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29 Cards in this Set
- Front
- Back
3 types of muscles, their locations, and whether or not they are voluntary/involuntary
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skeletal-skeleton-striated-no cell junctions-voluntary; cardiac-heart-striated-cell junctions (intercalated discs)-involuntary; smooth-stomach, digestive organs, bladder, blood vessels, uterus-involuntary
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three functions of muscles
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produce movement by interacting with skeleton, resist movement by generating a force, generate heat to maintain body temperature
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what happens when muscle cell contracts and relaxes
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contracts- shortens, relaxes - returns to original length
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muscle groups that work together to create the same movement
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synergistic muscles
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muscle groups that oppose each other to produce opposite movements
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antagonistic muscles
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In muscle contraction, the point of attachment of muscle to bone that does not move is the ____. It is usually ___ to the body trunk. The point of attach. to the movable bone in a contraction is its ___. It is usually ___ from the body trunk.
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origin, proximinal, insertion, farther
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When a muscle contracts, its __ is pulled toward its __.
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insertion, origin
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explain how biceps and triceps works
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biceps contracts, insertion of biceps pulls on radius, which raises or flexes forearm; triceps contracts, the insertion of the triceps pulls on the ulna, which lowers or extends forearm
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the act of bending
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contracting
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a group of individual muscle cells or ____, which all have the same ___ and ___ and function
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fibers, origin, insertion
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groups of muscle cells/fibers arranged together in a bundle; surrounded by a fibrous conn tissue sheath called __
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fasicle; fascia
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myofibril striation due to ___ and ___
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actin and myosin
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the smallest contractile unit of a muscle myofibril
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sarcomere
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muscle contraction is caused by shortening of sarcomeres, which shorten by a _________, in which actin filaments slide past myosin filaments
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sliding filament mechanism
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skeletal muscle cells are stimulated by ____, which releases ____, which initiates the _______, which causes the shortening of sarcomeres and contraction of the muscle.
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neurons, calcium, sarcomeres
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the area where a motor neuron comes in close contact with a muscle cell
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neuromuscular junction
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Read this (muscle contraction).
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Electrical impulses from the brain and spinal cord travel through a motor neuron to a skeletal muscle. When an electrical impulse reaches the neuromuscular junction, a neurotransmitter called acetylcholine is released from the neuron. Bind of this neurotransmitter to the muscle cell membrane causes the membrane to generate an electrical impulse. Extensons of the membrane called T tubules carry this impulse deep into the interior of the muscle cell and the sarcoplasmic reticulum. The impulse stimulates the sarcoplasmic reticulum to release stored calcium ions, which then bind with special proteins on myosin and allow cross-bridges to form between the myosin heads and actin filaments. The myosin heads bend and physically pull the actin filaments, which causes the sarcomere to shorten.
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Read this (muscle relaxation).
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When nerve stimulation stops, electrical impulses in the muscle stop. The sarcoplasmic reticulum stops releasing calcium and any calcium that had already been released is transported back into the sarcoplasmic ret. by active transport. As the calcium concentration decreases, the cross bridges btwn actin and myosin dissemble, the sarcomere stretched back to original length and the muscle cell relaxes.
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energy for muscle activity
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ATP
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3 functions of ATP in muscle contract/relax
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binds myosin heads to actin to form cross bridges and to detach myosin heads from actin in sliding filament mechanism; transports calcium back into the sarcoplasmic ret at the end of contraction;detaches myosin heads from actin so that relaxation can occur
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What causes rigor mortis?
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shortly after death, calcium leaks out of sarcoplasmic ret, causes muscle contraction, uses up ATP, myosin heads cannot detach from actin, muscles remain contracted until they degenerate
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weight lifters muscles rely on stored ATP first, and then ___ and ___ stores
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creatine phosphate, glycogen
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slow twitch muscle fibers are for activities that require
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endurance
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fast twitch muscle fibers are for activities that require
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rapid contraction
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exercise increases aerobic capacity, muscle mass, and muscle strength, but not
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the number of muscle cells
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muscle weakness caused by immune system destruction of acetylcholine receptors on muscle cell membranes
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myasthenia gravis
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calcium leakage and destruction of muscle cells caused by lack of dystrophin muscle protein
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muscular dystrophy
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overstimulation of nerves and sustained muscle contractions produced by bacterial toxins from a puncture wound
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tetanus
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painful muscle contractions caused by dehydration and ion imbalances, esp. potassium
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muscle cramps
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