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135 Cards in this Set
- Front
- Back
Location
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Skeletal muscle - attached to skeleton
Smooth muscle - walls of intestines, blood vessels, etc. Cardiac muscle - walls of heart |
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Control
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Skeletal muscle - voluntary
Smooth muscle - involuntary Cardiac muscle - involuntary |
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Shape of fibers
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Skeletal muscle - elongated, cylindrical, blunt ends
Smooth muscle - elongated, spindle shaped, pointed ends Cardiac muscle - elongated, cylindrical fibers that brance |
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Striations
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Skeletal muscle - present
Smooth muscle - absent Cardiac muscle - present |
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#nuclei per fiber
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Skeletal muscle - many
Smooth muscle - one Cardiac muscle - one or two |
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Position of nuclei in cell
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Skeletal muscle - peripheral
Smooth muscle - central Cardiac muscle - central |
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Speed of contraction
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Skeletal muscle - most rapid
Smooth muscle - slowest Cardiac muscle - intermediate |
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Ability to remain contracted
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Skeletal muscle - least
Smooth muscle - greatest Cardiac muscle - intermediate |
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Muscle fiber/muscle cell
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Structural unit of the muscle tissue
Has elongated shape |
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Smooth (unstriated) muscle
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mass of individual spindle-shaped contractile cells
Walls of digestive tract and uterus, linings of blood vessels, certain ducts |
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Cardiac muscle
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more organization ofthe contracting proteins than in smooth muscle cells
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Striated muscle/skeletal muscle
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each muscle cell is a fused set of dozens or hundreds of cells
very long, also called muscle fibers Ability to exert force in one direction |
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Muscle cells contraction
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contract by active mechanism - when stimulation is provided
relax by passive mechanism |
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antagonistic muscles
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muscles that move body parts in different directions
i.e. flexor and extensor muscles |
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Endomysium
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connective tissue that wraps individual muscle fibers
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Perimysium
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wraps bundles of muscle fibers
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fasicles
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bundles of muscle fibers
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epimysium and fascia
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enclose the entire muscle
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Superficial fascia
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contains much fat in obese individuals
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Gaster
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portion of the muscle with fibers
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voluntary control of muscle
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contracts only when stimulated by neurons that deliver nerve impulses to it
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myofibrils
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4 - 20 rod-like filaments in each fiber
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Sacroplasm/cytoplasm
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bathes the myofibrils
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Mitochondria
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scattered throughout the sacroplasm
provide ATP as an energy source for the contraction of myofibrils |
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sacromeres
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smaller units along the length of myofibrils
each about 2 micrometers in length Functional unit of skeletal muscle Gives muscle striated pattern |
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Thin filaments
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one of 2 types of myofilaments which compose sarcomere
Run parallel to one another made of protein actin |
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Thick filaments
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one of 2 types of myofilaments which compose sarcomere
Made of protein myosin |
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Z line
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The point where actin filaments from adjacent sarcomeres interweave in a line
Bisects relatively clear broad strip called the I band |
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I band
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Broad stripe on sarcomere bisected by Z line
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A band
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Dense stripe in the center of the sarcomere formed by overlapping myosin filaments
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H Zone
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Bisects A band
contains myosin filaments but no actin filaments |
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Striated muscle
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formed by repeating A and I bands in the myofibrils
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Sliding filament model
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myosin heads act as crossbridges between actin and myosin filaments
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Power stroke
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pulls actin filaments inward toward the H zone
sliding shortens the sarcomeres muscle shortens and contracts |
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Adenosine Triphosphate (ATP)
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broken down by enzymes into ADP
bginds to enzyme on myosin head ATP molecule is cleaved, ADP and phosphate remain bound to the head. |
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Red muscle/oxydative muscle (slow)
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large quantity of reddish molecul myoglobin, where oxygen is stored
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White muscle / glycolytic muscle (fast muscle)
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plentiful glycogen
little or no myoglobin, stores little oxygen. ATP is used up quickly and cannot be replaced rapidly. Becomes fatigued with build up of lactic acid. |
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Tropomyosin
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molecules of a protein in the grooves of the actin helix
When muscle is at rest, prevents myosin heads from binding to actin by masking the site where binding would ordinarily occur |
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Troponin
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protein found at regular intervals along the actin filament
Binds to both tropomyosin molecules and actin molecules Binds to calcium ions |
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Acetylcholine
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neurotransmitter released when nerve impulses reach the muscle fiber at the neuromuscular junction
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Neurmuscular junction
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consists of a single muscle fiber and the terminal end of a single nerve cell.
