M. Phys

M- Line

Stabilizes thick ?lament latticeThicker in Type I vs. Type II3 Components-Creatine Kinase (CK) ~2% Enzyme catalyzes rxn of PCr + ADP ? ATP-CK mostly soluble and associated c H-band-M protein-Myomesin-Myosin-Titin

Smooth Muscle Organization

1. Whole muscle (epimysium) belly2. Muscle Fascicle (perimysium) Bundle of muscle ?bers3. Muscle Fiber (endomysium/ sarcolemma)Muscle cell 4. Myo?brilSarcomeres in series 5. SarcomereZ-disc to Z-disc 6. Myo?lamentsSuch as actin, myosin, titin etc.

Action Potential generated at Axon Hillock

1.Gradual depolarization to threshold2.Rapid rising phase3.Overshoot4.Repolarization-Followed by a brief afterhyperpolarization.

Action Propagation / Myelin

1)Action potential propagation is unidirectional.2)All or none.3)No decrement in AP magnitude.4)Conduction velocity depends on axon diameter and the presence/absence of myelin.5)Myelin is an insulator.6)Myelin is produced by:-CNS: Oligodendrocytes-PNS: Schwann Cells7)Action potential propagation is saltatory 8) At nodes of Ranvier

Activated Nerve Terminal

1) Nerve Impulse2)Voltage gated Ca+ channel opens Ca+->3) Neurotransmitter released

Ligand-gated ion channel

~70 vesicles fuse with presynaptic membrane~6,000 � 10,000 ACh molecules are released/quantal packet (one vesicle)~250,000 AChR?s are opened per AP

Excitation-Contraction (EC) coupling

-AP;s travel in T-tubule @ 7cm/s-Super?cial myo?brils contract ?rst.-Conversion of electrochemical energy into mechanical energy.-AP -- ACh -- AP -- Ca -- Actin/Myosin interaction++