Exam 3: Skeletal Muscle Tissue Flashcards Preview

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

Flashcards in Exam 3: Skeletal Muscle Tissue Deck (50):
1

List the three types of muscle tissue.

  • Skeletal (voluntary; striated)
  • Smooth (involuntary)
  • Cardiac

2

Skeletal Muscle Characteristics:

 

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

3

Explain an overview of skeletal muscle development.

 

  • 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

4

Identify the tissue sample below

 

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Skeletal Muscle

5

Identify the tissue sample below

 

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Skeletal Muscle

6

Identify the tissue sample below

 

 

 

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Skeltal Muscle

7

Identify the tissue sample below

 

 

 

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Skeletal Muscle

8

What are some characteristics of Smooth Muscle?

 

  • 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

9

Identify the tissue sample below

 

 

 

Q image thumb

Smooth Muscle

10

Identify the tissue sample below

 

 

 

Q image thumb

smooth Muscle

11

Identify the tissue sample below

 

 

 

Q image thumb

smooth muscle, teased

12

Give cardiac cell characteristics

 

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

13

Type I Myofiber:

 

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

14

Type IIA myofiber:

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

15

Type IIB myofiber:

 

  • 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

16

Identify the tissue sample below

 

 

 

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Cardiac Muscle

17

Identify the tissue sample below

 

 

 

Q image thumb

Cardiac Muscle

18

Identify the tissue sample below

 

Q image thumb

Cardiac Muscle, Acute MI

19

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 ________.

 

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

20

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

Epimysium

21

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

 

Perimysium

22

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

 

Myofiber

23

The ___________ covers the muscle fiber, including the sarcolemma

 

Endomysium

24

For reference ONLY

 

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Nothing Back here.

25

Just for reference

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Blank

26

How are the filaments of the sarcomere organized?

 

A repeating banding pattern (viewed microscopically)

27

Sarcomeres are separated from each other by

 

transverse disks called Z-lines/disks

28

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

 

A, i

29

What doe the "A" bands consist of?

 

Thick "myosin" filaments

30

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

 

The length of the bundle of myosin filaments

31

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

 

Z-disks at the opposite ends

32

What forms the "I" bands

 

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

33

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

 

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

34

What are some hallmarks of the sliding filament theory?

 

  • 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

Thick Myofilaments: Myosin

 

  • 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

Thin Myofilaments: Actin

 

  • 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

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

 

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

38

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

 

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

 

39

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

Cisternae

40

What do cisternae in SR do?

 

Sequester calcium Ions

41

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

 

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

42

What is Titin:

 

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

43

What is desmin?

 

  • Extends from one myofibril to another and to sarcolemma

44

What does plectin do?

 

  • Binds desmin filaments

45

What is αß-crystallin?

 

a heat-shock protein that protects desmin from mechanical stress

46

Explain the role of Dystrophin:

 

  • 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

What does the dystroglycan comples do?

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

48

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

 

  • Absent in Duchenne's
  • Abnormal in Becker's

49

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

  • 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

Neuromuscular Spindle

 

TBW