山东大学：《医学生理学 Medical Physiology》课程教学资源（PPT课件讲稿，人体生理学 Human Physiology）Chapter 2 Function of the Cell section 3 Muscle Contraction

Section 3 Muscle Contraction

Section 3 Muscle Contraction

Classification of the muscle According to the structure Striated Muscle Smooth muscle According to the nerve innervation Voluntary Muscle, Involuntary Muscle >According to the Function: Skeletal Muscle Cardiac Contraction. Smooth Muscle

3 Classification of the Muscle ➢According to the structure: Striated Muscle, Smooth Muscle ➢According to the nerve innervation: Voluntary Muscle, Involuntary Muscle ➢According to the Function: Skeletal Muscle, Cardiac Contraction, Smooth Muscle

Skeletal muscle Cardiac Muscle Smooth Muscle

4 Skeletal Muscle Cardiac Muscle Smooth Muscle

I Signal Transmission Through the neuromuscular junction

I Signal Transmission Through the Neuromuscular Junction

Skeletal muscle innervation otor Control Path of action neuron potential Neuromuscular Axon junction Excitation-contraction Myofibril Excitation Motor end plate Calcium Energy . Vtriggers Synaptic terminal Thick-thin filament interaction□ Mitochondrion Tmmmmmmm Muscle fibe Myofibril Muscle fibe x leads to Tension+

6 Skeletal Muscle Innervation

Illustration of the neuromuscular Junction (NMD) Motor neuron fiber Nerve fiber branches Muscle fiber nucleus Motor end plate Myofibril of muscle fiber e Mitochondria Synaptic vesicles Synaptic cleft Folded sarcolemma onn Motor end plate

7 Illustration of the Neuromuscular Junction (NMJ)

New lon 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 Motor ne uscle fiber nucleus Myofibril of muscle fiber Motor end plate

8 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

Nerve Terminal ca2+ channels Structurally similar to Nat channels Functionally similar to Nat channels except >activation occurs at more positive potentials >activation and inactivation much slower than Na channels

9 Nerve Terminal Ca2+ channels ➢Structurally similar to Na+ channels ➢Functionally similar to Na+ channels except ➢activation occurs at more positive potentials ➢activation and inactivation much slower than Na+ channels

Neuromuscular transmission Axon Axon terminal Skeletal muscle

10 Neuromuscular Transmission Skeletal Muscle Axon Axon Terminal

Neuromuscular Depolarization Transmission potestiacashadeels t Step by step axon terminal Look here

11 Neuromuscular Transmission: Step by Step Nerve action potential invades axon terminal - - + - - - - - + + + + + + + - - - + + Depolarization of terminal opens Ca channels Look here + +