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31 Cards in this Set
- Front
- Back
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What are the 4 main functional characteristics of skeletal muscle?
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1. Contractibility
2. Excitability 3. Extensibility 4. Elasticity |
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What causes the appearance of striations?
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The arrangement of thick and thin myofilaments
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What is the all or none law of muscle contraction?
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If a stimulus causes one member of a motor unit to contract then all members of THAT motor unit will contract and they will do so maximally
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The muscle is NOT shortening...
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isometric
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You are able to shorten the muscle to cause movement...
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isotonic
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The anatomical unit of skeletal muscle is...
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the sarcomere
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the functional unit of skeletal muscle is...
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a motor unit
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treppe is...
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the warm up period in muscles, where you get a stair step appearance with out changing the voltage
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what would happen if one's body produced a protein antibody that mimicked ACh but didnt open the pores?
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your muscles would not contract. the disease is called myasthenia gravis (grave disease)
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What is motortone?
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aka neuromuscular spindle...it is responsible for keeping the correct width of the sarcomere
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What is the job of a motor neuron?
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It carries messages to the muscle
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What is the job of a sensory neuron?
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it carries messages away from the muscle and to the brain/spinal cord
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What is the perimysium?
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there is a perimysium that surrounds each fascile in a skeletal muscle
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what is a fascicle?
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a fascicle is a group of muscle fibers
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What is the epimysium?
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it is the outermost connective tissue, it covers the skeletal muscle
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The nucleus of a muscle cell is...
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eccentrically located
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What is the endomysium?
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an envelope that seperates muscle fibers
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What is the sarcolemma?
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It covers one muscle fiber, it is found just under the endomysium
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What is a myofibril?
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It is a subunit of a muscle fiber
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What is a muscle fiber(cell)?
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it is a subunit of a fascicle...many muscle fibers create ONE fascicle
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What is a myofilament?
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It is a subunit of a myofibril
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What is the sarcolemma equivalent to?
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a cell membrane
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What are the 2 structures that sarcomplasmic reticulum take?
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1. cistern
2. tubular portion/fenestrated window |
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What is the purpose of the cistern?
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it is the bag like portion and it is loaded with calcium ions when relaxed
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What is the purpose of the tubular portion of the sarcoplasim reticulum?
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it connects one cistern to another
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What types of myofilaments make up a myofibril?
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Thick and thin myofilaments
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What is the sarcomere?
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it is the area(on a myofibril)between the z-discs...so there are both thick and thin myofilaments
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What is the A band?
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it is the area of overlap between thick and thin myofilments
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What is the H zone?
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it is the area of thick myofilaments...this area becomes smaller as the muscle contracts
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What is the I band?
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where there are only thing myofilaments
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What is the z-disc?
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it is connective tissue, a plate in the form of a disc...the thin myofilaments attatch to the z-line
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