Glossary of Muscular System Test

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

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