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Physiology > Skeletal muscle > Flashcards

Skeletal muscle Flashcards

1
Q

Name at least 2 functions of skeletal muscle.

A

body movement, body posture, respiration, body heat and largest metabolic organ

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2
Q

sarcoplasm

A

cytoplasm

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3
Q

Sarcolemma

A

cell membrane

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4
Q

Where is calcium stored in the muscle fiber?

A

sarcoplasmic reticulum

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5
Q

What are thick and thin filaments?

A

Actin in thin and Myosin is thick

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6
Q

What are the two regulatory proteins bound to actin? What are their functions?

A

Troponin and tropomyosin. Troponin binds to actin and tropomyosin and has a calcium-binding site.

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7
Q

What two binding sites are located on the myosin head?

A

Actin and ATP binding site

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8
Q

Do actin and myosin filaments change length during muscle contraction?

A

no, they merely slide past one another

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9
Q

what is a motor unit?

A

a group of muscle fibers innervated by one axon. A single motor unit innervates one muscle fiber

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10
Q

what is the neurotransmitter used at the neuromuscular junction?

A

Acetylcholine

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11
Q

What opens sodium channels on the sarcolemma?

A

Acetylcholine diffuses across the cleft to bind with ligand-gated Na+ channels

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12
Q

What does depolarization of the sarcolemma do to the SR?

A

Opens Ca channels causing a rapid diffusion of calcium into the cell from the SR

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13
Q

Where does calcium bind to in the sarcoplasm?

A

binds to troponin

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14
Q

What does troponin move? How does this initiate contraction?

A

troponin pulls tropomyosin off the myosin binding site of actin to allow the binding of myosin.

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15
Q

What opens calcium channels in the SR?

A

neurotransmitters binding to their receptors

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16
Q

what is a charged myosin head?

A

when ATP is broken down the energy from ATP is transferred to the myosin head

17
Q

What is required for a charged myosin head to bind to actin?

A

ATP

18
Q

What is a power stroke? Is ATP hydrolyzed during the power stroke?

A

when the binding of actin causes myosin head to tilt. Yes it is hydrolyzed to ADP and phosphate

19
Q

How does the myosin head release from the actin filament?

A

ATP binding to the myosin head

20
Q

What would happen to someone’s muscles who took a drug that prevented calcium from re-entering the SR?

A

muscles would not be able to contract

21
Q

How is calcium removed from the sarcoplasm?

A

through the ATPase pump

22
Q

Describe the events leading to muscle relaxation.

A

nerve impulse ends and calcium is no longer released from the SR. Ca is pumped back into SR by another ATPase pump. CA concentration decreases in the sarcoplasm and there is none left to bind to troponin and tropomyosin returns to its position covering the binding sites on actin.

23
Q

eccentric contraction

A

increase in muscle length

24
Q

concentric

A

decrease of muscle length

25
Q

isotonic

A

muscle contraction at different lengths but same tension

26
Q

isometric

A

muscle contraction without change in length (posture)

27
Q

what is summation

A

When multiple electrical stimuli are applied to a muscle at a sufficiently high frequency, twitches merge into higher force contractions

28
Q

Increasing the rate of firing of a single motor unit would be an example of what kind of summation?

A

frequency summation and tetanus

29
Q

Multiple motor units contracting simultaneously results in what kind of summation?

A

spatial summation

30
Q

What determines the amount of force that is produced from a motor unit?

A

recruitment of slow and fast twitch muscle fibers

31
Q

Where is the muscle spindle located? What does it sense?

A

located within the muscles (intramural fibers) and sense changes in muscle length and how quickly a muscle changes in length

32
Q

What is the GTO? Where is it located?

A

Golgi tendon organs and are located within the tendon near its junction ith a muscle and sense changes in muscle tension

33
Q

Can you increase the activation of the GTO without changing the stimulation of the muscle spindle?

A

Yes

Physiology (10 decks)

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