6.1 lect - types of muscle Flashcards
1
Q
2 types of muscle cells can exist outside of “muscle tissue,” what are they, what germ layers are they derived from, and where are they found?
A
- myofibroblasts, from mesenchyme, ct
- myoepithelial cells, from ectoderm, epithelia
2
Q
which free muscle cells come from the mesoderm and which come from the ectoderm?
A
mesoderm - myofribroblasts
ectoderm - myoepithelial cells
3
Q
RBCs dispersed in connective tissue probably indicates…
A
a wound
4
Q
myosin expressed in connective tissue =
A
a myofibroblast
5
Q
myosin expressed in epithelial tissue =
A
a myoepithelial cell
6
Q
myofibroblast
A
myosin expressed in connective tissue
7
Q
myosin expressed in epithelial tissue
A
myoepithelial cell
8
Q
where might you expect to find myoepithelial cells?
A
basally in glandular epithelium to help squeeze out secretions
9
Q
myofibroblasts are derived from __
A
mesenchyme
10
Q
myoepithelial cells are derived from __
A
ectoderm
11
Q
visceral smooth muscle =
A
smooth muscle surrounding visceral organs
12
Q
appearance of a myofibroblast LM
A
fusiform, basophilic cytoplasm
13
Q
this cell has ~shape of a fibroblast when relaxed but contracts into a corkscrew shape
A
smooth muscle cell
14
Q
actin, dense bodies, and intermediate filaments are components of what cell type?
A
smooth muscle cell
15
Q
what are the intermediate filaments in smooth muscle?
A
arteries / veins - vimentin
most other places - desmin
16
Q
how are dense bodies attached to one another
A
intermediate filaments (to transmit force)
arteries / veins - vimentin
most other places - desmin
17
Q
greek root for muscle
latin root for muscle
A
sarco
myo
18
Q
sarcolemma
A
muscle plasma membrane
19
Q
muscle plasma membrane
A
sarcolemma
20
Q
pinocytotic vesicles in smooth muscle plasma membrane
A
caveoli
- regulate intracellular Ca++ concentrations
- slow regulation but ok because smooth muscle acts slowly / gradually
21
Q
T/F smooth muscle has no sarcoplasmic reticulum
A
false
does have sarcoplasmic reticulum for Ca++ sequestration, but caveoli are the primary means of regulating intracellular Ca++ concentrations…
22
Q
sarcomeres are associated into __
A
myofibrils
23
Q
myofiber
A
membrane bound element of muscle
- syncytium in skeletal muscle
- myocite in smooth and cardiac muscle
24
Q
myocite
A
individual muscle cells in cardiac and smooth muscle
25
T/F myocites exist in skeletal muscle
false?
| no myocites, just syncyctiums of myofibers?
26
how to tell smooth muscle from skeletal muscle
smooth - centra nucleus, no striations
| skeletal - peripheral multinucleated, striations
27
T/F striations are parallel to sarcomere arrangement
false
| striations = alternating A bans and I bands
28
T/F striations are perpendicular to sarcomere arrangement
true
| striations = alternating A bans and I bands
29
how does weight lifting change skeletal muscle?
increased diameter of fibers
30
T/F weight lifting increases the number of myofibers
false
| increases diameter of myofibers
31
T/F a skeletal muscle fiber is typically as long as the whole muscle
true
32
dark band in striation
A band
33
light band in striation
I band
34
dark band in center of light band in striation
Z line
35
light band in center of dark band in striation
H zone
36
dark band in center of light band in center of dark band in striation
M line
37
how many myofibrils in a membrane bound myofiber
hundreds
38
```
T/F from largest to smallest, muscle elements include:
myofiber
myofibril
sarcomere
myofilaments
```
true
39
3 connective tissue investments surrounding muscle tissue
endomysium - surrounds myofiber
perimysium - surrounds fascicles
epimyseium - surrounds multiple fasicles (muscle as a whole), connects muscle to tendon
40
T/F blood vessels can be found in endo, peri, and epimysium
true?
smaller in endomysium
larger in perimysium
any blood vessels in epimysium?
41
T/F adipose and nervous tissue are possible in perimysium
true
42
how does skeletal muscle tissue arise?
```
somite
myotome
myoblasts (muscle progenitor cells)
myocites
functional syncytium
myofibrils
```
43
satellite cells in muscle
within the external lamina outside sarcolemma
| -presumably capable of regenerating myofibers in case of damage
44
within the external lamina outside sarcolemma
| -presumably capable of regenerating myofibers in case of damage
satellite cells in muscle
45
T/F endomysium contains external lamina
true
| external lamina is outside all plasmalemma
46
external lamina of muscle
```
surrounds all plasmalemma
-yes within endomysium
-yes within perimysium
-yes within epimysium
surround ALL PLASMALEMMA
```
47
T/F external lamina = external membrane
true
| same thing
48
this is ~ the basement membrane of muscle
external lamina
49
what are the components of the external lamina?
same as basement membrane
- lamina lucida
- lamina densa
- lamina reticularis (type IV collagen)
50
striated muscle encompasses...
