Chapter 9 Part 3 Flashcards
When muscles contract the movable bone, the muscle’s _______ moves toward the immovable bone, the muscle’s _______.
When muscles contract the movable bone, the muscle’s insertion** moves toward the immovable bone, the muscle’s **origin.
_______ are densely packed, rodlike contractile elements made of sarcomeres.
Myofibrils are densely packed, rodlike contractile elements made of sarcomeres.
What are myofibrils?
Myofibrils are densely packed, rodlike contractile elements made up of sarcomeres
______ are the smallest contractile unit of a muscle.
Sarcomeres are the smallest contractile unit of a muscle.
What is the term for the region of a myofibril between two successive Z discs?
Sarcomere
Desribe actin and myosin
Actin → thin filament
Myosin → thick filament
______ extend the entire length of an A band.
Thick filaments extend the entire length of an A band.
______ extend across the I band and partway into the A band.
Thin filaments extend across the I band and partway into the A band.
What are coin-shaped sheet of proteins (connectins) that anchors the thin filament and connects myofibrils to one another?
Z-disc
M lines appear darker due to the presence of the protein _______.
Desmin
What functions in the regulation of intracellular calcium levels?
sarcoplasmic reticulum
What penetrates into the cell’s interior at each A band-I band junction?
T tubules
Briefly describe what a triad is…
A triad is a pair of terminal cisternae and one T tubule
Linking the electrical signal to the contraction is _______.
Linking the electrical signal to the contraction is excitation-contraction coupling.
What are skeletal muscles stimulated by?
Skeletal muscles are stimulated by motor neurons of the somatic nervous system.
