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Whitney - Histology Test 2 > Lecture 17 Skeletal Muscle Tissue > Flashcards

Lecture 17 Skeletal Muscle Tissue Flashcards

1
Q

What are the three muscle types?

A

Skeletal, Smooth, and Cardiac

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2
Q

Skeletal Muscle Characteristics

A 
Multinucleated syncytium 
Peripheral nuclei
Sarcomeric arrangement 
Each fiber innervated via a single motor axon
"all or none" contraction
Troponin C
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3
Q

Formation of skeletal muscle cells (fibers)

A

Formed during embryonic development; hundreds of individual mononucleated myoblasts join end to end to form a myotube
Myotube matures into cylindrical myocyte w/ hundreds of nuclei

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4
Q

Describe Type I Myofibers

A 
Intense staining for oxidative enzymes
Rich in NADH transferase, myoglobin, ATPase
Many Mitochondria
Primarily use Oxidative Phosphorylation 
Slow & continuous contractions
Referred to as dark or red fibers
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5
Q

Describe Type IIA Myofibers

A

Intermediate staining for oxidative enzymes
Aerobic and anaerobic respiration for ATP
Contract more rapidly than Type I
Resistance to fatigue

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6
Q

Describe Type IIB Myofibers

A 
Light staining for oxidative enzymes
Primarily anaerobic respiration for ATP
Contract more rapidly than Type I or Type IIA
Fatigue quickly
Referred to as white or light fibers
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7
Q

Smooth Muscle Characteristics

A 
Single mononucleated cells
No sarcomeric arrangement
Cells innervated via ANS
Do not respond "all or none"
Cell connected via Gap Junctions
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8
Q

Cardiac Muscle Characteristics

A 
Single mononucleated cells
Centrally positioned nuclei
Branching 
Sarcomeric arrangement 
Gap Junctions (intercalated disks)
Not directly innervated
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9
Q

A muscle is composed of many ______

A

fascicles

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10
Q

A fascicle is a bundle of _____

A

myofibers

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11
Q

A myofiber is bundle of ______

A

Myofibrils

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12
Q

A myofibril is a linear array of ______

A

Sarcomeres

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13
Q

A sarcomere is made up of what two types of filaments?

A 
Thin = actin
Thick = myosin
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14
Q

A muscle is covered by a CT tissue sheet called the ______

A

epimysium (abundance of type I collagen)

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15
Q

A fascicle is covered by a CT sheet called the ______

A

Perimysium

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16
Q

What does the perimysium consist of?

A

Fibroblasts and type I collagen

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17
Q

A myofiber is a muscle cell and is surrounded by a cell membrane called the ________

A

Sarcolemma

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18
Q

The ______ covers the muscle fiber, including the sarcolemma

A

Endomysium

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19
Q

The endomysium consists of:

A

A basal lamina and reticular collagen fibers

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20
Q

The basal lamina is secreted by:

A

Muscle cells

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21
Q

What is the function of the basal lamina?

A

Anchors muscle fibers to each other

Helps distribute the force of contraction

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22
Q

Review the structure of a Sarcomere

A

Slide 31

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23
Q

Review Sliding Filament Theory

24
Q

Thick filaments are made up of:

25
Describe Myosin
Dimeric protein with long tails and two head groups
26
Each myosin head group has:
Actin binding region ATP-Binding Region Light-chain binding region (Review slide 38 for more detail)
27
Describe the two pairs of light chains on myosin
Similar to calmodulin, but have lost ability to bind Calcium Essential light chains (stability of heads) Regulatory light chains (stability of myosin II; phosphate binding)
28
Thin filaments are made of:
actin
29
Describe F actin
Polymer of G actin Each actin filament consists of 2 polymers in alpha-helix configuration Plus end inserts on Z-disk
30
Name the two actin-associated molecules
Troponin Tropomyosin (Review slide 41)
31
What are the three troponin molecules?
Troponin I Troponin C Troponin T
32
What is the function of Troponin I?
Inhibits binding between actin and myosin
33
What is the function of Troponin C?
Binds calcium ions
34
What is the function of Troponin T?
Binds to tropomyosin
35
What do we call the enlargements of the sarcoplasmic reticulum?
Cisternae
36
What do cisternae do?
sequester calcium ions
37
What are T-tubules?
Extensions of the sarcolemma that extend down into the sarcoplasm Located at the A-I junction
38
What is the function of T-tubules?
Provide electromechanical coupling for myofiber contraction by transferring the AP of the sarcolemma into calcium release from the cisternae
39
AB-Crystallin
Heat-shock protein that protects desmin from mechanical stress
40
Dystrophin
1 of the proteins that links a-actin/desmin complex to cytoplasmic side of sarcolemma Anchors actin to sarcolemma Reinforces sarcolemma during muscle contraction
41
Dystroglycan complex
Links dystrophin (intracellular) to laminin-2 (extracellular)
42
a-Actinin
Attached thin filaments to the Z line
43
Titin
Large fibrous protein Extends from Z disk to middle of H-band & connects ends of thick filaments to Z-line Provides myosin w/ elasticity Centers thick filaments in the sarcomere
44
Desmin Intermediate Filaments
Framework of desmin filaments which surrounds the Z line & extends into each sarcomere Links myofibrils laterally & to sarcolemma
45
Plectin
Binds desmin filaments
46
Nebulin
Extends from Z disc to end of actin filament | Serves as template to regulate length of actin filaments
47
Muscular Dystrophy
X-linked inherited disease, results in progressive degeneration of skeletal muscle Dystrophin is either absent (Duchenne's) or abnormal (Becker's)
48
Satellite Cell attach to ______ before basal lamina is laid down.
Myotubes
49
Satellite cells function as:
Stem cells
50
Satellite cells can become _____ in times of stress
mitotic | C-Met receptor for HGF
51
Satellite cells give rise to:
Myogenic precursor cells | - Replace damaged muscle by proliferating, fusing, and differentiating into skeletal muscle fibers
52
Neuromuscular Spindle Components
``` Extrafusal Fibers Intrafusal Fibers Alpha Motor Neurons Gamma Motor Fibers/Neurons Primary and Secondary Afferent Fibers ```
53
Intrafusal Fibers
Nuclear bag region = sensory region Nuclear bag fibers Nuclear chain fibers
54
Alpha motor neurons
To extrafusal fibers
55
Gamma motor neurons
To intrafusal fibers

Whitney - Histology Test 2 (11 decks)

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