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the muscular system
Question | Answer |
---|---|
the ability of skeletal muscle to shorten with force | contractility |
the capability of skeletal muscle to respond to a stimulus | excitability |
the ability to be stretched | extensibility |
ability to recoil to their original resting length after they have been stretched | elasticity |
help to produce heat essential for maintenance of normal body temperature | muscles |
each skeletal muscle is surrounded by a connective tissue sheath called the | perimysium |
another connective tissue located outside the epimysium | fascia |
surrounds and separates muscles | fascia |
a muscle is composed of numerous visible bundles called | muscle fasciculi (fascicle) |
muscle fasciculi are surrounded by loose connective tissue called the | perimysium |
the fasciculi are composed of single muscle cells called | fibers |
each fiber is a | single cylindrical cell containing several nuclei |
each fiber is surrounded by a connective sheath called the | endomysium |
the cytoplasm of each fiber is filled with | myofibrils |
a thread like structure that extends from one end of the fiber to the other | myofibrils |
what two kinds of protein fibers do myofibrils consist of | actin myofilaments and myosin myofilaments |
thin myofilaments | actin |
thick myofilaments | myosin |
actin and myosin myofilaments form highly ordered units called | sarcomeres |
sarcomeres are joined end to end to form the | myofibril |
the ________ is the basic structural and functional unit of the muscle | sarcomere |
each sarcomere extends from | one z line to another z line |
the arrangement of actin and myosin give a | banded appearance |
the i band is ______ and contains _______ | light and actin |
the a band extends the length of the | myosin |
the a band is | darker |
in the center of each sarcomere is a light area called | the H zone |
the H zone consists of only | myosin |
the myosin myofilaments are anchored in the center of the sarcomere at a dark staining band called | the M line |
the outside of most cell membranes is | positively charged |
the inside of cell membranes is | negatively charged |
the charge difference across the membrane is called the | resting membrane potential |
the brief reversal back of the charge is called | action potential |
nerve cells that carry action potentials to skeletal muscle fibers | motor neurons |
each branch that connects to the muscle forms a ______ near the center of the cell | neuromuscular junction or synapse |
a single muscle neuron and all the skeletal muscle fibers it innervates are called | a motor unit |
__________ is formed by an enlarged nerve terminal resting in an indentation of the muscle cell membrane | a neuromuscular junction |
the enlarged nerve terminal is the | presynaptic terminal |
the space between the presynaptic terminal and the muscle cell is the | synaptic cleft |
the muscle fiber is the | postsynaptic terminal |
each presynaptic terminal contains __________ that secrete a neurotransmitter | synaptic vesicles |
synaptic vesicles secrete a neurotransmitter called | acetylcholine |
muscle cell is rapidly broken down by an enzymes called | acetylcholinesterase |
occurs as actin and myosin myofilaments slide past one another causing sarcomere s to shorten | muscle contraction |
the sliding of actin myofilaments past myosin myofilaments during contraction is called | sliding filament mechanism |
a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers | muscle twitch |
a muscle fiber will not respond to stimulus until that stimulus reaches a level called _________ at which point the muscle fiber will contract maximally. | threshold |
muscle fibers maximally contracted | all-or-none response |
the time between application of a stimulus to a motor neuron and the beginning of a contraction is the | lag phase |
time of contraction | contraction phase |
time during which muscles relax | relaxation phase |
where the muscle remains contracted without relaxing | tetany |
the increase in number of motor units being activated is called | recruitment |
__________ is needed for energy for muscle contraction | ATP (adenosine triphosphate) |
ATP is 1) 2) | 1) produced in the mitochondria 2) short lived and unstable |
it is necessary for muscle cells to constantly produce | ATP |
when at rest they cant stockpile ATP but they can store another high-energy molecule, called | creatine phosphate |
without oxygen | anaerobic respiration |
with oxygen | aerobic respiration |
the ____________ is the amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells. | oxygen debt |
results when ATP is used during muscle contraction faster than it can be produced in the muscle cells | muscle fatigue |
the length of the muscle does not change, but the amount of tension increases during the contraction process | isometric |
the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes | isotonic |
costant tension produced by the muscles of the body for long periods of time | muscle tone |
contract quickly and fatigue quickly and fatigue quickly | fast-twitch fibers |
contract more slowly and are more resistant to fatigue | slow-twitch fibers |
the points of attachment of each muscle are its | origin and insertion |
the ________ is the most stationary end of the muscle | origin |
the __________ is the end of the muscle undergoing the greatest movement | insertion |
the portion of the muscle between the origin and the insertion is the | belly |
muscles that work together to accomplish specific movements are called | synergists |
muscles that work in opposition to one another are called | antagonists |
among a group of synergists, if one muscle plays the major role in accomplishing the desired movement, it is the | prime mover |
muscles are named according to their | location, size, orientation of fibers, shape, origin, insertion, and function |
raises eyebrows | occipitofrontalis |
closes the eyelids and causes " crows feet" wrinkles in the skin at the lateral corners of the eye | orbicularis oculi |
puckers the lips | orbicularis oris |
flattens the cheeks trumpeter's muscle | buccinator |
kissing muscles | orbicularis and buccinator |
smiling muscle | zygomatius |
sneering | levator labii superioris |
frowning | depressor anguli oris |