sehs topic 4.1 neuromuscular function. label a diagram of a motor unit foundation required: a motor...
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SEHS Topic 4.1 Neuromuscular Function
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Label a diagram of a motor unit• Foundation required:• A motor unit is made up of a motor neuron and all
of the skeletal muscle fibers innervated by that axon.
• What’s neuron? • It’s the functional unit of the nervous system (a.k.a.
a nerve cell)
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Cont’d• http://
www.getbodysmart.com/ap/muscletissue/nervesupply/motorunit/tutorial.html
• The large and complex terminal formation by which the axon of a motor neuron establishes synaptic contact with a striated muscle fiber
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Cont’d• Label this: use the following word bank: tranverse(t)
tubule; axon; synaptic vesicle containing neurotransmitters; synapse; sarcolemma; motor end plate; sarcoplasmic reticulum; neuromuscular junction
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Explain the roles of neurotransmitters (NTs) in stimulating muscle contraction
• What are neurotransmitters (NTs)?• Endogenous chemicals that transmit signals from a
neuron to a target cell across a synapse. • They are packaged into synaptic vesicles clustered
beneath the membrane in the axon terminal, on the presynaptic side of a synapse.
• They are released into and diffuse across the synapse (a.k.a. synaptic cleft), where they bind to specific receptors in the membrane on the postsynaptic side of the synapse
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Cont’d• The key NTs for skeletal muscle contraction include”• Acetylcholine (ACh) and cholinesterase
• In the peripheral nervous system, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system.
• When acetylcholine binds to acetylcholine receptors on skeletal muscle fibers, it opens gated sodium channels in the cell membrane.
• Sodium ions then enter the muscle cell, initiating a sequence of steps that finally produce muscle contraction.
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Cont’d
• So what happens after a motor neuron has been stimulated by Ach?
• In biochemistry, cholinesterase is a family of enzymes that catalyze the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activation
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Cont’d: it essentially terminates synaptic trasmission
• It is also know as a: degradation enzyme
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Explain how skeletal muscle contracts by the SLIDING FILAMENT THEORY
• Foundation 1:• Muscle structure (review in part):
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Cont’d: functional contractile unit: the sarcomere
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Animations
• http://www.youtube.com/watch?v=EdHzKYDxrKc
• http://www.liquidjigsaw.com/science/animation/animations/bigpicture/muscle-contraction.html
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Explain how slow and fast twitch muscle fibers differ in structure and function
• Most of us have a 50%-50% make-up of slow vs. fast twitch muscle fibers. Some of their functions and features are shown below and on the next slide.
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Cont’d – A more inclusive table
• Exercise/sports types: ____________ ______________ ________________