Histology: Muscle (Exam 1) Flashcards
1
Q
What produces movement in muscles
A
shortening of muscle fibers
2
Q
What are the contractile proteins found in muscles
A
actin and myosin
3
Q
What are the thin filaments
A
acin
4
Q
What are the thick filaments
A
myosin
5
Q
Why do muscle cells stain eosinophilic
A
due to the proteins
6
Q
What muscles are striated
A
cardiac
skeletal
7
Q
What muscles are voluntary
A
skeletal
8
Q
What muscles are involuntary
A
cardiac and smooth
9
Q
What muscles lack striation
A
smooth
10
Q
Where is smooth muscle found
A
surrounding blood vessels and walls of viscera
11
Q
What is the function of smooth muscle
A
viscera movement
12
Q
How are muscle cells formed
A
aggregation and fusion of myoblasts
13
Q
What is a single cell called in muscle
A
muscle fiber
14
Q
Describe nuclei in skeletal muscle
A
multinucleated
peripherally located under sarcolemma
15
Q
What is muscle strength dependent on
A
the number of fibers
16
Q
What are tendons composed of
A
dense regular connective tissue
17
Q
What do tendons connect
A
muscle to bone or bone to bone
18
Q
What are the three layers of CT around a muscle
A
epimysium
perimysium
endomysium
19
Q
Where is endomysium found
A
surrounding each muscle fiber
20
Q
Where is perimysium found
A
surrounding bundles of muscle fibers
21
Q
Where is epimysium found
A
on the outside of a muscle
22
Q
What type of structure does endomysium have
A
delicate CT
23
Q
What is a myofibril
A
structural and function subunit of a muscle fiber
24
Q
What do collections of muscle fibers form
A
muscle fasicle
25
What do collections of muscle fasicles form
Muscle
26
What is the composition of a myofibril
actin and myosin myofilaments
27
What is a sarcomere
contractile unit of a muscle fiber
28
What are thin filaments in a sarcomere
actin
tropomyosin
troponin
29
What are the thick filaments in a sarcomere
myosin
30
What are the components called in a sarcomere
```
I band
A band
H band
M line
Z line
```
31
What is the I band
range of thin filaments on the end of sarcomeres
32
What is the A band
range of thick filaments from I band to I Band
33
What is the H band
range in the center between thick bands, includes the M line
34
Where is the M line located
middle of the sarcomere
35
Where is the Z line located
in between actin bands, on the edges of a sarcomere
36
What are the parts of the sarcomere that will change with contraction
H and I band get shorter
37
What occurs to the A band during contraction
stays the same length
38
What is the function of dystrophin
anchors z line to cell membrane
39
How is myosin anchored to the m-line
through myomesin
40
What will shorten during skeletal muscle contraction
sarcomere
41
What remains the same length during contraction
myofilaments
42
What structures are found around the sarcoplasmic reticulum in sarcomeres in skeletal muscles
mitochondria and glycogen
43
What regulates contraction of skeletal muscle
calcium
44
What is required for myosin actin to react
calcium
45
What is the function of the sarcoplasmic reticulum in skeletal muscle
reservoir for calcium
46
What does the sarcoplasmic reticulum form to aid in its function
terminal cisternae around myofibrils
47
What are t-tubules
invaginations of plasma membrane into the muscle fiber
48
What is the function of t-tubules
carry the action potential into muscle fiber to allow release of Ca2+ in the cell
49
Do skeletal muscles contain a triad or diad system
triad
50
What is the arrangement of the triad t-tubule system
Triad:
| 2 cisternae and T-tubule
51
What is the reservoir part of the sarcoplasmic reticulum
terminal cisternae
52
Where do terminal cisternae and t tubules form a triad
at the A-I junction
53
How many triads are found per sarcomere
2
54
What leads to excitation of a muscle fiber at the neuromuscular junction
release of acetylcholine from neuron that is taken up by a muscle fiber leading to excitation
55
How does myasthenia gravis affect muscles
NMJ is blocked by antibodies on the muscle end, leading to muscle weakness
the muscles cannot be stimulated
56
What type of disease is myasthenia gravis
auto-immune disease
57
How will botulinum toxin affect muscles
prevent neurotransmitter release
58
What does the presynaptic axon terminal of a NMJ contain
mitochondria and secretory vesicles containing ACh
59
