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-   -   T tubule triad structure! (https://www.usmle-forums.com/usmle-step-1-forum/3296-t-tubule-triad-structure.html)

Kabutar111 07-15-2010 12:54 PM

T tubule triad structure!
 
SOMEONE EXPLAIN---two T tubule lies between the two cisternae of the sarcoplasmic reticulum to form a triad , how does it form a triad?:redcheeks;

ecgram 07-15-2010 01:09 PM

its T tubule invagination along with the 2 cisternae (3 structures) form the triad
in skeletal muscle, where as in cardiac muscle only 1 cisternae along with t tubule form the diad

hope u got it

Kabutar111 07-15-2010 01:27 PM

thx
 
Quote:

Originally Posted by ecgram (Post 12009)
its T tubule invagination along with the 2 cisternae (3 structures) form the triad
in skeletal muscle, where as in cardiac muscle only 1 cisternae along with t tubule form the diad

hope u got it

read your comment saw the pics. understood.
THANKS :notsure:
one more thing-
function of t-tubule is to open Ca channel in cisternae why is invaginated as the both are located around the muscle fibre?

Seetal 07-15-2010 04:31 PM

hi kabutar111,

it is invaginated because with the NTs ACh, the muscarinic receptors at the NMJ are triggered n this causes release of Ca2+ to cause muscle contractions. without a stimulation n also with depletion of ATP, muscle contractions do not occur. which is y in myasthenia gravis, where the ACh receptors are blocked by autoantibodies, the muscles become paralyzed.:)

Kabutar111 07-15-2010 05:23 PM

Quote:

Originally Posted by Seetal (Post 12028)
hi kabutar111,

it is invaginated because with the NTs ACh, the muscarinic receptors at the NMJ are triggered n this causes release of Ca2+ to cause muscle contractions. without a stimulation n also with depletion of ATP, muscle contractions do not occur. which is y in myasthenia gravis, where the ACh receptors are blocked by autoantibodies, the muscles become paralyzed.:)

hello seetal,

i understand what you explain but my question is since t tubule is simply a invagination of plasma membrane and neuromuscular at plasma membrane is already in contact with terminal cisternae as it is located just under it why we need an invagination into muscle fibre. unless cisternae are present in middle of muscle fibre too?????


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