sliding fillament theory

[killa in manila]

can someone explain what does the sliding fillament theory means?wanna make sure i fully understand it. thanks

 

[casualbb]

Here's a close up of a sarcomere (contractile unit):

Sliding Filament theory
The Sarcomere shortens as a result of Z-lines moving closer together. Myosin heads attach to actin filaments and asynchronously pulling (power strokes) the actin across myosin. The I band and H zone will converge as actin is pulled, but A band stays the same, as it is comprised of stationary myosin filament

Two proteins, troponin and tropomyosin are important when discussing excitation-contraction (EC) coupling, the PNS trigger of muscle contractions.

Definitions:
-The I-band is the sections where only actin (thin filaments) are seen.
-The A-band is the region where myosin is seen with some overlap of actin.
-H-zone is middle of of A-band, denotes area where only myosin is present.
-The M-line is in the center, is it where myosin anchors for the subsequent pulling.

Anything else?

 

[PatsFan34]

Great post casualbb, haven't seen that diagram since college...good shit man!!!

 

[Lord_Suston]

but the true question for you is how is ATp use in the muscle fiber in conjuction with the sarcoplasmic reticulum. and what wjould cause a depolrization of the contracted muscle fiber????


lol, good to be a bio major sometimes

 

[PatsFan34]

but the true question for you is how is ATp use in the muscle fiber in conjuction with the sarcoplasmic reticulum. and what wjould cause a depolrization of the contracted muscle fiber????


lol, good to be a bio major sometimes

We're gonna have some good science battles, I'm gonna lose horribly because I never went to class, oh well

 

[louden_swain]

casuallbb,

I am impressed with your knowledge in regards to the science of training. . . are you studying health and sport sciences in school?

 

[pwr_machine]

but the true question for you is how is ATp use in the muscle fiber in conjuction with the sarcoplasmic reticulum. and what wjould cause a depolrization of the contracted muscle fiber????


lol, good to be a bio major sometimes

1) an action potential causes the release of Ach at the synapse of the neuromuscular junction (transition from nerve to a muscle)

2) binding of Ach to receptors triggers the opening of Na 2+ gates which leads to an action potential

3) the action potential spreads along sarcolemma and enters fiber via t-tubules

4) action potential triggers the release of Ca 2+ from the SR

5) Ca 2+ binds to troponin C which leads to the sliding filament theory and the muslce contracts:

ATPase on the myosin head hydrolyzes ATP to ADP + phosphate; energy released cocks myosin head

When Ca 2+ is released from SR, it binds to troponin C and moves tropomyosin out of the way

myosin head binds to actin and causes head to pivot and move actin toward the m-line (power stroke)

ADP is released from myosin head

binding of new ATP to myosin head allows detachment of myosin head from actin and the cycle is repeated

6)to end the contraction, Ca 2+ is pumped back into SR

Science? Nah, fun stuff.

 

[PatsFan34]

You must have you bio book out cause there's no way you remembered all that in such great detail!!!

 

[casualbb]

lol all that (including the picture) was out of my NASM education info. They're more in-depth than I expected on the physiology.

I'm actually a psychology major but I'm also taking the pre-med classes (bio, chem, organic chem, etc etc)

It's good that people know this stuff. (btw, pwr_machine wins )

 

[PatsFan34]

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