Question | Answer |
contractility | the ability of skeletal muscle to shorten with force |
excitability | the capacity of skeletal muscle to respond to a stimulus |
extensibility | the ability to be stretched |
elasticity | ability to recoil to their original resting length after they have been stretched |
what do muscles help produce? | heat, essential for maintenance of normal body temperature |
epimysium | what connective tissue sheath is it that surrounds each skeletal muscle |
fascia | another connective tissue located outside the epimysium, it surrounds and separates muscles |
a muscle is composed of numerous visible bundles called.. | muscle fasciculi |
the muscle fasciculi are surrounded by loose connective tissue called.. | perimysium |
the fasciculi are composed of single muscle cells called.. | fibers |
what does each muscle fiber contain | several nuclei |
each fiber is surrounded by a connective tissue sheath called the.. | endomysium |
the cytoplasm of each fiber is filled with.. | myofibrils |
myofibrils | a threadlike structure that extends from one end of the fiber to the other |
actin myofilaments | thin myofilaments |
what do actin myofilaments resemble | 2 minute strands of pearls twisted together |
myosin myofilaments | thick myofilaments |
what do myosin myofilaments resemble | bundles of minute golf clubs |
what do actin and myosin myofilaments form | highly ordered units called sacromeres |
sacromeres are joined together end to end to form what | the myofibril |
the sacromere is the basic structural and functional unity of the what | the muscle |
eac sacromere extends from one ___ line to another ___ line | Z line |
each z line is an attachment site for what | actin |
the arrangement of actin and myosin give a what appearance | banded |
what is on each side of a z line | an I band |
what does an I band consist of | actin |
the A band extends the length of the what | of the myosin |
it is the _____ central region in each sacromere | darker |
in the center of each sacromere is another light area called the what | the H zone |
what does the H zone consist of | only myosin |
the myosin myofilaments are anchored in the center of the sacromere at a dark staining band called the what | the M line |
the outside of most cell membranes is ____ charged | positively |
the inside of the cell membrane is _____ charged | negatively |
the charge difference across the membrane is called the what | the resting membranepotential |
when a muscle cell is stimulated the membrane characteristics do what | they change breifly |
the brief reversal back of the charge is called the what | the action potential |
motor neurons | are nerve cells that carry action potentials to vthe skeletal muscle fibers |
axons enter the what and branch | the muscle |
each branch that connects to the muscle forms a what | neuromuscular junction |
what else does it form | synapse |
where is the synapse formed | near the center of the cell |
a single motor neuron and all the skeletal muscle fibers it innervates are called a what | a motor unit |
many motor units form a what | a single muscle |
a neuromuscular junction is formed by what | an enlarged nerve terminal resting in an indentation of the muscle cell membrane |