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Cells/Histology, Josh > Exam 3: Skeletal Muscle Tissue > Flashcards

Exam 3: Skeletal Muscle Tissue Flashcards

1
Q

List the three types of muscle tissue.

A
  • Skeletal (voluntary; striated)
  • Smooth (involuntary)
  • Cardiac
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2
Q

Skeletal Muscle Characteristics:

A
  • Multinucleated Syncytium
  • Peripheral Nuclei
  • Sarcomeric Arrangement
  • Each fiber innnervated via a single motor axon
  • Contraction = “all-or-none”
  • Contains Troponin C
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3
Q

Explain an overview of skeletal muscle development.

A
  • Fibers are formed during embryonic development
    • hundreds of ind. mononucleated myoblasts join end-to-end to form a myotube.
  • Myotube matures into the cylindrical myocte with hundreds of nuclei
    • each myocyte is about 50 to 60 micrometers in diameter. compared to 10 micrometers of a typical cell
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4
Q

Identify the tissue sample below

A

Skeletal Muscle

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5
Q

Identify the tissue sample below

A

Skeletal Muscle

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6
Q

Identify the tissue sample below

A

Skeltal Muscle

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7
Q

Identify the tissue sample below

A

Skeletal Muscle

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8
Q

What are some characteristics of Smooth Muscle?

A
  • Single mononucleated cells
  • No sarcomeric Arrangement
  • Cells innervated via ANS
  • Does not respond to “all-or-none”
    • can propagate the impulse themselves
  • Connected via gap junctions
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9
Q

Identify the tissue sample below

A

Smooth Muscle

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10
Q

Identify the tissue sample below

A

smooth Muscle

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11
Q

Identify the tissue sample below

A

smooth muscle, teased

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12
Q

Give cardiac cell characteristics

A
  • Single mononucleated cells
  • centrally positioned nuclei
  • Sarcomeric arrangement
  • Communicate via gap junctions
    • inercalated discs
  • cells not directly innervated
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13
Q

Type I Myofiber:

A
  • Referred to as dark or red fibers
    • slow sustained activity
  • Utilize oxidative phosphorylation
  • many mitochondria
  • rich in NADH transferase, myoglobin, ATPase
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14
Q

Type IIA myofiber:

A
  • Intermediate staining for oxidative enzymes
  • both aerobic and anaerobic respiration for ATP production
  • contract more rapidly than type I fibers
  • RESISTANCE TO FATIGUE
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15
Q

Type IIB myofiber:

A
  • Light Staining for oxidative enzymes
  • Primarily anaerobic respiration for ATP production
  • Contract more rapidly than type I or IIA fibers
  • Fatigue Quickly
  • White or light fibers
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16
Q

Identify the tissue sample below

A

Cardiac Muscle

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17
Q

Identify the tissue sample below

A

Cardiac Muscle

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18
Q

Identify the tissue sample below

A

Cardiac Muscle, Acute MI

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19
Q

A muscle is composed of many ________, which is a bundle of __________, which is a bundle of ________. A ________ is a linear array of __________, which is made up of filaments. The thin filaments are ______, while the thick filaments are ________.

A

fascicles, myofibers, myofibrils, Myofibril, sarcomers, actin, myosin

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20
Q

A muscle is covered by a connective tissue sheet called the __________.

A

Epimysium

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21
Q

A fascicle is surround by a connective tissue sheet called the ___________, which consist of fibroblast and type I collagen fibers.

A

Perimysium

22
Q

A ________ is a muscle cell and is surrounded by a cell membrane call the sarcolemma.

A

Myofiber

23
Q

The ___________ covers the muscle fiber, including the sarcolemma

A

Endomysium

24
Q

For reference ONLY

A

Nothing Back here.

25
Q

Just for reference

A

Blank

26
Q

How are the filaments of the sarcomere organized?