What does the muscle fiber plasma membrane of a NMJ contain
infoldings that contain ACh receptors (Na+ channels)
60
What is a motor unit
motor neuron and all of the muscle fibers it innervates
61
How does innervation determine coordination
smaller ration = the smoother the movement
62
What are proprioceptors
special receptors that sense degree of muscle stretch and tension
63
What do proprioceptors provide info about
feedback about position in space
64
What are the two types of proprioceptors
Golgi tendon organs
| muscle spindles
65
What is the function of extrafusal fibers
contract to generate force
66
What are extrafusal fibers innervated by
alpha motor neurons
67
What is the function of intrafusal fibers
to detect muscle stretch, specialized fibers for proprioception
68
Where are intrafusal fibers found
in muscle spindles
69
What are intrafusal fibers innervated by
motor neurons
70
What is the function of the muscle spindle
responds to changes in muscle length to prevent overstretching
71
What direction do intrafusal fibers run
parallel with the muscle belly
72
How will the muscle spindle respond to overstretching of a muscle
detect stretch and send afferent signal through gamma motor neuron to the CNS
effent signal from CNS will travel through alpha motor neurons to extrafusal fibers causing them to contract and shorten the muscle
73
How many fibers are in a nuclear bag
2-4
74
How many fibers are in a nuclear chain
6-8
75
What is the golgi tendon organ
encapsulated receptor found at junction between muscle and tendon
76
What is the structure of the golgi tendon
afferent nerve endings interwoven between collagen fibrils
77
What is the function of the golgi tendon organ
monitors muscle load for force of contraction
78
What type of cells does cardiac muscle have
```
mononucleated cells
centralized nuclei
striated
intercalated disks
branching
```
79
What are the three components of the intercalated discs in cardiac muscle
Fascia Adherens
Macula adherens
Gap junctions
80
What is the fascia adherens do
anchors thin filaments
81
What component of the intercalated disc does fascia adherens make up
transverse component
82
What are macula adherens
desmosome
83
What does the macula adherens do
hold cells together during repetitive contractions
84
What do gap junctions do
allow cells to communicate
85
What part of the intercalated disc does gap junctions make up
lateral component
86
What does the fascia adherens function as
terminal z line
87
What lines are t-tubules associated with in cardiac muscle
z line
88
What lines are t-tubules associated with in skeletal msucle
A-I junction
89
Describe the sarcoplasmic reticulum in cardiac muscle
only diad
not organized well
terminal cisterne and t-tubule
90
What are purkinje fibers
modified cardiac muscle cells that regulate heartrate
91
Where are purkinje fibers found
in the ventricular walls of the heart
92
WHat is heartrate regulated ultimately by
autonomic nervous system
93
WHere is smooth muscle found
walls of viscera, blood vessels, iris, ciliary body, dartos muscle, erector pili
94
What type of cells does smooth muscle have
fusiform cells with central cork-screw nuclei
95
How do smooth muscle cells communicate
through gap junctions
96
How does smooth muscle contraction differ from other muscle types
prolonged, wave-like contraction
97
Does smooth muscle have a t-tubule system
no
98
How is calcium delivered to the smooth muscle
via caveolae
99
What does calcium do to smooth muscle
cause myosin light chain kinase to phosphorylate myosin
100
What is unique to smooth muscle
myosin light chain kinase phosphorylates myosin
101
What is smooth muscle regulated by
ANS
102
What are dense bodies
proteins located in sarcoplasm of smooth muscle cells
103
What is the function of dense bodies
attach actin filaments so contraction causes a corkscrew twisting that shortens the cell
104
Describe muscle repair and renewal in skeletal muscle
does not renew
| becomes scar tissue
105
What in muscle cells show limited capacity for skeletal muscle fiber differentiation
satellite cells
106
What is necessary for muscle integrity
innervation
107
Describe muscle repair and renewal of cardiac muscle
does not renew in adults
| becomes scar tissue
108
Describe muscle repair and renewal in smooth muscle
have the ability to proliferate
responds to injury via mitosis
