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EPCC Anatomy and Physiology 1 > Chapter 10 Highlights > Flashcards

Chapter 10 Highlights Flashcards

1
Q

Myocyte

A

Muscle cell

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2
Q

Sarcoplasm

A

Myocyte cytoplasm

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3
Q

Sarcolemma

A

Myocyte plasma membrane

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4
Q

Sarcoplasmic Reticulum (SR)

A
  • Modified endoplasmic reticulum
  • Forms web-like network surrounding myofibrils
  • Varies in structure in three types of muscle tissue
  • Stores and released calcium ions
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5
Q

Myofibrils

A
  • Bundles of specialized proteins

- Allow for contraction

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6
Q

Composition of skeletal muscle tissue

A

Fibers and endomysium

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7
Q

Skeletal muscle (organization)

A
  • Surrounded by epimysium

- Contains muscle fascicles

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8
Q

Muscle fascicles (organization)

A
  • Surrounded by perimysium

- Contains muscle fibers

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9
Q

Muscle fibers (organization)

A
  • Surrounded by endomysium

- Contains myofibrils

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10
Q

Myofibrils (organization)

A
  • Surrounded by sarcoplasmic reticulum

- Contains sarcomeres (Z line to Z line)

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11
Q

Sarcomere

A
  • Contains thick and thin filaments
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12
Q

Transverse tubules

A
  • Deep inward extensions of sarcolemma
  • Surrounds each myofibril
  • Continuous with exterior of cell
  • Filled with extracellular fluid
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13
Q

Terminal cisternae

A
  • Enlarged sections of SR

- Flank each t-tubule

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14
Q

Triad

A

Two terminal cisternae plus corresponding t-tubule

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15
Q

Thick filaments

A
  • Myosin

- Binds to actin

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16
Q

Thin filaments

A

Actin, tropomyosin, and troponin

17
Q

Elastic filaments

A
  • Single massive, spring-like structural protein (titin)
  • Stabilizes myofibril structure
  • Resists excessive stretching
18
Q

Tropomyosin

A
  • Long, rope-like regulatory protein

- Twists around actin, covering up active sites

19
Q

Troponin

A
  • Small globular regulatory protein
  • Holds tropomyosin in place
  • Assists with turning contractions on and off
20
Q

I band

A

Only thin filaments

21
Q

Z disc

A
  • In middle of I band

- Structural proteins that anchor thin filaments in place and to one another

22
Q

A band

A
  • Zone of overlap
  • Both thick and thin filaments
  • Generate tension during contraction
23
Q

H zone

A

Middle of A band where only thick filaments exist

24
Q

M line

A
  • Dark line in the middle of A band
  • Structural proteins hold thick filaments in place
  • Serve as anchoring point for elastic filaments
25
Q

Steps of sliding filament cycle

A
  • Action potential reaches the SR and calcium is released
  • Calcium binds to troponin
  • Troponin moves, moving tropomyosin and exposing actin active site
  • Myosin hinges, myosin head forms cross bridge with actin and moves actin towards the M line, eliminating H zone and I band
  • ATP allows release of cross bridge and leaves myosin reenergized
  • Calcium (80%) is pumped back to the SR
26
Q

What happens to I band during contraction?

A

Narrows

27
Q

What happens to H zone during contraction?

A

Narrows

28
Q

What happens to A band during contraction?

A

Unchanged

29
Q

What does myosin attach to?

A

Actin

30
Q

What does myosin do to the myofilaments?

A

Myosin pulls thin filaments toward M line

31
Q

What is rigor mortis?

A

Progressive stiffening of skeletal muscles

32
Q

When does rigor mortis occur?

A

3-4 hours after death

33
Q

Why does rigor mortis occur?

A
  • Pumps that drive Ca back into SR have no more ATP to fuel activity
  • Ca remains in cytosol, binds to troponin and initiates contraction
34
Q

Why does the stiffness of rigor mortis remain?

A

Muscles cannot relax without ATP, so myosin heads cannot detach from actin

35
Q

How long does rigor mortis last?

A
  • Contraction remains until myofilament proteins degenerate

- About 48-72 hours after death

EPCC Anatomy and Physiology 1 (24 decks)

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