muscle Flashcards
(83 cards)
1
Q
Skeletal and cardiac muscle appears
A
striated
2
Q
Cardiac and smooth muscle is innervated by
A
autonomic NS
3
Q
Smooth muscle lines the
A
hollow walls of organs
4
Q
smooth muscle is responsible for
A
GI motility
constriction of blood vessels
uterine contractions
5
Q
somatic neurons stimulate
A
skeletal muscle
6
Q
Tendons
A
muscle attached to bones
7
Q
tendons are composed of
A
strong connective issue which contains primarily collagen
8
Q
muscle contracts: the ______ is brought closer to the _____
A
insertion point is brought closer to the origin
9
Q
skeletal muscle is composed of muscle &
A
connective tissue
10
Q
what is the function of connective tissue in skeletal muscle
A
Connective Tissue (CT) holds the contractile tissue together in bundles called fasicles to allow flexibility
11
Q
Muscle fiber is a
A
single skeletal muscle cell
12
Q
Skeletal muscle cells are
A
multinucleated synctia formed by the fusion of individual cells during development
13
Q
skeletal muscle cells are innervated by
A
a single nerve ending
14
Q
all skeletal muscle cells are innervated by ____ motor neurons
A
all skeletal muscle cells are innervated by __somatic__ motor neurons
15
Q
Somatic motor neurons release _______ @ NMJ
A
ACh
16
Q
the difference in regulation is the ______ of the signal
A
the difference in regulation is the timing of the signal
17
Q
Sacrolemma is the
A
myofiber cell membrane
18
Q
the sacrolemma differs from the Plasma membrane in that
A
it has an additional layer of polysaccharide & collagen
19
Q
sacrolemma’s additional layer helps
A
fuse with the tendon fibers
20
Q
myofibrils are units within each
A
myofiber
21
Q
myofibrils in the muscle cell is like a specialized
A
organelle
22
Q
myofibril is responsible for the
A
striated appearance of a muscle cell
the contractile force
23
Q
what proteins are responsible for generation of muscle contraction in the myofibril
A
actin and myosin
24
Q
actin
A
thin filaments
25
myosin
thick filaments
26
striated appearance of skeletal muscle is due to
overlapping arrangement of bands of thick and thin filaments in sacromeres
27
myofibril composition of sacromeres is
myofibril is composed of many sacromeres aligned end-to-end
28
each sacromere is bound by 2
z lines
29
thin filaments attach to ____
| thin filaments ___ with thick filaments in the middle of the sacromere
z lines
| overlap with thick filaments
30
thick filaments are _____ to z lines
NOT ATTACHED
31
I bands contain only
thin filaments
32
A bands
full length of thick
| includes overlapping region
33
H zone
only thick
| seen in resting sacromere
34
Mnemonic
| Z line
Z line denotes boundarieZ of Sacromere
35
Mnemonic
| M line
M line in the Middle
36
Mnemonic
| H is
H is thick so thick filaments
37
Mnemonic
| I is
I is thin so thin filaments
38
Mnemonic
| A is
A is thick And thin
39
Mnemonic to help remember the order
"Zee Intelligent Animal Has Muscle"
Z-I-A-H-M-H-A-I-Z
M is symmetry point
40
contraction occurs when
thick and thin slide across each other
41
contraction _____ z lines ____ to each other ---> ____ length of muscle cell
contraction _draws_ z lines _close_ to each other ---> _shortening_ length of muscle cell
42
where does the energy for filament sliding come from
ATP hydrolysis
43
which enzyme uses ATP hydrolysis
myosin uses ATP hydrolysis to generate movement
44
a myosin monomer is composed of a
head and a tail
45
myosin head attaches to _____ when attached it is referred to as ______
specific site on actin - myosin binding site
| when attached it is referred to as cross bridge
46
filament sliding
1. cross bridge formation
2. power stroke
3. release of actin
4. ATP hydrolysis
47
power stroke
myosin head moves to lower E. conformation --> pulls actin toward center of sacromere ---> release of ADP
48
each step of filament sliding theory and what is bound to myosin
1. myosin binds to actin. Has ADP + Pi
2. myosin bound to actin. releases ADP.
3. ATP binds to myosin. myosin releases actin
4. ATP hydrolysis --> myosin head to cock into high energy conformation
49
ATP is required for
myosin to release actin
50
when does myosin hydrolyze ATP
when it is not bound to actin and to move it forward into the high energy conformation
51
in a myofiber contraction only occurs when cytoplasmic concentration of
calcium increases
52
thick filaments
contain tropoin-tropomyosin complex
53
when no Calcium is present
tropoin-tropomyosin complex prevents
54
tropomyosin
blocks all myosin binding sites
long fibrous proteins
winds along actin polymer
55
tropoin
calcium binds to tropoin
globular protein
bound to tropomyosin
56
calcium binds to ______ --> _________ change
calcium binds to tropoin --> conformational change
57
conformational change results in __________
conformational change causes tropomyosin to move out of the way
58
in summary binding of calcium to ______ causes _____ change which results in ______ moving and allowing for _________ to attach to _____ resulting in the ______.
in summary binding of calcium to _tropoin_ causes _conformational change_ change which results in _tropomyosin_ moving and allowing for _myosin head_ to attach to _actin_ resulting in the _filament_sliding_.