Nerve and muscle cells are close, but don't touch remain separated by synapse |
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Synapse
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space between nerve and muscle cells
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Sodium ions
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in resting cells, concentration is kept low by active transport
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Sarcolemma of muscle fiber
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plasma membrane of muscle fiber where sodium ions rush in when acetylcholine binds receptors
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Calcium ions
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concentration in the cytoplasm of resting muscle is low because it is pumped out of the cell or into the cells specialized endoplasmic reticulum or sarcoplasmic reticulum
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Transverse tubules / T tubules
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system of infoldings of teh plasma membrane or sacrolemma
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All-or-nothing response
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Fiber contracts only after an impulse exceeds a certain threshold and spreads through the cell.
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Graded response to stimulus
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Entire muscles do not have all or nothing response
Response is graded depending on number of contracting fibers in a muscle. |
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Motor unit
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Muscle fibers and the neuron that stimulates them
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Twitch
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contraction of amuscle fiber
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Sumation
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increasing number of twitches occurring in a muscle due to continued stimulation
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Tetanus
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a state of sustained maximum contraction
i.e. making a fist |
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Tonus
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muscle tone - a condition in which a muscle is kept partially contracted over a long period of time
One set of fibers, then another set is briefly stimulated so some of the muscle is always contracted |
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Normal posture
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achieved by tonus
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Creatine phosphate
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one of the sources for regenerating ATP
contains high energy phosphate bonds storage depot for cellular energy |
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Anerobic reactions of glycosis
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glucose molecules are converted through multiple steps into pyruvic acid molecules
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Lactic acid
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if cell's oxygen is depleated pyruvic acid is converted into lactic acid
causes pH changes and muscle fibers respond poorly to stimulation |
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Oxygen debt
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occurs as lactic acid accumulates. Oxygen must be supplied to prevent further buildup of lactic acid
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Smooth muscle
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slender, elongated, spindle shaped cells without striations and with a single nucleus
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Gap junctions
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link some smooth muscle cells together
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Visceral muscle
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another name for smooth muscle
found in visceral organs no sarcomeres Thin and thick filaments are collected into bundles |
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Dense bodies
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permit attachment of thin filaments in smooth muscle
Counterparts to Z lines in skeletal muscles |
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Single unit smooth muscle
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visceral muscle whose fibers contract together as a rhythmic unit, and are coupled by one another by gap junctions
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Multi unit smooth muscle
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Lines the airways to the lungs and the large arteries and the erector pili muscles of the hair follicles.
Fibers work independently of one another - gap junctions rare |
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Intercalated discs
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Binds ends of cardiac muscle together
Many gap junctions- electrical current flows easily. |
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The type of muscle found in the walls of the digestive tract is the
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smooth muscle
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Heart muscle is also known as
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cardiac muscle
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The most abundant type of muscle in the human body is a striated muscle, also known as
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skeletal muscle
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Muscles that work against each other are said to be
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antagonistic muscles
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The submicroscopic filaments of a muscle cell are known as
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myofibrils
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The functional unit of muscle activity is correctly known as the
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sarcomere
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The thick filaments in the central portion of the sarcomere are composed of the protein
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myosin
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The thin filaments of a sarcomere are composed of the protein
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actin
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The thin filaments of a sarcomere in a skeletal muscle fiber are anchored to the
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Z line
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The theory that explains the contraction of muscle fibers is called the
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sliding filament theory
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During muscle contractions, the thick filaments pull on the thin filaments attached to the Z lines and shorten the
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sarcomere
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The primary source of energy for muscle contraction is
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ATP
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Red muscle has much oxygen stored in a red-pigmented molecule called
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myoglobin
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The continual contractions of muscle fibers require a supply of the energy molecule
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ATP
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White muscle is so named because it has little or no
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myoglobin
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White muscle is not able to store much
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oxygen
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White muscle uses stored glycogen for energy, and is sometimes called
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glycolytic muscle
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When a muscle is at rest, myosin heads are prevented from binding to actin by a protein called
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tropomyosin
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Muscles are triggered to contract following release of the neurotransmitter
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acetylcholine
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The first ion utilized during muscle contraction is
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sodium
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Calcium ions are stored in muscle cells within infoldings of the plasma membrane called
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transverse tubules
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Following their release, calcium ions trigger muscle contractions by binding to the molecule
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troponin
