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Muscular Tissue Flashcards

(107 cards)

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1
Q

Myofibrils are best described as?

A

Subcellular structures of contractile proteins

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2
Q

Identify a single sarcomere?

A

Distance between two Z lines

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3
Q

Does A band shorten when muscle contracts?

A

No

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4
Q

A muscle biopsy characteristic for Duchene muscular dystrophy would reveal?

A

Marked variation in muscle fibers diameter, with both large and abnormally small fibers

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5
Q

What is the role of protein titin in skeletal muscle?

A

Center the myosin filaments in the middle of the sarcomere, maintain distance between actin and myosin

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6
Q

Which best describes a t tubule?

A

In response to depolorization, activates voltage sensor proteins

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7
Q

Regeneration of skeletal muscle tears happens through which mechanism

A

Satellite cells would differentiate into myoblasts

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8
Q

Which structure transmits impulses for cardiac muscle contraction?

A

Purkinje fibers

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9
Q

Which protein in the troponin complex inhibits the binding of myosin to actin?

A

TnI

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10
Q

What is the connective tissue cover around a SINGLE smooth muscle cell?

A

Endomysium

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11
Q

What is the connective tissue cover around a myofibril?

A

Perimysium

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12
Q

What is the connective tissue cover around a GROUP of muscle myofibrils?

A

Epimysium

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13
Q

Role of TnT?

A

Binds troponin complex to tropomyosin

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14
Q

Role of TnC?

A

Calcium binding receptor, most important for contraction

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15
Q

What does tropomyosin cover on the actin filament?

A

Myosin binding sites

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16
Q

Can smooth muscle cells regenerate and repair?

A

Yes, they respond by undergoing mitosis, regularly replicating in uterus, stomach, blood vessels

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17
Q

What do smooth muscle cells secrete?

A

Connective tissue matrix

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18
Q

What do smooth muscle cells synthesize?

A

Type IV collagen, Type III, Type 1 in some areas like uterus and blood vessels
Elastin, proteoglycans, and glycoproteins

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19
Q

What is the arrangement of Myosin II in smooth muscle cells?

A

Side polar arrangement, maximizes the interaction between myosin and actin filaments

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20
Q

What thin filaments does smooth muscle contain?

A

Actin, tropomyosin, caldesmon, calponin

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21
Q

What does caldesmon and calponin need in order to work properly?

A

Calmodulin

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22
Q

What are caldesmon and calponin?

A

Actin binding proteins that block myosin binding sites

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23
Q

Caveolae can be found where?

A

In smooth muscle cell membrane, usually always with cisterna

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24
Q

What does caveolae invaginations do?

