Exam 3: Skeletal Muscle Tissue

Question 1

List the three types of muscle tissue.

Answer 1

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

Question 2

Skeletal Muscle Characteristics:

Answer 2

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

Question 3

Explain an overview of skeletal muscle development.

Answer 3

• 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

Question 4

Identify the tissue sample below

Answer 4

Skeletal Muscle

Question 5

Identify the tissue sample below

Answer 5

Skeletal Muscle

Question 6

Identify the tissue sample below

Answer 6

Skeltal Muscle

Question 7

Identify the tissue sample below

Answer 7

Skeletal Muscle

Question 8

What are some characteristics of Smooth Muscle?

Answer 8

• 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

Question 9

Identify the tissue sample below

Answer 9

Smooth Muscle

Question 10

Identify the tissue sample below

Answer 10

smooth Muscle

Question 11

Identify the tissue sample below

Answer 11

smooth muscle, teased

Question 12

Give cardiac cell characteristics

Answer 12

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

Question 13

Type I Myofiber:

Answer 13

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

Question 14

Type IIA myofiber:

Answer 14

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

Question 15

Type IIB myofiber:

Answer 15

• 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

Question 16

Identify the tissue sample below

Answer 16

Cardiac Muscle

Question 17

Identify the tissue sample below

Answer 17

Cardiac Muscle

Question 18

Identify the tissue sample below

Answer 18

Cardiac Muscle, Acute MI

Question 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 ________.

Answer 19

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

Question 20

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

Answer 20

Epimysium

Question 21

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

Answer 21

Perimysium

Question 22

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

Answer 22

Myofiber

Question 23

The ___________ covers the muscle fiber, including the sarcolemma

Answer 23

Endomysium

Question 24

For reference ONLY

Answer 24

Nothing Back here.

Question 25

Just for reference

Answer 25

Blank

Question 26

How are the filaments of the sarcomere organized?

Answer 26

A repeating banding pattern (viewed microscopically)

Question 27

Sarcomeres are separated from each other by

Answer 27

transverse disks called Z-lines/disks

Question 28

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

Answer 28

A, i

Question 29

What doe the "A" bands consist of?

Answer 29

Thick "myosin" filaments

Question 30

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

Answer 30

The length of the bundle of myosin filaments

Question 31

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

Answer 31

Z-disks at the opposite ends

Question 32

What forms the "I" bands

Answer 32

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

Question 33

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

Answer 33

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

Question 34

What are some hallmarks of the sliding filament theory?

Answer 34

* 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

Question 35

Thick Myofilaments: Myosin

Answer 35

* 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

Question 36

Thin Myofilaments: Actin

Answer 36

* 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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

Cisternae

Question 40

What do cisternae in SR do?

Answer 40

Sequester calcium Ions

Question 41

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

Answer 41

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

Question 42

What is Titin:

Answer 42

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

Question 43

What is desmin?

Answer 43

* Extends from one myofibril to another and to sarcolemma

Question 44

What does plectin do?

Answer 44

* Binds desmin filaments

Question 45

What is αß-crystallin?

Answer 45

a heat-shock protein that protects desmin from mechanical stress

Question 46

Explain the role of Dystrophin:

Answer 46

* 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

Question 47

What does the dystroglycan comples do?

Answer 47

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

Question 48

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

Answer 48

* Absent in Duchenne's * Abnormal in Becker's

Question 49

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

Answer 49

* 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

Question 50

Neuromuscular Spindle

Answer 50

TBW