59
NMJ is synapse between axon and ______.
| NMJ structure is a ______
myofiber
the structure is a long trough/invagination (infolding)
NOT a single point
60
What is the purpose of the NMJ being a long trough?
the purpose is to allow neuron to depolarize a large region of the postsynaptic membrane at once
61
postsynaptic membrane is the _______
motor end plate (myofiber cell membrane)
62
What neurotransmitter is released at the NMJ?
ACh
63
chemical synapse
AP arrives @ axon --> triggers opening of Volt. Gated Calcium channels --> increase in calcium in the cell ---> release of ACh
64
post synaptic membrane has ___ receptors which are _______ channels
post synaptic membrane has _ACh_ receptors which are _ligand gated sodium _ channels
65
since the myofiber is very thick AP on its surface will not depolarize the interior. Thus the solution was to
have deep invaginations of cell membrane --> allow AP to travel to thick of cell
66
what are the deep invaginations of the myofiber membrane called?
T tubules
67
Sacroplasmic reticulum
specialized membrane in myofiber
| specialized smooth endoplasmic reticulum
68
Sacroplasmic reticulum contains _____ channels
Sacroplasmic reticulum contains _V.G. Calcium_ channels --> allow Calcium to rush out of the S.R. into the sacroplasm
69
NS can force increase in contraction by 2 means which are
1. motor unit recruitment
| 2. frequency summation
70
describe
| 1. motor unit recruitment
1. motor unit recruitment group of myofibrils innervated by single motor neuron's axon
71
describe
| 2. frequency summation
2. frequency summation - if insufficient time for the calicum to be sequesterd by the SR then 2nd contraction builds on the first
72
for f. summation to occur the amount of time must be greater than the ________ but also less than the time for _______
for f. summation to occur the amount of time must be greater than the ___refractory period___ but also less than the time for __calcium to return to low resting potential___
73
muscles have a lot of what organelle
highly aerobic with lots of mitochondria
74
myoglobin
Role is an O2 reserve (takes O2 from Hemoglobin and releases it as needed)
similar to 1 subunit of Hemoglobin
globular protein
75
prolonged contraction leads to
anaerobic respiration --> lactic acid --> blood --> decrease in pH ---> picked up by the liver ---> pyruvate
76
anaerobic respiration --> _____ --> blood --> _____ in pH ---> picked up by the ____ ---> _____
anaerobic respiration --> lactic acid --> blood --> decrease in pH ---> picked up by the liver ---> pyruvate
77
Differences between cardiac versus skeletal muscle
1. SYNCYTIUM
- Smooth muslce is a STRUCTURAL syncytium (fusion of individual muscle cells forming multinucleated cell)
- Cardiac is a FUNCTIONAL syncytium (cardiac cells are connected by intercalated discs)
2. Cardiac muscle cells are each connected to several neighbors by intercalated disks
3. Cardiac muscle contraction does NOT depend on stimulation by motor neurons
- ACh is inhibitory
4. AP in cardiac muscle depends on BOTH voltage-gated sodium channels (fast channels) AND on voltage-gated calcium channels (slow channels)
78
function of intercalated disk
gap junctions
which allow AP propagation throughout the entire heart without allowing nuclei and cytoplasmic contents to be shared (only small ions can pass)
79
Similarities between cardiac versus skeletal muscle
1. both are striated
2. thick and thin filaments organized into sacromeres.
3. T tubules
4. tropoin-tropomyosin regulated contraction in the same way
5. length-tension relationship is the same though MORE significant in CARDIAC.
80
structural syncytium
is a multinucleated cell that results from multiple cell fusions of uninuclear cells
81
Similarities between smooth and skeletal muscle
1. contraction accomplished by actin & mysoin filament sliding
2. 4 step contracile cycle
3. contraction triggered by increase in calcium
4. Do not branch
82
Differences between smooth and skeletal muscle
1. Narrower & shorter
2. No T tubules
3. only 1 nucleus / cell. connected to neighbors by gap junctions. FUNCTIONAL syncytia
4. thick and thin NOT organized into SACROMERES. DISPERSED in cytoplasm
5. Tropoin-tropomyosin NOT present. Contraction is regulated by CALMODULIN (binds to Ca) myosin light chain kinase (MLCK)
6. Smooth muscle SR poorly developed. cell relies heavily on extracellular calcium
7. AP varies based on location on smooth muscle (some have no sodium channels)
8. Smooth muscle must sustain longer contractions. AP similar to cardiac
9. Smooth muscle has fluctuating resting potential - "slow waves"
10. innervated by motor neurons bur are autonomic motor neurons
83
calmodulin myosin light chain kinase (MLCK):
| Calcium binds to _______ --> activates _____ --> ______ myosin --> _____ myosin
Calcium binds to _calmodulin__ --> __activates MLCK__ --> __phosphorylates__ myosin --> __activated__ myosin
