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Muscle flashcards

Terms in this set (27)

Multinucleate
Having more than one nucleus
Striated
Have visible banding
Endomysium
Encloses a single muscle fiber
Perimysium
wraps around a fascicle (bundle) of muscle fibers
Epimysium
Covers the entire skeletal muscle
Fascia
On the outside of the epimysium
Tendons
Cord-like structures that connect muscle to bone
Aponeurosis
Sheet-like structures that attach muscles indirectly to bones, cartilages, or connective tissue coverings
Involuntary
No conscious control
Sarcolemma
Specialized plasma membrane
Myofibrils
long organelles inside muscle cell; Light (I) bands and dark (A) bands give the muscle its striped appearance
I band
li ght band; Contains only thin filaments; Z disc is a midline interruption
A band
dark band; Contains the entire length of the thick filaments; H zone is a lighter central area; M line is in center of H zone
Sarcomere
contractile unit of a muscle fiber
Myosin filaments
Thick filaments; Composed of the protein myosin, Contain ATPase enzymes, Possess myosin heads, Heads are known as cross bridges when they link thick and thin filaments during contraction
Actin filaments
Thin filaments; Composed of the contractile protein actin, is anchored to the Z disc
Z disc
A midline interruption
Sarcoplasmic reticulum
Specialized smooth endoplasmic reticulum, Stores and releases calcium, Surrounds the myofibril
H zone
a narrow and less dense zone of myosin filaments bisecting the A band in striated muscle—compare m line.
Irritability
(Responsiveness) ability to receive and respond to a stimulus
Contractility
ability to shorten when an adequate stimulus is received
Extensibility
ability of muscle cells to be stretched
Elasticity
ability to recoil and resume resting length after stretching
Neuromuscular junction
Association site of axon terminal of the motor neuron and sarcolemma of a muscle
Neurotransmitter
Chemical released by nerve upon arrival of nerve impulse in the axon terminal
Acetylcholine (ACh)
the neurotransmitter that stimulates skeletal muscle
Synaptic cleft
Gap between nerve and muscle; Nerve and muscle do not make contact; Filled with interstitial fluid
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