muscle+contraction+6

__**Muscle Contraction**__ __**Sliding Filament Theory:**__ The I and H band become narrower while the A band does not

(NOTE: calcium must be present for this to happen)
 * __Action Potential(Golf Club): ﻿ __**
 * 1) Sodium channel opens up
 * 2) This causes the depolarization of the sarcoma
 * 3) T-tubules bring depolarization into the cell
 * 4) Sarcoplasmic reticulum allows calcium to leak out
 * 5) It then diffuses into the myofilaments
 * 6) Calcium fills space in Tropimon molicules(this alters the shape and position which causes movement of the attached tropamisen molecule)[[image:file:///F:/Anatomy/sliding%20filament.jpg]]
 * 7) Movement of Tropamisen prompts the Myosin head to contact Acton
 * 8) Contact with Acton causes the Myosin head to swivel
 * 9) When the head swivel it pulls the Acton forward
 * 10) The head is bound firmly to Acton (NOTE: If head was not attached to Acton when it swiveled back it will bind will bind to a different Acton molecule)
 * 11) Thick myofilament is pulled by the myosin heads of the tick myofilaments (this means the thick and thin myofilaments are sliding past each other). As the occurse the distance between the z-lines of the sacromere decreaes. As sacromeres get shorter myofibrils shrink, muscle fiber shrink
 * 12) Skeletal muscles relaxes when the nerve impulse stops (no impulse means that the membrane of the sacoplasmice does not allow Ca diffuse out). The Calcuim pump transport Ca back into the call and Ca ions leave the binding cites on the topamine molecules. (Tropamine returns to its original shape and position) So the myosin head is no longer is contact with Acton and therefore the muscle stops contraction.