Muscle Flashcards
(148 cards)
1
Q
What are the two types of muscle?
A
Striated and smooth
2
Q
A single muscle cell is called what?
A
Muscle fiber
3
Q
Where are the nuclei in skeletal muscle and cardiac muscle?
A
Skeletal: on the edges
Cardiac: in the center
4
Q
Which muscle type has branching?
A
Cardiac
5
Q
Which muscle type has flat nuclei?
A
Smooth
6
Q
Which muscle type has weak, slow contractions?
A
Smooth
7
Q
Which muscle types have involuntary contraction?
A
Cardiac and smooth
8
Q
Endomysium
A
CT that surrounds an individual muscle fiber
9
Q
Perimysium
A
CT that surrounds the fascicles
10
Q
Classification of skeletal muscle fibers is based on:
A
- Contractile speed
- Enzymatic velocity (rate of ATP breakdown by myosin ATPase)
- Metabolic profile (capacity for ATP production)
11
Q
Type I fibers are ___ oxidative.
A
Slow
12
Q
Type IIa fibers are what color?
A
Pink
13
Q
Type IIb fibers are what color?
A
White
14
Q
There are less myoglobin and mitochondria in Type ___ muscle fibers than the others.
A
Type IIb
15
Q
The ___ is made up of the actin and myosin.
A
Myofibril
16
Q
The ___ is made up of the actin and myosin.
A
Myofibril
17
Q
The structural and functional subunit of the myofiber is the ___.
A
Myofibril
18
Q
Z-line to Z-line is one ___.
A
Sarcomere
19
Q
The dark band in the sarcomere is the___.
A
A band
20
Q
The light band in the sarcomere is the ___.
A
I band
21
Q
Is the H band or the A band darker?
A
A band (overlap of myosin and actin)
22
Q
Muscle contraction is ___ dependent.
A
Calcium
23
Q
TnI binds to ___.
A
Actin
24
Q
TnC binds to ___.
A
Calcium
25
TnT binds to ___.
Tropomyosin
26
Where is the actin binding site on the myosin?
On the myosin head
27
The myosin head has ___ activity and the ___ binding site.
ATPase, actin
28
Titin
Large protein that anchors myosin filaments to Z-line
29
The actin is bound to the Z-line by ___ protein.
alpha-actinin
30
Nebulin
Helps stabilize the alpha-actinin + actin interaction at the Z-line
31
Tropomodulin acts as a ___ on the free end of actin.
Cap
32
Myomesin
Hold myosin filaments at the M line in correct orientation
33
C protein
Helps myomesin hold myosin at M line
34
The sliding filament model of muscle contraction
The myosin and actin filaments do not shorten, but increase the degree of overlap
35
Which band does not shorten during contraction? Which do?
A band
| I band, H zone
36
Invaginations in the sarcolemma are called?
T-tubules
37
The modified smooth ER that sequesters calcium is called?
Sarcoplasmic reticulum
38
T-tubules always come in the ___ junction.
A-I
39
T-tubules align at the ___ junction. Why?
A-I
| A-I junction is where the myosin heads and actin interaction occurs
40
Each muscle fiber receives only one innervation from a neuron. T/F
True, alpha motor neurons can innervate multiple muscle fibers, but the fibers are only innervated by that one neuron
41
Muscle and dendrites both have contain junctional folds with the nerve axon. T/F
False, only muscle motor end plates have the junctional folds.
42
Junctional folds on the motor end plate increase the ___ of the presynaptic and postsynaptic membranes of the synapse.
Surface area
43
Golgi tendon organ contain ___ fibers only.
Afferent
44
Stimulation of Golgi tendon organ results in reflex ___ of muscle.
Relaxation
45
The stimulation of muscle spindles due to ___ on muscle causes relfex ___.
Stretch, contraction
46
What is an example of muscle spindle reflex?
Patella / knee jerk reflex
47
Reflex arc loop include the brain. T/F
False
48
Inhibition of ___ causes excess muscle growth.
Myostatin
49
Where are satellite cells located?
Inside the sarcoplasm up against muscle cells, beneath the external lamina of the muscle fiber
50
Satellite cell function
Repair and regeneration of myofibers
| Active, divide and differentiate into myoblasts that fuse with basal lamina to become myotubules
51
Cardiac muscle has regenerative capacity. T/F
False, heart muscle is replaced by CT scar
52
Cardiac muscle is striated. T/F
True
53
Skeletal muscle contains more glycogen, lipids, and mitochondria than cardiac muscle. T/F
False, cardiac muscle requires more energy so it has more glycogen, lipids, and mitochondria
54
Arrangement of cardiac muscle myofibers is in a ___ pattern. Why?
