voluntary movement
smooth: involuntary movement
cardiac: heart contraction

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3
Q

What are the general properties of muscle cells?

A

contractility: interaction of action and myosin to shorten cells
excitability: muscle cells rapidly change ion charge to respond

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4
Q

What is a muscle fiber?

A

a single cell with many nuclei (multinucleate) but with just a single plasma membrane (Sarcolemma)
innervated by a motor neuron to cause contraction

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5
Q

What are myofibrils?

A

bundles of actin and myosin in a muscle fiber

segmented in sarcomeres and highly ordered

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6
Q

Where is actin anchored?

A

the z-line

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7
Q

Where is myosin held?

A

the m-line

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8
Q

How does contraction work?

A

atp driven motors
motors pull actin along myosin
filaments stay the same length, they do not shorten

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9
Q

What is a neuromuscular junction?

A

synapse between neuron and muscle cell

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10
Q

What is acetylcholine?

A

neurotransmitter released by presynaptic neuron

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11
Q

What are t-tubules?

A

extensions of plasma membrane that go deep into the cell

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12
Q

What is the sarcoplasmic reticulum?

A

special ER lining myofibrils; stores Ca2+

releases Ca2+ which inactivates proteins that block myosin-actin binding

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13
Q

What is tropomyosin?

A

a regulatory protein that binds to actin and blocks binding of myosin heads

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14
Q

What determines the precision of movement?

A

the amount of motor units that are recruited

rate at which fibers are stimulated

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15
Q

What is a motor unit?

A

single motor neuron, and all muscle fibers it innervates

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16
Q

What is summation?

A

when multiple signals are received concurrently, it results in more prolonged contraction, allows motions with a gradual increase in tension

17
Q

What is tetanus?

A

individual twitches fuse into sustained contraction

18
Q

What do skeletons provide?

A

support, protection, and scaffolding for motion