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The binding of calcium to troponin causes a shift in the molecule
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tropomyosin
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The shift of position of tropomyosin unmasks the sites on actin filaments that bind to the heads of
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myosin
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Muscle contractions come to an end when tropomysin covers the myosin-binding sites on
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actin
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Energy is used during muscle contraction to move calcium ions into the sarcoplasmic reticulum and the
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T tubules
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The state of continual muscle contraction following death is called
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rigor mortis
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Muscle contracts after its threshold has been reached, and the response is called the
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all-or-nothing response
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The variable response displayed by a muscle fiber is known as the
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graded response
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The number of muscle fibers contracting in a muscle depends on the stimulation from
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nerve impulses
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The contraction of a muscle fiber is known as a
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twitch
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All the muscle fibers stimulated by one motor neuron constitute a
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motor unit
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The increasing number of twitches occurring with continued muscle
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summation
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A state of sustained maximum contraction of a muscle is a phenomenon called
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tetanus
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The condition in whih a muscle is kept partially contracted over a long period of time is called
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tonus
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When ATP is broken down in muscle cells, the two end products are phosphate groups and
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ADP
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One source for regernerating ATP is the high-energy molecule
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creatine phosphate
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In order for the most energy to be released from carbohydrate molecules in muscle cell metabolism, an essential gas is
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oxygen
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When muscle is oxygen-depleted, the energy for muscle contraction is derived from an anaerobic process called
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glycolysis
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Extreme muscle fatigue is generally due to teh buildup of an acid called
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lactic acid
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Energy is used during muscle contraction to move calcium ions into the sarcoplasmic reticulum and the
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T tubules
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The state of continual muscle contraction following death is called
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rigor mortis
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Muscle contracts after its threshold has been reached, and the response is called the
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all-or-nothing response
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The variable response displayed by a muscle fiber is known as the
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graded response
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The number of muscle fibers contracting in a muscle depends on the stimulation from
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nerve impulses
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The contraction of a muscle fiber is known as a
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twitch
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All the muscle fibers stimulated by one motor neuron constitute a
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motor unit
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The increasing number of twitches occurring with continued muscle
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summation
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A state of sustained maximum contraction of a muscle is a phenomenon called
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tetanus
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The condition in which a muscle is kept partially contracted over a long period of time is called
|
tonus
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When ATP is broken down in muscle cells, the two end products are phosphate groups and
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ADP
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One source for regenerating ATP is the high-energy molecule
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creatine phosphate
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In order for the most energy to be released from carbohydrate molecules in muscle cell metabolism, an essential gas is
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oxygen
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When muscle is oxygen-depleted, the energy for muscle contraction is derived from an anaerobic process called
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glycolysis
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Extreme muscle fatigue is generally due to the buildup of an acid called
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lactic acid
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Following strenuous activity, a person breathes deeply to repay an
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oxygen debt
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Much of the lactic acid produced during strenuous muscle activity is carried from the muscle cells for metabolism by the
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liver
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Where contractions of the skeletal muscles are fast, the contractions of smooth muscles are generally
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slow
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Smooth muscle is so named because it contains no
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stiations
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The muscle cells between some smooth muscles are linked together by junctions known as
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gap junctions
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Where skeletal muscles are voluntary muscles, the smooth muscles are
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involuntary
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Because smooth muscle is found in the internal organs, it is sometimes called
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visceral muscle
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Cardiac muscle is striated, and it is liberally supplied by energy yielding organelles called
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mitochondria
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The ends of cardiac muscle cells are connected to one another by gap junctions in
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intercalated disks
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Cardiac muscle is similar to smooth muscle because it is not under
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voluntary control
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Smooth muscle may be found in the
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digestive tract
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The two proteins of the myofibrils are
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actin and myosin
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The Z line, I band, A band, and H zone are all anatomical parts of the
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sarcomere
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For the successful completion of a muscle contraction, the sarcoplasmic reticulum
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ATP,l which breaks down and releases energy
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During muscle contraction, calcium ions bind to sites
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on troponin molecules
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