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MICROSCOPIC ANATOMY OF THE SKELETAL MUSCLE

31 flashcardsby Kennu
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1
what is the typical length of a mature muscle fiber?
10-30 cm
2
what developmental stage does the muscle fiber arises from the fusion of a hundred or more myoblast?
embryonic development
3
each muscle fiber is multinucleited. t/f
true
4
this is the plasma membrane of the muscle fiber and it conducts action potential
sarcolemma
5
these are tiny invaginations of the sarcolemma that tunnels towrds the center of the muscle fiber
transverse tubules
6
transverse tubules are filled with ________
interstitial fluid
7
what are the fx of the transverse tubules?
spreading action potential inside the muscle fiber; ensure all parts of the muscle fiber contracts at the same time
8
this is the cytoplasm of the muscle fiber and it provides energy and oxygen neede for contraction
sarcoplasm
9
what does the sarcoplasm contains?
glycogen, myoglobin, mitochondria
10
these are long, threads contractile organelles inside the sarcoplasm
myofibrils
11
what is the average length of the myofibrils?
2 micrometer (μm)
12
these are responsible for contraction and striations
myofibrils
13
these are network of fluid filled sacs surrounding each myofibril
sarcoplasmic reticulum
14
these are enlarged sacs at the end of the sarcoplasmic reticulum and it stores calclium
terminal cisterns
15
what are the fx of the sarcoplasmic reticulum?
stores ca+ when relaxed; releases ca+ to trigger contraction
16
what is the size of the thin filaments?
8nm in d; 1-2 micrometer in l
17
what are the proteins of the thin filaments?
actin, troponin, tropomyosin
18
what is the size of the thick filaments?
16 nm in d; 1-2 micrometer
19
what is the protein of the thick filaments?
myosin
20
for every thick filaments, there are __ thin filaments
2
21
this the main responsible for muscle contraction
thick filaments
22
this is the contractile unit of a myofibril
sarcomere
23
the sarcomere extends from one __ disc to another __ disc
z disc; z disc
24
the dense protein structure marking the boundaries of the sarcomere
  • z disc
  • a band
  • i band
  • h zone
  • m line
25
this is aka the dark band
a band
26
this is the full length of the thick filaments and is responsible for the dark striations
a band
27
this aka the light band and it passes through the z disc
i band
28
what does the i band contains?
thin filaments
29
this is the middle of the a band and it contains the thick filaments only
h zone
30
what does the h zone contain?
thick filaments
31
this is the supporting proteins in the center of the h zone and it holds teh thick filaments together at the middle
  • z disc
  • a band
  • i band
  • h zone
  • m line
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