skeletal muscle
| cardiac muscle
51
what muscle types are not striated?
smooth muscle
52
a myocyte that persists outside the sarcolemma of a muscle fiber, but inside the external membrane
satellite cell
53
alpha-actinin
protein of Z line holding actin
54
protein of Z-line holding actin
alpha-actinin
55
myomesin and C-protein
form M line holding myosin together
56
materials that form M line holding myosin together
myomesin and C-protein
57
myomesin
forms M line with C-protein to hold myosin together
58
C-protein
forms M line with myomesin to hold myosin together
59
nebulin and titin
hold myosin to Z-line
60
materials that hold myosin to Z-line
nebulin and titin
61
nebulin
with titin holds myosin to Z line
62
titin
with nebulin anchors myosin to Z line
63
costamere
where myofibrils are bound to plasmalemma by intermediate filaments and dystrophin
64
where myofibrils are bound to plasmalemma by intermediate filaments and dystrophin
costameres
65
dystrophin
protein that binds myofibrils to plasmalemma with intermediate filaments at costameres
66
protein that binds myofibrils to plasmalemma with intermediate filaments at costameres
dystrophin
67
how are sarcomeres anchored within myofiber?
anchored to plasmalemma at costameres by intermediate filaments and dystrophin
68
types of skeletal muscle
type I - red (slower, non-fatigue, aerobic)
type IIa - intermediate
type IIb - white (faster, fatigue, anaerobic)
69
T/F muscle fibers can change type on spectrum from red to white in response to use
true
70
connective tissue connected to external membrane of muscle
endomysium
71
connective tissue fascia that binds the anatomical form of the muscle to the surrounding tissues
epimysium
72
order skeletal, cardiac, and smooth muscle according to size
skeletal (largest)
cardiac
smooth (smallest)
73
T/F cardiac myocytes are much smaller than skeletal muscle fibers but larger than smooth muscle myocites
true
74
how many nuclei in a cardiac myocite
1-2
75
sarcoplasmic cone
lighter area where myofibers bend around centrally located nucleus in cardiac myocyte
76
T/F like skeletal muscle, cardiac myocyte nuclei are squished to perifery
false
| sarcoplasmic cone = lighter area where myofibers bend around centrally located nucleus in cardiac myocyte
77
adjacent myocites are connected electrically through ... and bound physically through ...
gap junctions
| fascia adherens
78
fascia adherens in cardiac muscle tissue
binds cardiac myocites together physically
| intercalated disk
79
modified myocites for conducton of electrical signals through heart
purkinje fibers
| -fewer myofilaments
80
these cardiac myocytes will have fewer myofilaments than others
purkinje fibers
| -specialized for conduciotn
81
intercalated disk
fascia adherens
- connect cytoskeletal actin of joined cells
- cadherins + actin
82
the intercalatd disk (fascia adherens) in cardiac muscle is most similar to what structure in epithelial tissue?
zonula adherens (adherens junction)
- connect cytoskeletal actin of joined cells
- cadherins + actin
83
T/F desmosomes correspond to zonula adherens
false
- desmosomes correspond to macula adherens (spot weld) junctions - cadherins + keratin intermediate filaments
- zonula adherens = cadherins + actin
84
synonym for desmosome
```
macula adherens (spot weld) junctions
-cadherins + keratin intermediate filaments
```
85
evolutionarily oldest form of muscle
smooth muscle
86
dense bodies / dense plaques
anchoring proteins for myofilaments in smooth muscles (homologues of z-lines)
-connected to each other via intermediate filaments
87
involuntary muscle includes...
smooth muscle
| cardiac muscle
88
2 classes of smooth muscle
unitary - acts as one mechanical unit
| multiunit - ~1:1 axon:cell ratio for finer control
89
will the iris have unitary or multiunit smooth muscle?
multiunit
| ~1:1 axon:cell ratio for finer control
90
T/F smooth muscle cells in the uterine myometrium are hormonally responsive and grow up to 200 microns in length during pregnancy
true
91
how are smooth muscle cells in the uterine myometrium hormonally responsive?
grow up to 200 microns in length during pregnancy
92
neuromuscular junction
specialized structure joining nerve axon with muscle
| most specialized in skeletal muscle, but present in rudimentary form in smooth muscle too
93
specialized structure joining nerve axon with muscle
| most specialized in skeletal muscle, but present in rudimentary form in smooth muscle too
neuromuscular junction
94
junctional folds
local invaginations of the sarcolemma underneath the point of contact with the axon, designed to increase surface area and number of ACh receptors
95
local invaginations of the sarcolemma underneath the point of contact with the axon, designed to increase surface area and number of ACh receptors
junctional folds
96
muscle spindles
- sensory structures in muscle to sense position and stretch-state
- composed of modified muscle fibers (bag and chain fibers) with sensory neurons that sense position and stretch and gamma motor neurons that alter sensitivity
- encapsulated by its own perimysium
97
sensory structures in muscle to sense position and stretch-state
muscle spindles
98
composed of modified muscle fibers (bag and chain fibers) with sensory neurons that sense position and stretch and gamma motor neurons that alter sensitivity
muscle spindle
99
bag and chain fibers
modified muscle fibers in a muscle spindle that includes sensory neurons to sense position and stretch and gamma motor neurons to alter sensitivity
100
modified muscle fibers in a muscle spindle that includes sensory neurons to sense position and stretch and gamma motor neurons to alter sensitivity
bag and chain fibers
101
gamma motor neuron
motor neuron specific to muscle spindle to modify sensitivity of sensory neurons to position and stretch
102
motor neuron specific to muscle spindle to modify sensitivity of sensory neurons to position and stretch
gamma motor neurons
103
golgi tendon organ
like a muscle spindle with specialized muscle fibers and sensory and motor neurons
- positioned between muscle fibers and connecting tendon
- primarily associated with reflexive responses of the muscles
104
positioned between muscle fiber and tendon,
| ~like a muscle spindle with specialized muscle fibers and sensory and motor neurons
golgi tendon organ
105
primarily associated with reflexive response of muscles
golgi tendon organ
106
muscle spindle is homologous in structure and function to...
