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74 Cards in this Set
- Front
- Back
What type of muscle?
❑ striated ❑ multinucleated |
skeletal muscle
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What type of muscle?
❑ striated ❑ single nucleus per cell |
cardiac muscle
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What type of muscle?
❑ striated ❑ voluntary control |
skeletal muscle
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What type of muscle?
❑ attached to bones, cartilage, or fascia |
skeletal muscle
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What type of muscle?
❑ striated ❑ involuntary control |
cardiac muscle
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What type of muscle?
❑ found only in the heart |
cardiac muscle
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What type of muscle?
❑ non-striated |
smooth muscle
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What type of muscle?
❑ found in the walls of blood vessels, the respiratory passages, and the hollow visceral organs other than the heart |
smooth muscle
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How are most skeletal muscles arranged in the body?
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in agonist/antagonist pairs
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List 4 functions of skeletal muscles.
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produce movement
maintain posture stabilize and strengthen joints generate heat (shivering) |
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______________ – attachment of a skeletal muscle that remains relatively fixed during muscular contraction
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muscle origin
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_______________ – attachment of a skeletal muscle that moves during muscular contraction
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muscle insertion
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Skeletal muscle cells are called __________.
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muscle fibers (or myofibers)
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Each muscle fiber in a skeletal muscle is surrounded by a sheath of reticular connective tissue proper called ____________.
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endomysium
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Muscle fibers are grouped into units called _____________.
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fascicles
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Muscle fibers are bundled together to form a fascicle by a surrounding connective tissue sheath called ______________.
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perimysium
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Fascicles are bundled together to form a skeletal muscle by a surrounding connective tissue sheath called _______________.
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epimysium
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______________ - the plasma membrane of a skeletal muscle cell
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sarcolemma
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______________ - the cytoplasm of a skeletal muscle cell
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sarcoplasm
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A complex organelle found only in skeletal and cardiac muscle that is composed of bundles of myofilaments
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myofibril
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The thin and thick filaments in a muscle cell are known as ____________.
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myofilaments
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In muscle cells, the thick filaments are composed of ___________.
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myosin
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In muscle cells, the thin filaments are composed of ___________.
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actin
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What forms the "cross-bridges" between the thick filaments and thin filaments in muscle cells?
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the myosin heads
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A rope-like protein arranged head to tail down the length of each actin filament in a muscle cell.
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tropomyosin
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What is tropomyosin doing in a resting muscle cell?
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It covers the myosin-binding sites on the thin filaments.
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Give 3 terms for the synapse between a motor neuron and a skeletal muscle fiber.
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neuromuscular synapse
neuromuscular junction motor end-plate |
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What neurotransmitter is used in the neuromuscular junction?
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acetylcholine
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What enzyme in the post-synaptic membrane of the motor end-plate destroys the neurotransmitter released from the motor neuron?
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acetylcholine esterase
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After the skeletal muscle action potential, what triggers the muscle contraction?
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an increase in the cytosolic Ca2+ concentration
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What feature of a striated muscle cell carries the muscle cell action potential deep into the cell interior?
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T-tubules
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What is the sarcoplasmic reticulum?
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a network of membrane-bound tubes inside muscle cells (esp. striated muscle cells) filled with Ca2+
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What term describes the sequence of events connecting the muscle action potential to the muscle contraction?
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excitation-contraction coupling
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In striated muscle, the muscle action potential causes the release of Ca2+ from intracellular stores. Where is the Ca2+ stored?
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in the sarcoplasmic reticulum
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In striated muscle, the muscle action potential causes the release of Ca2+ from the sarcoplasmic reticulum. What happens next?
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The Ca2+ binds to troponin, which then pulls the tropomyosin out of the way so that myosin can grab hold of the thin filaments and pull.
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An increase in the cytosolic Ca2+ concentration triggers muscle cell contraction. What happens to the Ca2+ that causes the muscle cell to relax?
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The Ca2+ is pumped back into the sarcoplasmic reticulum (striated muscle) or outside the cell (smooth muscle).
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A Ca2+ pump is also called a __________.
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Ca2+ ATPase
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What is the latent period of a skeletal muscle twitch?
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the time between the end of the skeletal muscle action potential and the beginning of contraction
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Define motor unit.
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a single motor neuron and all the skeletal muscle fibers it innervates.
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In what order are motor units recruited?
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in order of increasing size
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Define motor neuron pool.
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all of the motor neurons that innervate a given skeletal muscle
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A skeletal muscle contraction for which the force applied by the muscle is not sufficient to move the load. Consequently, the muscle does not shorten.
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isometric contraction
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A skeletal muscle contraction for which the muscle tension remains relatively constant.