Whorled, allows for wringing out of blood
55
Cardiac muscle also contains CT layers similar to skeletal muscle. T/F
True
56
The ___ portion of cardiac muscle contains fasciae adherens and desomosomes.
Transverse
57
The ___ portion of cardiac muscle contains gap junctions.
Lateral
58
The lateral portion of cardiac muscle contains ___.
Gap junctions
59
Cardiac muscle contains T-tubule system but in a ___ formation.
Dyad
60
The T-tubules are ___ in cardiac muscle than in skeletal muscle. Why?
Larger
| Calcium isn't stored in cardiac muscle because its constantly being used, so its transported via large T-tubules
61
The SR is poorly developed in cardiac muscle and have large T-tubules. Why?
Cardiac muscle doesn't need to store calcium cause they are constantly contracting, so lots of calcium comes in from large T-tubules
62
Atrial (secretory) granules are found in cardiac muscle but not skeletal muscle. T/F
True
63
The heart does not contain motor end plates. T/F
True, SNS and PSNS terminate near muscle cells, not on
64
SNS and PSNS terminate on the muscle cells. T/F
False, they terminate near the muscle cells
65
Purkinje cells are highly enriched with ___.
Glycogen
66
All muscle types contain T-tubules. T/F
False, smooth muscle doesn't contain T-tubules
67
Smooth muscle can contract down to ___% of their length.
25%
68
Smooth muscle can divide. T/F
True
69
In the contracted state, smooth muscle nuclei look like ___.
Spirals
70
Smooth muscle are surrounded by lots of reticular fibers (type III collagen). T/F
True
71
Smooth muscle bring in calcium via ___.
Caveolae
72
Smooth muscle does not have sarcomere arrangement. T/F
True
73
The actin dense bodies are anchored to ___.
Intermediate filaments
74
What are the main intermediate filaments in smooth muscle cells?
Desmin and vimentin
75
In skeletal muscle, tropomyosin is associated with ___?
Thin filament
76
The ends of myofibrils are linked to the cell membrane by ___.
Proteins
77
What are the 2 sensory receptors for muscle?
Muscle spindle and Golgi tendon organ
78
Muscle spindles contain only afferent fibers. T/F
False, they contain both afferent and efferent fibers
79
Muscle makes up ___% of total body weight.
35-45%
80
What are the 3 types of striated muscle?
Skeletal, visceral striated (soft tissue), and cardiac
81
Epimysium
Outermost dense, irregular CT around entire muscle
82
Perimysium
CT that divides the muscle into fascicles
83
What divides the muscle into fascicles?
Perimysium
84
What provides the pathway for capillaries and nerves to supply muscle fibers?
Endomysium
85
Order the skeletal muscle fiber types by smallest to largest
Type I < Type IIa < Type IIb
Small - medium - large
86
Which skeletal muscle fiber types have large myoglobin content?
Type I and Type IIa
87
Which skeletal muscle fiber type has the slowest myosin ATPase?
Type I
88
Type I are ___ twitch while type II are ___.
Slow, fast
89
Which skeletal muscle fiber type is found in hockey players?
Type IIb fast oxidative, glycolytic
90
Which skeletal muscle fiber type is found in weightlifters?
Type IIb fast, glycolytic
91
Which skeletal muscle fiber type has the fastest myosin ATPase?
Type IIb fast, glycolytic
92
Myofibrils are composed of what 2 types of myofilaments?
Actin and myosin myofilaments
93
What is the functional unit of the myofibril?
Sarcomere
94
Even at rest, there is an interaction between actin and myosin. T/F
False
95
___ anchors myosin filaments to the Z lines.
Titin
96
___ anchors actin filaments to the Z-line.
Alpha-actinin
97
___ stabilizes actin / alpha-actinin interaction at Z-line.
Nebulin
98
What 2 proteins function to anchor actin to the Z-disc?
Alpha-actin and nebulin
99
___ acts as a cap on the free end of actin.
Tropomodulin
100
___ holds myosin at the M-line.
Myomesin
101
___ helps the myomesin / myosin interaction at the M-line.
C-protein
102
What 2 proteins function to hold myosin at the M-line?
Myomesin and C-protein
103
Costamere
Connects the Z-disc to the sarcolemma
104
Dystrophin
Links actin to laminin of basal lamina
105
Desmin
Surrounds sarcomere at the Z-line, attaches sarcomere to sarcolemma
106
Titin anchors ___ to ___.
