Question:medium
The most common type of calcium channels in skeletal muscle are?
The most common type of calcium channels in skeletal muscle are?
Show Hint
It is the dihydropyridine receptor sitting in the T-tubule.
Updated On: Jun 24, 2026
- T type
- L type
- R type
- N type
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: The dominant calcium channel of skeletal muscle is the L-type, also known as the dihydropyridine receptor packed into the T-tubule walls.
Step 2: Functionally this channel acts as the voltage sensor of excitation-contraction coupling. When the surface action potential spreads down the T-tubule, the L-type channel changes shape and, through a direct physical link, opens the ryanodine receptor to flood the cytosol with calcium from the sarcoplasmic reticulum.
Step 3: The remaining options serve other tissues: T-type channels suit rhythmic, low-threshold firing; N-type and R-type channels dominate presynaptic nerve terminals controlling transmitter release. None of them is the principal skeletal muscle channel.
Step 4: The high concentration of L-type channels in the T-tubule system makes L type the correct choice.
\[\boxed{\text{L type}}\]
Step 2: Functionally this channel acts as the voltage sensor of excitation-contraction coupling. When the surface action potential spreads down the T-tubule, the L-type channel changes shape and, through a direct physical link, opens the ryanodine receptor to flood the cytosol with calcium from the sarcoplasmic reticulum.
Step 3: The remaining options serve other tissues: T-type channels suit rhythmic, low-threshold firing; N-type and R-type channels dominate presynaptic nerve terminals controlling transmitter release. None of them is the principal skeletal muscle channel.
Step 4: The high concentration of L-type channels in the T-tubule system makes L type the correct choice.
\[\boxed{\text{L type}}\]
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