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IMSK Exam 1 > Skeletal Muscle Structure and Function > Flashcards

Skeletal Muscle Structure and Function Flashcards

1
Q

What are qualities of muscles with parallel arrangement?

A

Rapid shortening but with less tension

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2
Q

What are the qualities of muscles with fivers at an angle to the axis of shortening?

A

Slow shortening but with greater tension

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3
Q

What is the order of muscle arrangement from macro to micro?

A

Muscle-> Fascicle-> Muscle Fiber-> Myofibril-> Sarcomere-> Thick/Thin filaments

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4
Q

What does the epimyisium cover?

A

The whole muscle

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5
Q

What does perimysium cover?

A

The fascicle

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6
Q

What does the endomysium cover?

A

The muscle fiber

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7
Q

Where do all three muscle covering connect?

A

To the tendon

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8
Q

What occurs with a single motor unit?

A

One motor unit innervates all the muscle fibers

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9
Q

What occurs with two motor units?

A

Some of the muscle fibers are innervated by one motor unit and the rest are innervated by the other motor unit; motor units are all the same they can just affect different muscle fibers

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10
Q

For fine movements what is true of the motor units?

A

There are few motor units per muscle fibers

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11
Q

What are satellite cells?

A

Muscle stem cells found between the basement membrane and sarcolemma

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12
Q

When are satellite cells activated?

A

When a muscle is damaged (can be by multiple means)

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13
Q

The application of what stains myocyte nuclei blue?

A

Hemalum

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14
Q

What are the three biochemical systems that are the basis of muscle function?

A

Metabolic system
Calcium regulation
Contractile

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15
Q

Where is ATP expended when a myocyte is active?

A

1/3 to calcium regulation and 2/3 to cross-bridge cycling

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16
Q

Where is ATP expended when a myocyte is inactive?

A

Ion transport and protein synthesis

17
Q

What is titin?

A

A protein that allows for passive tension (springy); needed for the left ventricle to fill with blood in between contractions

18
Q

What is a main determinant of muscle function?

A

Myosin isoforms

19
Q

What are Type I fibers?

A

Slow-oxidative fibers (slow twitch)

20
Q

What are Type II A fibers?

A

Fast-oxidative fibers (intermediate)

21
Q

What are Type II X fibers?

A

Fast-glycolytic fibers (fast twitch)

22
Q

The recruitment of muscle motor units occurs in what predetermined sequence?

A

Type I-> Type IIA-> Type IIX

23
Q

What are the three systems needed for a myocyte to function?

A

Metabolic
Calcium recycling
Cross-bridge cycling

24
Q

What is the H band?

A

Zone across the center of the sarcomeres of skeletal muscle; contains only myosin filaments

25
Q

What is the I band?

A

Light band on each side of Z line; contains only thin (actin) filaments

26
Q

What is the M band?

A

Runs directly through the center of the A band

27
Q

What is the A band?

A

Spans the myosin filaments; overlaps with some of the actin filaments

28
Q

What defines one sarcomere?

A

The segment between two neighboring Z-lines

29
Q

What is the ratio of actin to myosin filaments?

A

2:1

30
Q

What happens to the bands when a muscle contracts?

A

H-band shortens
I-band is shortened
A-band is unchanged

31
Q

What is titin?

A

A protein needed for passive tension giving muscles a spring-like property; it is important in the filling of blood into the left ventricle

32
Q

What is the clinical association of titin mutations?

A

Associated with hereditary myopathy with early respiratory failure

33
Q

What is a biomarker for acute MI?

A

Troponin: TnI and TnC

34
Q

How are different muscle types differentiated in a muscle biopsies?

A

Myosin heavy chain isoforms

35
Q

What MyHC isoform is found in Type-1 fibers?

A

MyHC I

36
Q

What MyHC isoforms are found in IIX and IIA muscle forms?

A

MyHC IIx and MyHC IIa and MyHC IIb (have genes but not expressed in humans)

37
Q

What is the main determinant of muscle function?

A

Myosin isoforms

38
Q

Which muscle type has the highest and lowest amount of mitochondria respectively?

A

Type I

Type IIX

39
Q

What implications does the order of motor unit recruitment have?

A

Rehabilitation

IMSK Exam 1 (15 decks)

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