Chapter 8: Skeletal Muscle Flashcards

1
Q

Functions of skeletal muscle

A
  • force generation for locomotion and breathing
  • force generation for postural support
  • heat production during cold stress
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2
Q

Human body contains over ____ skeletal muscles

A

600

  • 40-50% of total body weight
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3
Q

Fascia

A

Separates individual muscles and holds them in position

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4
Q

Epimysium

A

surrounds entire muscle

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5
Q

Perimysium

A

Surrounds bundles of muscle fibers (fascicles)

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6
Q

Endomysium

A

surrounds individual muscle fibers

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7
Q

External lamina (basement membrane)

A

just below endomysium

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8
Q

sarcolemma

A

muscle cell membrane

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9
Q

Muscle cells (fibers)

A
  • unique shape
  • contain same organelles with other cells (mitochondria)
  • multinucleated
  • striated appearance
    – stripes produced by alternating dark and light bands
  • each muscle fiber extends the entire length of the muscle
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10
Q

Above the sarcolemma and below the external lamina are a group of muscle precursor cells called

A

satellite cells

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11
Q

Satellite cells

A
  • undifferentiated cells involved in muscle growth and repair
  • can be activated to increase number of nuclei which allows for greater protein synthesis
  • important for adaptations to strength training
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12
Q

If muscle cells are destroyed due to injury or disease they _____ be replaced by cell division

A

cannot

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13
Q

Myonuclear domain

A

the volume of cytoplasm surrounding each nucleus

  • each nucleus can support the gene expression (protein synthesis) of a limited myonuclear domain
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14
Q

During growth, to maintain a constant ratio of cell volume per nucleus

A

nuclei from satellite cells are incorporated

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15
Q

hypertrophy

A

increased number of nuclei by activating satellite cells

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16
Q

atrophy

A

decreased number of nuclei

Opposite of muscle growth

17
Q

Myofibrils

A

threadlike structures contain contractile proteins

subdivided into sarcomeres… divided by thin sheet of structural proteins called a Z-line or Z-disk

18
Q

2 major filaments

A

Myosin- thick

Actin- thin

19
Q

A-band

A

myosin filaments in the dark region of the sarcomere

20
Q

I-band

A

actin filaments in the light regions

21
Q

H-zone

A

center of sarcomere with no overlap of actin

22
Q

Structures that play an important role for muscular contractions

A

sarcoplasmic reticulum

transverse tubules

23
Q

Sarcoplasmic reticulum (SR)

A

a network of channels that surrounds each myofibril

  • storage site for calcium
24
Q

Transverse tubules

A

another set of channels extends from sarcolemma into the muscle fiber and passes completely through the fiber

  • transverse tubules pass between two enlarged SR portions called the terminal cisternae
25
Q

Neuromuscular Junction

A

site where motor neuron and muscle fiber meet

26
Q

Motor end plate

A

pocket formed around motor neuron by sarcolemma

27
Q

neuromuscular cleft

A

short gap between neuron and muscle fiber