Question | Answer |
the ability of skeletal muscle to shorten with force | contractility |
the capacity of skeletal muscle to respond to stimulus | excitability |
the ability to be stretched | extensibility |
ability to recoil to original resting length after being stretched | elasticity |
muscles help to... | produce heat essential for maintenance of normal body temperature |
each skeletal muscle is surrounded by a connective tissue sheath called the... | epimysium |
what is another connective tissue located outside the epimysium? | fascia |
what surrounds and separates the muscles? | fascia |
a muscle is composed of numerous visible bundles called... | muscle fasciculi (fascicle) |
fasciculi are surrounded by loose connective tissues called... | perimysium |
fasciculi are composed of single muscle cells called... | fibers |
muscle cells are called... | muscle fibers |
each fiber is surrounded by a connective tissue sheath called... | endomysium |
the cytoplasm of each fiber is filled with... | myofibrils |
myofibrils are... | a threadlike structure that extends from one end of the fiber to the other |
myofibrils consist of how many major kinds of protein fibers? | two |
what are the names for two protein fibers found in myofibrils? | actin myofilaments & myosin myofilaments |
which myofilament is thin and they resemble 2 minute strands of pearls twisted together? | actin myofilaments |
which myofilament is thick and resemble bundles of minute golf clubs? | myosin myofilaments |
actin and myosin form highly ordered units called... | sarcomeres |
what are the highly ordered units that joine4d end to end to form the myofibril? | sarcomeres |
what is the basic structural and functional unit if the muscle? | sarcomere |
each sarcomere extends from... | one Z Line (disc) to another Z Line (disc) |
each Z Line is an attachment site for... | actin |
the arrangement of actin and myosin give what kind of appearance? | banded appearance |
on each side of the Z Line is a light area called... | I Band |
what does the I Band consist of? | actin |
the A Band extends the length of... | myosin |
the A Band is the darker or lighter central region in each sarcomere? | darker |
in the center of each sarcomere is another light area called... | H Zone |
the H Zone consists of only myosin or actin | myosin |
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myosin myofilaments are anchored in the ______ of the sarcomere | center |
the outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged. the charge difference across the membrane is called the... | resting membrane potential |
when a muscle cell is stimulated the membrane characteristics change briefly. the brief reversal back of the charge is called... | action potential |
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motor neurons are nerve cells that carry action potentials to _______ muscle fibers | skeletal |
axons enter muscles and branch. each branch that connects to the muscle forms a... | neuromuscular |
near the center of the cell, each branch is called a... | synapse |
a single motor neuron and all skeletal muscle fibers it innervates are called a... | motor unit |
many motor units form what? | a single muscle |
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a neuromuscular junction is formed by an _____________ __________ ___________ resting in an indentation of the muscle cell membrane | enlarged nerve terminal |
the enlarged nerve terminal is the... | presynaptic terminal |
the space between the presynaptic terminal and the muscle cell is the... | synaptic cleft |
the membrane (or the muscle fiber) of the presynaptic terminal is the... | postsynaptic terminal |
each presynaptic terminal contains... | synaptic vesicles |
synaptic terminals secrete a neurotransmitter called... | acetylcholine |
acetylcholine diffuses across a synaptic cleft and binds to the postsynaptic terminal causing a change in the... | postsynaptic cell |
when an action potential reaches the nerve terminal, it causes the synaptic vesicles to release acetylcholine into the synaptic cleft by... | exocytosis |
the acetylcholine diffuses across the synaptic cleft and binds to receptor molecules in the muscle cell membrane. this action is called... | sarcolemma |
influx initiates an action potential in the muscle cell, which causes it to... | contract |
the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by an enzyme called... (HINT: really big word that ends with erase) | acetylcholinsterase |
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acetylcholine breakdown ensures that one action potential in the neuron yields only one action potential in the ______ muscle, and only one contraction of the ______ cell | skeletal; muscle |
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________ _________ occurs as actin and myosin myofilaments slide past one another causing the sarcomeres to shorten. | muscle contraction |
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when the sarcomeres shorten, it also causes the ________ to shorten | muscle |
the sliding of actin myofilaments past myosin myofilaments is called the... | sliding filament mechanism |
the H & I Bands shorten, but which bands do not change in length? | A Bands |
what term is a muscle 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... | threshold |
threshold is a phenomenon called the... | all-or-nothing repsonse |
the time between application of a stimulus to a motor neuron and the beginning of a contraction is the... | lag phase |
the time of contraction is the... | contraction phase |
relaxation phase is the time during... | which the muscle relaxes |
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if successive stimuli are given you get ________ twitches that occur so frequently the muscle doesn't have time to fully relax. | successive |
name the term where the muscle remains contracted without relaxing. | tetany |
the increase in number of motor units being activated is called... | recruitment |
what are two major energy requirements? | ATP & ADP |
what does ATP stand for? | adenosine triphosphate |
what does ADP stand for? | adenosine diphosphate |
where is ATP produced? | in the mitochondria |
ATP is needed for... | energy for muscle contraction |
is ATP short-lived or long-lived and unstable or stable? | short-lived; unstable |
is ATP or ADP more stable? | ADP |
is it necessary for muscle cells to constantly produce ATP? | yes |
creatine phosphate is... | another high-energy molecule that stored |
during periods of inactivity as excess ATP is produced in the muscle cell, the energy contained in the ATP is used to... | synthesize creatine phosphate |
during periods of activity, the energy stored in creatine phosphate can be accessed quickly and used to produce... | ATP |
what is anaerobic respiration? | without oxygen |
what is aerobic respiration? | with oxygen |
what results when ATP is used during muscle contraction faster than it can be produced? | muscle fatigue |
isometric is... | equal distance |
isotonic is... | equal tension |
muscle tone refers to... | constant tension |
fast-twitch fibers... | contract quickly and fatigue quickly |
slow-twitch fibers... | contract more slowly and are more resistant to fatigue |
muscles that work together to accomplish specific movements are called... | synergists |
muscles that work in opposition to one another are called... | antagonists |
what are some names that are descriptive about most muscles? | according to location, size, orientation of fibers, shape, origin, insertion, and function, etc. |