golgi tendon organ
107
golgi gendon organ is homologous in structure and function to...
muscle spindle
108
difference between muscle spindle and goligi tendon organ?
- muscle spindle: specialized muscle fibers and nerves to sense position and stretch, in muscle itself
- golgi tendon organ: specialized muscle fibers and nerves to sense position and stretch, between muscle and tendon, mostly for reflexive response of muscle
109
T/F unitary and multiunit smooth muscle is on somewhat of a spectrum depending on nerve:myocyte ratio
true
110
3 subclasses of muscle
-striated (I,IIA,IIB skeletal; standard, endocrine, conducting cardiac)
-smooth (unitary, multiunit)
single cell (myofibroblast, myoepithelial)
111
how do you tell unitary from multiunit smooth muscle apart on H&E?
very difficult, need to know anatomy
| -perhaps with special nerve stain
112
intracellular actin of neighboring cells meet at ...
zonula adherens
(adherens junctions)
catenin + actin
113
how is actin anchored to dense bodies in smooth muscle?
f-actin tethered to dense bodies by a-actin
114
a-actin
tethers f-actin to dense bodies in smooth muscle
115
T/F there exist smooth muscles that are under voluntary control
false
| smooth muscle Never under voluntary control (by definition, as far as we know..., in humans)
116
between unitary and multiunit smooth muscle, which would you call myogenic and which would you call neurogenic?
unitary - myogenic (single axon many gap juncitons)
| multiunit - neurogenic (axon:myocite ~1:1)
117
iris, erector pilli, large blood vessels, and small airways of the lung contain unitary or multiunit smooth muscle?
multiunit
| fine control
118
do caveoli appear on P or E face in freeze fracture?
both
| endocytosing vesicles will appear similarly on both E and P face
119
T/F caveoli can be associated with cardiac muscle
false
smooth muscle only
-Ca++ release from SR in cardiac initiated by action potential, sarcolemma, T-tubules, sarcoplasmic reticulum
-Ca++ release from SR in sooth muscle initiated by caveoli
120
T/F caveoli can be associated with skeletal muscle
false
smooth muscle only
-Ca++ release from SR in skeletal initiated by action potential, sarcolemma, T-tubules, sarcoplasmic reticulum
-Ca++ release from SR in sooth muscle initiated by caveoli
121
T/F caveoli can be associated with smooth muscle
true
smooth muscle only
-Ca++ release from SER in sooth muscle initiated by caveoli
122
dyad
where t-tubule meets a terminal cisterna of SR in cardiac myocites @ Z-lines
123
where t-tubule meets a terminal cisterna of SR in cardiac myocites @ Z-lines
dyad
124
how many feet in a dyad
2
1 terminal cisterna of SR
1 t-tubule
125
where does a dyad rest on a cardiac myocite?
at Z-lines
126
the specific name for the zonula adherens in cardiac muscle
fascia adherens
127
T/F intercalated disks are composed of gap junctions
false
yes, there are gap junctions there, but gap junctions also appear laterally; the intercalated disk is due to the fascia adherens (cadherins + actin)
128
T/F the t-tubule contains extracellular space
true
129
triad
where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum
-located where I band meets A band (right where it needs to deliver calcium)
130
where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum
triad
| -located where I band meets A band (right where it needs to deliver calcium)
131
located where I band meets A band (right where it needs to deliver calcium)
triad
| where t-tubule meets 2 terminal cisternae of sarcoplasmic reticulum
132
T/F cardiac myocytes are usually binucleated
false
| binucleaton possible, but usually mononucleated
133
cytoplasmic space devoid of myofibrils but full of organelles in cardiac myocyte
sarcoplasmic cone
| -caused because myofibrils spanning entire cardiac myocite must get around nucleus
134
caused because myofibrils spanning entire cardiac myocite must get around nucleus
sarcoplasmic cone
| cytoplasmic space devoid of myofibrils but full of organelles
135
T/F actin filaments span the entire length of a cardiac myosite
```
false
myofibrils (composed of multiple sarcomeres) span the entire length of cardiac myocyte
```