Myosin, Z-disc
107
Alpha-actin anchors ___ to ___.
Actin, Z-disc
108
Myomesin holds ___ at ___.
Myosin, M-line
109
Calsequestrin
Binds calcium in the SR
110
Triad is made up of?
1 T-tubule and 2 terminal cisternae
111
Motor unit recruitment
The force generated by a muscle is dependent on the number of motor units contracting at the same time
112
Muscle spindles
- -Stretch receptors in muscle
- -Made of modified muscle fibers called spindle cells / intrafusal fibers
- -Surrounded by normal muscle fibers (extrafusal)
- -Has both afferent and efferent fibers
- -Leads to stretch reflex
113
Golgi tendon organ (GTO)
- -Monitors tension in muscle
- -Has afferent fibers only
- -Leads to reflex relaxation (inhibition of alpha-motor neurons) to prevent damage during excessive force generation
114
The ___ leads to reflex relaxation while the ___ leads to reflex contraction.
Golgi tendon organ, muscle spindle
115
Intrafusal fibers
The modified muscle fibers of the muscle spindle
| AKA spindle cells
116
Extrafusal fibers
The normal muscle fibers that surround a muscle spindle
117
What are the 2 types of afferent nerves of muscle spindles and what do they respond to?
Annulospiral endings - rate of stretching
Flower spray endings - duration of stretching
118
The reflex loop in the knee jerk reflex is a measure of ___.
CNS function
119
Skeletal muscle develops from the fusion of ___.
Myoblasts
120
___ negatively controls muscle growth and differentiation.
Myostatin
121
Satellite cell location
Beneath the external lamina of the muscle fiber
122
Function of satellite cells
Repair and regeneration of myofibers
| Differentiate into myoblasts, which fuse to external lamina to become myotubes, which mature into myofibers
123
Determine the cellular order of growth and repair of muscle fiber after injury
Satellite cells --> Myoblasts --> Myotubes --> Myofiber
124
If the external lamina is disrupted, ___ repair the injury forming scar tissue.
Fibroblasts
125
Satellite cells form scar tissue. T/F
False
126
Cardiac muscle cells have almost no regenerative capacity. T/F
True
127
Sarcoplasmic cone
Mitochondria and glycogen granules at nucleus
128
Intercalated discs arrange in what fashion?
Step-like, short segments
129
What junctional specializations are present in the transverse portion of the intercalated discs?
Fasciae adherens and maculae adherens
130
What junctional specializations are present in the lateral portion of the intercalated discs?
Gap junctions (desmosomes too)
131
Gap junctions are found on what side of the intercalated discs?
Lateral portion
132
Fasciae adherens are found on what side of the intercalated discs?
Transverse
133
The atrial granules contain?
Atrial natriuretic factor (ANF) and brain natriuretic factor (BNF)
Both diuretics
134
What is the function of the atrial granules?
Release diuretics (ANF and BNF)
135
The stimulus for contraction is delivered to the myocardial cells directly via ___.
Purkinje fibers
136
Purkinje fibers are ___ and have more ___ than cardiac muscle cells.
Larger, gap junctions
137
Purkinje fibers have a lower content of ___ and a higher content of ___.
Myofibrils, glycogen
138
Where is the nucleus located in the muscle cell types?
Skeletal - flat on sides
Cardiac - center
Smooth - center
139
How are the contractile filaments organized in smooth muscle?
Actin filaments linked to plasma membrane and dense bodies in the sarcoplasm
140
Smooth muscle cell nucleus
Central, cork screw shape, deeply indented by contraction
141
Troponin blocks the myosin binding to actin in smooth muscle. T/F
False, the caldesmon and calponin (actin-binding) block myosin binding to actin
142
Dense bodies are functionally comparable to ___.
Z-discs
143
Dense bodies link ___ and ___ to the ___.
Actin, intermediate filaments, sarcolemma
144
Smooth muscle contain T-tubules. T/F
False, they have caveolae
145
Why does the smooth muscle contraction occur more slowly and longer than skeletal muscle?
Slower rate of ATP hydrolysis
146
The myosin II molecules are organized the same as in skeletal muscle. T/F
False, the myosin heads are in opposite directions on each side of the filament
147
Myoepithelial cells
On lumenal side of basal lamina, contract to release products into glands
148
Myofibroblasts
For wound healing, fibroblasts develop contractile ability to close wound
