Muscular system depolarization/repolarization/hyperpolarization

[serenityangel]

I'm currently taking a six-week AP I summer class. Our muscular system exam is on Monday, and I've been studying my butt off. For the life of me though, I just cannot understand the depolarization/repolarization/hyperpolarization stuff. I get the sliding filament model and cross-bridge cycling. Anyone know a website or something that could help me understand it? To be more specific, I don't understand these questions in our study guide.

What could change dramatically the potential across the plasma membrane? Ex: permeability to sodium ions? What would make it increase?

What would happen if you had increased potassium concentration outside the plasma membrane?

For the second one, someone told me hyperpolarization. I just don't understand why. Thanks for any help.

[Birry]

These videos might help with your exam:

Khan Academy: Myosin and Actin

Khan Academy: Electrotonic and Action Potentials

Khan Academy: Anatomy of a muscle cell

Khan Academy: Role of the Sarcoplasmic Reticulum in Muscle Cells

Khan Academy: Tropomyosin and troponin and their role in regulating muscle contraction

Khan Academy: Sodium Potassium Pump

Khan Academy: Correction to Sodium and Potassium Pump Video

[Cherish]

http://www.edgeroamer.com/sweethaven/medical/Physiology/HumPhys02.asp?iNum=0005

http://www.innerbody.com/image/musc02.html

http://faculty.alverno.edu/bowneps/muscle/mindex.htm

http://www.cbu.edu/~aross/APIhome.htm

http://www.mfi.ku.dk/ppaulev/chapter2/Chapter%202.htm

[serenityangel]

Thank you so much.