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]

What the...

 

[Backlash]

[Ralph voice]My cat's breath smells like cat food.[/Ralph voice]

 

[killa in manila]

thanks alot casual,really helped.

 

[pwr_machine]

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

Still a student...working on a Ph.D. in Human Performance...got a pretty strong ex phys background

 

[louden_swain]

Still a student...working on a Ph.D. in Human Performance...got a pretty strong ex phys background

Fun. . .fun. . . fun

general exams, oral exams, and dissertation.

Do you have a topic for your dissertation?

 

[casualbb]

Speaking of sliding filament theory, this is one of the reasons why you should do static stretches before working out.

There's an optimal length at which there's a good amount of overlap between actin and myosin fibers. Stretching pulls the Z-lines apart, disrupting this optimal distance and reducing voluntary strength.

I just thought of that a sec, figured it was pertinent...

 

[Lord_Suston]

pwr_machine great answer.

I personally like the PEC muscle fiber model myself. ah the power of sodium and calcium....

 

[pwr_machine]

Fun. . .fun. . . fun

general exams, oral exams, and dissertation.

Do you have a topic for your dissertation?

One more year so I'll be picking a topic soon. I'm leaning towards a diseased population...Native Americans and diabetes. I grew up on a reservation with a typical high prevalence of diabetes.

 

[pwr_machine]

pwr_machine great answer.

Thanks!

 

[Lord_Suston]

One more year so I'll be picking a topic soon. I'm leaning towards a diseased population...Native Americans and diabetes. I grew up on a reservation with a typical high prevalence of diabetes.

diebetes is a diseas of lipid and carbohydrate insensitivity. in native american have what is called a thrifty gene, basically stores most nutrients as fat but this leads to obese population in the carb based society we live in. this with a fast absorption rate and insulin spikes is causing a lot of problems

 

[PatsFan34]

Damn, bunch of smart mofo's up in here...up in here!!!