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isotonic contraction
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An isotonic contraction during which the contracting skeletal muscle shortens.
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concentric contraction
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An isotonic contraction during which the contracting skeletal muscle lengthens.
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eccentric contraction
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A muscle cell which is being stimulated to hold a contraction very quickly begins to run low on ATP. How will the muscle cell quickly replenish its ATP supply?
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by transferring a phosphate from creatine-phosphate to ADP
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1 molecule glucose is catabolized to 2 pyruvate molecules in a process referred to as _____________.
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anaerobic glycolysis
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Does glycolysis require oxygen?
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NO
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Where in the cell does glycolysis occur?
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in the cytosol
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In glycoltic muscle, what happens to the pyruvate formed in glycolysis?
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It is converted to lactic acid, which is then transported out of the cell.
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What energy substrate does glycolytic muscle primarily use?
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glucose
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In oxidative muscle, what happens to the pyruvate produced by glycolysis?
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It is oxidized in the mitochondria for energy.
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How are fatty acids metabolized for energy?
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by oxidation in the mitochondria
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____________- the amount of extra oxygen required by muscle tissue during recovery from vigorous exercise
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oxygen debt
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What is ATP used for in a muscle contraction?
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1. the myosin ATPase activity for myosin to pull on the thin filaments
2. the Ca2+ pump to pump the Ca2+ back into the sarcoplasmic reticulum (striated muscle) or back out of the cell (smooth muscle) 3. the Na+/K+ pump to return the plasma membrane back to the resting membrane potential |
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Give 3 names for skeletal muscle fibers that primarily use oxidation for energy.
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slow oxidative (SO) fibers
type I fibers red muscle fibers |
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What muscle fibers are the least fatigue-resistant??
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fast glycolytic (FG) fibers (white muscle fibers)
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What muscle fibers are the most fatigue-resistant?
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slow oxidative fibers (red muscle fibers)
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What type of muscle fiber?
❑ low glycogen content ❑ high mitochondrial content ❑ high myoglobin content ❑ high capillary density |
slow oxidative fibers (red muscle fibers)
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What type of muscle fiber?
❑ high glycogen content ❑ low mitochondrial content ❑ low myoglobin content ❑ low capillary density |
fast glycolytic (FG) fibers (white muscle fibers)
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Give 3 names for skeletal muscle fibers that primarily use glycolysis for energy.
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fast glycolytic (FG) fibers
type IIb fibers white muscle fibers |
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What skeletal muscle fiber type is best for short bursts of intense activity?
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fast glycolytic (FG) fibers
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Give another term for cardiac muscle cells.
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cardiomyocytes
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Cardiac or smooth muscles cells specialized to produce
rhythmic action potentials |
pacemaker cells
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In cardiac muscle, an action potential originates from pacemaker cells and spreads throughout the muscle. How does the action potential spread from one cardiomyocyte to the next?
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through gap junctions
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What is the major difference in excitation-contraction coupling between skeletal and cardiac muscle?
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Ca2+-induced Ca2+ release occurs in cardiac muscle.
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Explain Ca2+-induced Ca2+ release that occurs in stimulated cardiomyocytes.
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There is a voltage-gated Ca2+ channel in the t-tubules of cardiomyocytes. An action potential traveling down the t-tubules opens the voltage-gated Ca2+ channels, allowing Ca2+ from outside the cell to come into the cell. This Ca2+ then binds to and opens a ligand-gated Ca2+ channel in the sarcoplasmic reticulum.
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Where does most of the Ca2+ for smooth muscle contraction come from?
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from outside the cell (i.e. from the interstitial fluid)
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What type of smooth muscle?
❑ Cells are coupled by numerous gap junctions. ❑ contains pacemaker cells ❑ degree of contraction can be modulated by autonomic stimulation |
single-unit smooth muscle
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What type of smooth muscle?
❑ cells contract independently ❑ extensively innervated ❑ innervation necessary to induce contraction |
multi-unit smooth muscle
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Autonomic nerve fibers release neurotransmitter onto smooth muscle cells from...
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varicosities (swellings) in the nerve axons
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When a smooth muscle cell is excited, Ca2+ enters the cell and binds to ___________.
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calmodulin
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How is tropomyosin moved off of the myosin-binding sites of actin in smooth muscle?
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In smooth muscle, tropomyosin is held in the way by a protein called caldesomon. Ca2+-calmodulin binds to caldesmon and pulls it off the tropomyosin.
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After tropomyosin moves out of the way, there is still one more step before the mysoin can begin pulling on the thin filaments in smooth muscle. What is this step?
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Myosin light-chain kinase (activated by Ca2+-calmodulin) must phosphorylate the regulatory myosin light chains.
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