A

A repeating banding pattern (viewed microscopically)

27
Q

Sarcomeres are separated from each other by

A

transverse disks called Z-lines/disks

28
Q

Each sarcomere consists of a Middle “__” band Flanked By two “__” bands

A

A, i

29
Q

What doe the “A” bands consist of?

A

Thick “myosin” filaments

30
Q

What is the width/length of the A band equal to?

A

The length of the bundle of myosin filaments

31
Q

In the sarcomere actin filaments interdigitate into each end of the myosin filament bundle and are attached to the _______

A

Z-disks at the opposite ends

32
Q

What forms the “I” bands

A

the portion of the actin filament not within the myosin bundle.

33
Q

What does the H band consist of and where is it found?

A

Thick (myosin) filaments and is located in the middle of the A band

34
Q

What are some hallmarks of the sliding filament theory?

A
  • Width of the A band does not change during a contraction
  • Width of the I bands become shorter during a contraction
  • Width of the H Band decreases during a contraction and the H band my disappear
  • Distance between the 2 successive z-disk becomes shorter
    • sarcomere shortens
  • Shortening of all sarcomeres within muscle fiber results in the shortening of the muscle fiber during contraction
35
Q

Thick Myofilaments: Myosin

A
  • Two identical heavy chains
    • head @ each end of chain
    • actin binding region
    • ATP binding region
    • light chain binding region
  • Two pairs of light chains
    • essential light chains
    • Regulatory Light Chains
36
Q

Thin Myofilaments: Actin

A
  • F-actin
    • polymer of G actin
    • actin filament consist of 2 polymers in alpha helix
      • end inserts on Z-disk
  • Actin-associated molecules
    • Troponin
    • Tropomyosin
37
Q

Troponin is a complex of three molecules what are they and what do they do?

A
  • Troponin I:
    • inhibits binding btwn actin/myosin
  • Troponin C:
    • binds calcium ions
  • Troponin T:
    • Bind to tropomyosin
38
Q

Where does tropomyosin sit, and how many actin monomers does it span?

A

sits in the groove between two f-actin strands of an actin filament, spans 7 actin monomers

39
Q

Enlargements of the SR are located next to T-tubules and are referred to as

A

Cisternae

40
Q

What do cisternae in SR do?

A

Sequester calcium Ions

41
Q

T-tubules are ext of the Sarcolemma that extend down into the sarcoplasm, located at the A-I junctions. What is their function?

A

Provide electomechanical coupling for myfiber contractions by transferring the action potential of the sarcolemma into calcium release from the cisternae

42
Q

What is Titin:

A
  • A very large protein
  • extends from Z-disk to middle of H-band
  • Provides myosin with elasticity
43
Q

What is desmin?

A
  • Extends from one myofibril to another and to sarcolemma
44
Q

What does plectin do?

A
  • Binds desmin filaments
45
Q

What is αß-crystallin?

A

a heat-shock protein that protects desmin from mechanical stress

46
Q

Explain the role of Dystrophin:

A
  • a calponin, links actin filaments to transmembrane proteins of muscle cell plasma membranes
  • links to the extracellular matrix, which helps maintain cell stability during muscle contraction
47
Q

What does the dystroglycan comples do?

A

links dystrophin (intracellular) to laminin-2 (extracellular)

48
Q

How does dystrophin affect pts with Duchenne’s or Becker’s musclar dystrophy respectively?

A
  • Absent in Duchenne’s
  • Abnormal in Becker’s
49
Q

Describe the role of satellite cells in repair, maintenace, and regeneration of skeletal muscle tissue.

A
  • attach to myotubes before basal lamina is laid down
  • generally quiescent
  • Can become mitotic in times of stress
    • C-Met receptor
    • HGF
  • Give rise to myogenic precursor cells
    • Undergo several cycles of mitosis before fusing with myofibers
50
Q

Neuromuscular Spindle

A

TBW

Cells/Histology, Josh (15 decks)

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