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BIOL 223 > Structure of Skeletal Muscle Cells > Flashcards

Structure of Skeletal Muscle Cells Flashcards

1
Q

What are the three types of muscle tissue?

A

Skeletal
Cardiac
Smooth

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2
Q

Skeletal muscle is

A

attached to bone
striated
voluntary

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3
Q

Cardiac muscle is

A

found in the heart
striated
involuntary

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4
Q

Smooth muscle

A

lines hollow organs
non-striated
involuntary

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5
Q

What are the functions of skeletal muscle?

A 
Skeletal movement
Maintain posture
Support soft tissues
Guard entrances/exits
Maintain body temp
Nutrient Reserves
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6
Q

Define origin

A

attached to bone, remains relatively stationary during movement

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7
Q

Define insertion:

A

attached to bone, moves during contraction

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8
Q

Tendons

A

attach muscle to bone

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9
Q

Define synergistic muscles

A

muscles work together during a contraction

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10
Q

Define antagonistic muscles

A

Muscles that oppose each other during a contraction (ex. flexors and extensors)

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11
Q

What is the endomysium

A

covers individual muscle cells

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12
Q

What is the perimysium

A

Sheathes bundles of muscle fibers (fascicles)

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13
Q

What is the epimysium

A

Membrane surrounding a muscle

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14
Q

What is deep fascia

A

Wrap groups of cooperating muscles together

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15
Q

What connective tissues in skeletal muscles contain blood vessels and nerves?

A

Endomysium and Perimysium

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16
Q

Describe skeletal muscle cells/fibers

A 
Multinucleate
Very long
Formed during embryogenesis 
Adult muscle repair is limited
Contains myofilaments
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17
Q

Satellite cells

A

create new skeletal muscle cells

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18
Q

Actin

A

thin myofilaments

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19
Q

Myosin

A

Thick myofilaments

20
Q

What is the Sarcolemma?

A

Skeletal cell membrane

21
Q

____ conduct ation potentials deep into skeletal muscle cells and are close to sarcoplasmic reticulum

A

Transverse (T) tubules

22
Q

In skeletal muscle cells action potentials are propogated

A

perpendicular to surface via t tubules

23
Q

Sarcoplasmic reticulum stores a high concentration of _____ ions needed for muscle contraction

A

Ca2+

24
Q

What excites the SR and tells it to release calcium?

A

T-tubules

25
Q

Describe myofibrils

A

Bundles of myofilaments
Can actively shorten
Anchored to inner surface of sarcolemma at each end of the cell

26
Q

What is a sarcomere

A

repeating units of myofilaments in myofibril

27
Q

Sarcomeres are where we actually have contraction where

A

thick and thin myofilaments are overlapping

28
Q

_____ gives banded appearance

A

differences in distribution of thick and thin myofilaments

29
Q

I bands

A

Light band

Contains only thin filaments

30
Q

A bands

A

Dark band

contains thick filaments and some overlap with thin filaments

31
Q

____ band contains only thick filaments

A

H bands

32
Q

What is the Z disk?

A

Border between sarcomeres

33
Q

Muscles shorten during contraction because

A

The myosin and actin filaments slide between each other to shorten each sarcomere

34
Q

As thin filaments move toward center of sarcomere

A

Thin filaments slide over thick
Z lines pull close together
I bands and H band narrow
A band stays same width

35
Q

When is a sarcomere at maximum shortening?

A

When its the width of the A band, no I band or H band are visible

36
Q

Where do cross bridges form?

A

Myosin filaments have short projections that bind to sites on actin filaments

37
Q

_____ use ATP to change shape and pull the actin and convert chemical energy to mechanical energy

A

Cross bridges

38
Q

What part of myofilaments form cross bridges during contraction?

A

Globular heads

39
Q

Interactions between myosin head and actin prevented by ____ during rest

A

tropomyosin

40
Q

Which type of myofilament has an actin active site that are covered by tropomyosin during rest?

A

Thin myofilaments

41
Q

What is the sliding filament theory?

A
  1. Calcium released from SR
  2. Calcium binds to troponin
  3. Troponin moves
  4. tropomyosin moves
  5. Actin Active sites exposed
  6. Cross bridge forms
  7. ATP allows release of cross bridge.
42
Q

What is the role of ATP in the molecular mechanism of contraction?

A
  • Supplies energy to move the myosin head

- Binds to un-energized myosin head

43
Q

______ re energizes myosin head

A

hydrolysis of ADP to ATP

44
Q

_____ causes crossbridge release

A

Binding ATP to myosin head

45
Q

What ion concentration around the sarcomere controls sarcomere contraction?

A

Ca2+

46
Q

When calcium ion levels fall

A

tropomyosin covers actin active sites and ends contraction

BIOL 223 (9 decks)

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