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ALS (amyotrophic lateral sclerosis) is a disease that destroys nerve cells that control skeletal muscle activity. Without neural stimulation, skeletal muscles eventually waste away and mobility is impossible. In other words, skeletal muscles __________. |
Become atrophied |
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Which of these characteristics applies only to cardiac muscle tissue? |
Intercalated discs |
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Which of these increases as muscles age? |
Amount of connective tissue in a muscle |
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What can older individuals do to increase muscle strength? |
Regularly use hand weights and practice leg lifts |
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What mineral is released within muscle cells to trigger contraction? |
Calcium |
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What term refers to a smooth, sustained contraction? |
Complete tetanus |
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Which of these muscles is located in the neck? |
Sternocleidomastoid |
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Which of these muscles extends the knee? |
Rectus femoris |
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Which connective tissue bundles muscle fibers into fascicles? |
Perimysium |
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Which of these muscles is named for the arrangement of its fascicles? |
External oblique |
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What is the function of creatine phosphate? |
Directly regenerates ATP from ADP within a muscle cell |
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There are three types of muscle tissue. Which of the following is classified as part of the muscular system? |
All skeletal muscles |
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What term describes the rotation of a bone around its longitudinal axis? |
Rotation |
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What term refers to a muscle that aids another muscle by producing the same the movement or reducing undesirable movements? |
Synergist |
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What metabolic waste accumulates in muscle with excessive exertion? |
Lactic acid |
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What initiates an action potential on a muscle cell? |
Acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction |
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Which neurotransmitter is released by motor neurons at the neuromuscular junction? |
Acetylcholine |
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A muscle inserts on which of the following? |
The bone that moves when the muscle contracts |
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Which of these muscles moves the upper limb? |
Latissimus dorsi |
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What happens to a muscle when the nerve supplying that muscle is cut? |
Muscle paralysis and atrophy occur. |
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Which movement is associated with the hand but actually occurs in the forearm? |
Supination |
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he cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge? |
A myosin head bound to actin |
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What structure is the functional unit of contraction in a skeletal muscle fiber? |
The sarcomere |
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Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber? |
Calcium ions are stored in the sarcoplasmic reticulum |
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When does cross bridge cycling end? |
Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin. |
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