Components of a nerve cell
nerve fiber(inner part)
myelin sheath(insulation)
motor end plate(innervates tissue)
what does membrane potential refer to
the cell is partially positive outside the cell, and partially negative inside the cell
what creates membrane potential
Na+/K+ pump
-Na+ out of cell
-K+ into cell
what happens in the nerve to allow for contraction
-brain stimulates nerve
-membrane becomes more permeable to Na+ which floods in and changes the charge
-Na/K pump reestablishes equalibrium
basic pathway that leads to contraction
brain signal
sarcolema
triad
SR
ca+
troponin
tropomyosin
4 steps of actomyosin complex
relaxation
what is released in the nerve to amplify pulse to muscle fiber
acetyl choline
what is the triad
junction of T-tubules and SR where nerve impulse is transmitted to SR
what signals the SR to release calcium for muscle contraction
impulse reaches the SR depolarizing it
after calcium is released from the SR how does it aid muscle contraction
it binds to troponin complex, causing a conformational shift which allows myosin heads to bind to actin
3 parts of the troponin complex and how they interact with contraction
TaC-binds calcium
TaI- undergoes conformational shift
TaT- controls tropomyosin
4 steps for formation and release of actomyosin complex
1). myosin head binds to actin
2). ADP + P are released causing myosin head to hinge(power stroke)
3). ATP binds to myosin head causing it to disassociate from actin
4). ATP is hydrolyzed and myosin head returns to original position
what segments of the sarcomere disappear when fully contracted
I band
H zone
3 places ATP is required for relaxation after contraction
1). Na+/K+ pump(reestablishing equilibrium)
2). Ca+ pump in SR(return calcium to SR)
3). release myosin head from thin filament