A

Regulate the release of Ca2+ from the SR

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25
Dense bodies in smooth muscle are attached to?
Actin and desmin
26
Desmin attached to the dense bodies and sarcolemma does what to sarcolemma?
Throws sarcolemma in different directions when muscle is contracting
27
Where can mitochondria be found in smooth muscle?
Perinuclear and sub sarcolemma
28
What type of collagen is abundant in smooth muscle?
Type III, reticular fibers
29
Where can the intermediate filament vimentin be found?
Vascular smooth muscle cells
30
Smooth muscle cells often have a ______ appearance when muscle is contracting?
Corkscrew
31
Where can smooth muscle cells be found?
GI tract, blood vessels, uterus, respiratory tract
32
What are GAP junctions in smooth muscle called?
Nexus junction
33
Where can lipofuscin granules be found in an aging adult?
Juxtanuclear area
34
What structural subunit can be found in blood for 2 weeks after suspected myocardial infarction?
TnI
35
What structural subunits get release into blood after MI?
TnT and TnI
36
What marker can we test if we suspect a recent myocardial infarction?
TnI
37
In nonfatal damages to heart, what is the replacement of tissue?
Fibrous connective tissue
38
Why do purkinje cell cytoplasm stain poorly?
Large amounts of glycogen
39
Where can purkinje cells be found?
Endocardium
40
What do purkije fibers do?
Rapidly transmit contractil impulses to various parts of myocardium
41
Cardiac muscle have very large and numberous amounts of?
Mitochondria
42
Explain cardiac DIAD
One SR cisterna and one T tubule
43
T tubules are large and more numerous in?
Cardiac ventricular muscle
44
Where do T tubules run in cardiac muscle compared to skeletal muscle?
T tubules run on Z line in cardiac muscle, and they run at AI junction in skeletal muscle
45
Where can GAP junctions be found in cardiac muscle?
On the lateral component
46
What is the importance of GAP junctions in cardiac muscle?
Provide continuity between adjacent myocytes and allow information to pass cell to cell
47
What provides a cardiac cell to function as a syncytium?
GAP junctions and fascia adherens
48
Where can desmosomes/macula adherens be found in cardiac muscle cells?
Lateral and transverse component
49
What is the function of desmosomes in cardiac muscle?
Prevent cells from pulling apart after repetitive contraction
50
Fascia adherens serves at site where thin filaments of last sarcomere anchor to plasma membrane, therefore coincides with?
Z disc
51
Where can fascia adherens be found in cardiac muscle?
Transverse component, Z disk
52
What is the important protein in cell junctional complexes?
E-cadherins
53
Concentrations of what are present in between myofibrils in cardiac muscle?
Glycogen
54
There a dark atrial granules found in the juxtanuclear region of cardiac muscle, what polypeptide hormones are found in these granules?
ANP and BNP
55
What polypeptide hormone levels increase in congestive heart failure?
BNP
56
Can skeletal muscle be repaired if external lamina is intact?
Yes, satellite cells give rise to myoblasts, which fuse to form myotubules and eventually mature into new muscle fibers
57
Can skeletal muscle be repaired if external lamina is damaged?
No, fibroblasts creates scar tissue
58
What are satellite cells?
Stem cells that can give rise to myoblasts
59
What does the last sarcomere lack in a myotendinous junction?
Z line
60
What are tendons composed of?
Dense regular connective tissue, Type I collagen
61
In myotendinous junction, the actin filaments extend from A band and continue along the length of finger like projections and attach to what?
Sarcolemma
62
In myotendinous junction, finger like projections of ____ penetrate the muscle tissue
Type 1 collagen
63
Where can golgi tendon organ be found?
Tendons
64
What is function of golgi tendon organ?
Respond to increased tension in the muscle, relay information to CNS for coordinating fine muscle contraction
65
Golgi tendon organs only contain what type of nerve?
Sensory/Afferent
66
What is important role of efferent nerve?
To modify information from afferent nerve and send correct information to CNS
67
Are there more chain fibers than there are bag fibers?
Yes
68
Nuceli piled in a central dilation of spindle fibers is called?
Bag fiber
69
Nuclei closely aligned in spindle fibers is called?
Chain fiber
70
What are the two main intrafusal/spindle fibers?
Nuclear chain and bag fibers
71
What is main function of a spindle cell?
Specialized stretch receptors
72
What are the two capsules of spindle cells?
Internal capsule-encloses the spindle fibers External capslue-encloses the entire cell Fluid filled space in between capsules
73
What is role of AChE Acetylcholinesterase?
Breakdown ACh
74
The sarcolemma forms several foldings at neuromuscular junction called?
Synaptic cleft
75
The motor end plate has no?
Myelination
76
Boutons terminal ends are loacted?
In synaptic cleft
77
Schwann cells form a protective cover over?
Dilation of nerve
78
Skeletal muscle fibers are innervated by both?
Motor and sensory innervations
79
What is a TRIAD?
Two terminal cisternae and one T tubule
80
Where are TRIADs located in muscle?
AI junctions
81
Why are TRIADs important?
They couple the extracellular event of nerve coupling with the intracellular responses of calcium ion release
82
What do T tubules contain in skeletal muscle?
Voltage sensor proteins, dihydropiridine receptors
83
Sarcoplasmic reticulum forms a membranoius compartment of flattened?
Terminal cisternae and anastomosing channels
84
Importance of terminal cisternae?
Serve as reservoirs for Ca2+
85
Sarcoplasmic reticulum extends from?
AI junction to adjacent AI junction
86
What protein stores calcium in the SR?
Calsequestrin
87
What does TRIAD provide?
Rapid delivery and removal of Ca2+
88
I and H bands shorten while?
A bands stay the same length
89
Desmin
Attaches Z line to sarcolemma with help of linkage protein ankyrin Crosslinks and stabilizes adjacent myofibrils
90
Dystrophin
Attaches actin to sarcolemma Duchenne muscular dystrophy if gene is disrupted or absent
91
Why do men suffer more from Duchenne Muscular Dystrophy?
It is X linked chromosomal defect, boys only have one X chromosome
92
Myosin Binding Protein C
Helps myomesin protein, provides attachments on either side of M line
93
Myomesin
Myosin binding protein-Holds myosin at M line
94
Nebulin
Aids Alpha Actin in attaching actin to Z disc, maintains length of actin
95
Alpha Actin
Attaches actin to Z line
96
Titin
Maintains precise distance between actin and myosin, also centers mysoin in the middle Molecular springs prevent excessive stretching
97
What does the bare zone in bipolar myosin account for?
H zone
98
Where can bipolar myosin filament be found?
Skeletal muscle
99
Myosin head has two binding sites for what?
ATP and Actin
100
I bands contain only?
Actin
101
H zone contains only?
Myosin
102
A bands contain?
Both myosin and actin
103
M line bisects H band, and Z line bisects?
I band
104
Each thick myosin filament is surrounded by?
6 thin actin filaments
105
Epimysium
CT and Type 1 collagen surrounding a group of muscle fasicles, contains large blood vessels and nerves
106
Perimysium
CT surrounding a group of muscle fibers, contains blood vessels
107
Endomysium
CT and Type 3 collagen surrounding each individual muscle fiber, contains finest vessels and nerve branches

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