Contraction of Skeletal Muscle课件.ppt

Section 4
Contraction of Skeletal Muscle
40 % of the body: skeletal muscle
10% of the body: smooth and cardiac muscle
Classification of the Muscle:
According to the structure: Striated Muscle, Smooth Muscle
According to the Function: Skeletal Muscle, Cardiac Muscle, Smooth Muscle
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
transmission of AP on nerve fiber
transmission of excitation in Neuromuscular Junction
transmission of AP in fibers (local current)
Excitation-Contraction Coupling
The Sliding Filament of Muscle Contraction
一、contraction of skeletal muscle
Illustration of the Neuromuscular Junction (NMJ)
neuromuscular transmission
Neuromuscular Junction
Each nerve ending makes a junction called the neuromuscular junction, with the muscle fiber near its midpoint. There is only one such junction per muscle fiber.
Motor end plate: The nerve fiber forms plex of branching nerve terminals that invaginate into the surface of the muscle fiber but lie outside the muscle fiber plasma membrane. The entire structure is called motor end plate.
1. The structure of neuromuscular junction:
⑴prejunctional membrane:
①synaptic vesicle: ACh;
② Voltage-gated Ca2+ channel ;
⑵junctional cleft:
munication with extracellular fluid;
⑶postjunctional membrane:endplate membrane,①N2-Ach receptor;② AChE;
New Ion Channel Players
Voltage-gated Ca2+ channel
in presynaptic nerve terminal
mediates neurotransmitter release
Nicotinic Acetylcholine Receptor Channel
in muscle neuromuscular junction (postsynaptic membrane, or end plate)
mediates electrical transmission from nerve to muscle