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Home Q & A Board Biology-Related Homework Help Anatomy and Physiology
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Xplumyumx Xplumyumx
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7 years ago
I know that without them the muscle could not contract. However, I'm confused with the options Im given to answer the question.
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Without t-tubules:
A. Resting muscle may spontaneously contract
B. Activated muscle will not become depolarized
C. Myofibrils will not shorten in activated muscle
D. B&C
E. All of the above
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#1
Educator
7 years ago
Keep this in mind:

T tubules are infoldings of the plasma membrane that encircle the myofibrils and are in contact with the sarcoplasmic reticulum.

Without T tubules, the muscle cell would not be able to contract.

T tubules carry action potentials into the interior of the muscle cell via voltage-gated Na+ and K+ Channels.
Xplumyumx Author
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#2
7 years ago
So it wouldn't be A or E.
No contraction would mean ot wouldnt be depolarized. So it could be B. If no contraction than there's no contraction of the myofibrils, correct? It could be both B and C, so mayne the answer is D?
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#3
Valued Member
7 years ago
D ! the muscle cannot spontaneously contract without Ca into the system.
Orthopedic Physical Therapist 
B.S. Kinesiology and Human Performance
DPT
Xplumyumx Author
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#4
7 years ago
Thank you for your help! Slight Smile
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