Lec 9- Skeletal Muscle Structure Flashcards
Muscle Fiber
Attaches to the skeleton.
Relatively large, elongated, and cylinder shape.
Sarcolemma
the fine transparent tubular sheath which envelops the fibers of skeletal muscles.
Sarcoplasma
Sarcoplasm is the cytoplasm of a myocyte.
Myofibril
Specialized contractile elements that constitute 80% of the volume of the muscle fiber.
Myofilament
Thick and thin; cytoskeletal elements
Sarcomere
Area between two Z line; which is the functional unit of a skeletal muscle.
T-tubule
Runs perpendicular from the surface of a muscle cell membrane in the central portions of the muscle fiber.
Somatic motor neuron
Somatic motor neurons originate in the central nervous system, project their axons to skeletal muscles (such as the muscles of the limbs, abdominal, and intercostal muscles), which are involved in locomotion.
Motor end plate
Neuromuscular junctions, also called motor end plates, are specialised chemical synapses formed at the sites where the terminal branches of the axon of a motor neuron contact a target muscle cell.
Terminal button
A motor neuron’s enlarged knob-like ending that terminates near a skeletal muscle fiber and releases ACh in response to an action potential in the neuron.
DHP (dihydropyridine) receptor
(a) they function as the voltage sensor which undergoes fast transition to control release of calcium from sarcoplasmic reticulum.
(b) they provide the conducting unit of a slowly activating L-type calcium channel.
Troponin
Thin filament component.
3 subunits.
Tropomyosin
Thin filament component.
threadlike protein that covers actin sites.
SR (sarcoplasmic reticulum)
A membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+).
Mysoin
thick filament
