Muscle tissue
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Created by:
csaluki762 on March 24, 2010
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63 terms
Terms | Definitions |
|---|---|
 myology | the scientific study of muscles |
| sphincter | ringlike band of smooth muscle that prevents outflow of the contents of a hollow organ |
| thermogenesis | heat production due to muscle contraction that helps maintain normal body temperature |
| excitability | the ability of muscle fibers to receive and respond to stimuli |
| contractility | the ability of cells or parts of cells to actively generate force to undergo shortening for movements |
| extensibility | the ability of muscle tissue to stretch when it is pulled |
| elasticity | the ability of tissue to return to its original shape after contraction or extension |
| muscle fibers | another name for muscles cells, due to their elongated shapes |
| fascia | a dense sheet or broad band of dense irregular connective tissue that lines the body wall and limbs and supports and surrounds muscles and other body organs; holds muscles with similar functions together |
| epimysium | the outermost layer of connective tissue that encircles the entire muscle |
| perimysium | connective tissue layer that surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles |
| fascicle | a small bundle or cluster of muscle fibers |
| endomysium | a connective tissue layer that separates individual muscle fibers from one another |
| tendon | a cord of dense regular connective tissue composed of parallel bundles of collagen fibers that attach a muscle to a periosteum of a bone |
| aponeurosis | a tendon that resembles a broad, flat layer |
| hypertrophy | growth resulting in an enlargement of existing muscle fibers |
| hyperplasia | growth due to an increase in the number of muscle fibers |
| fibrosis | the replacement of muscle tissue by scar tissue |
| sarcolemma | the plasma membrane of a muscle cell |
| transverse (T) tubules | tiny, cylindrical invaginations of the sarcolemma of striated muscle fibers that conduct muscle action potentials toward the center of each muscle fiber |
| sarcoplasm | the cytoplasm of a muscle fiber |
| myoglobin | red-colored, iron-containing muscle protein that binds oxygen molecules that diffuse into the muscle fiber sarcoplasm from interstitial fluid |
| myofibrils | threadlike structures that extend longitudinally through a muscle fiber consisting mainly of thick filaments and thin filaments |
| sarcoplasmic reticulum (SR) | fluid-filled system of membranous sacs that encircle each myofibril; stores and releases calcium ions |
| muscular atrophy | a wasting away of muscles because of progressive loss of myofibrils due to disuse or denervation |
| filaments | the thin and thick proteins within myofibrils that are directly involved in the contractile process |
| sarcomere | the basic functional contractile unit of a myofibril |
| Z discs | narrow, plate-shaped regions of dense protein that separate one sarcomere from the next |
| A band | the darker middle part of the sarcomere which extends the entire length of the thick filaments |
| M line | supporting proteins that hold the thick filaments together in the middle of the sarcomere |
| myosin | the contractile protein that makes up the thick filaments of muscle fibers |
| actin | a contractile protein that is part thin filaments of muscle fibers |
| tropomyosin | one of two regulatory proteins that is part of the thin filament; covers the myosin-binding sites on actin |
| troponin | one of two regulatory proteins that is part of the thin filament; binds to calciumm ions and undergoes a shape change that moves tropomyosin away from the myosin-binding sites on actin |
| sliding filament model | the model that describes how skeletal muscle shortens during contraction due to the thin filaments sliding past the thick filaments |
| crossbridges | form when the myosin heads attach to actin during contraction |
| somatic motor neurons | the nerve cells that stimulate skeletal muscle fibers to contract |
| neuromuscular junction (NMJ) | the synapse between a somatic motor neuron and a skeletal muscle fiber |
| synapse | a region where communication occurs between two neurons, or between a neuron and a target cell |
| synaptic cleft | a small gap at the synapse that separates the two cells |
| neurotransmitter | chemicals that allow the first cell at a synapse to communicate with the second cell |
| synaptic vesicles | hundreds of membrane-enclosed sacs that are suspended in the cytosol within each synaptic end bulb |
| acetylcholine (ACh) | the neurotransmitter stored in synaptic vesicles that is released at the neuromuscular junction |
| motor end plate | the region of the muscle fiber sarcolemma opposite the synaptic end bulbs |
| creatine phosphate | an energy-rich molecule found only in muscle fibers that is synthesized when there is excess ATP |
| anaerobic cellular respiration | a series of ATP-producing reactions that do not require oxygen |
| aerobic cellular respiration | a series of oxygen-requiring reactions that produce ATP in mitochondria |
| muscle fatigue | the inability of a muscle to maintain force of contraction after prolonged activity |
| oxygen debt (recovery oxygen uptake) | refers to the added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise |
| motor unit | a somatic motor neuron plus all the skeletal muscle fibers it stimulates |
| myogram | a visual record of a muscle contraction |
| latent period | the brief delay that occurs between application of the stimulus and the beginning of contraction; the muscle action potential sweeps over the sarcolemma and calcium ions are released from the sarcoplasmic reticulum |
| contraction period | during this time, calcium ions bind to troponin, myosin-binding sites on actin are exposed, and crossbridges form |
| relaxation period | during this time, calcium ions are actively transported back into the sarcoplasmic reticulum, myosin-binding sites are covered by tropomyosin, myosin heads detach from actin, and tension in the muscle fiber decreases |
| refractory period | the time when a muscle fiber receives enough stimulation to contract that it temporarily loses its excitability and cannot respond for a time |
| muscle tone | a small amount of tautness or tension in the muscle due to weak, involuntary contractions of its motor units |
| isotonic contraction | the tension (force of contraction) developed by the muscle remains almost constant while the muscle changes its length; used for body movements and for moving objects |
| isometric contraction | occurs when the tension generated is not enough to exceed the resistance of the object to be moved, and the muscle does not change its length; holding a book steady using an outstretched arm |
| slow oxidative (SO) fibers | muscle fibers that are the smallest in diameter, the least powerful, appearing dark red due to large amounts of myoglobin and many blood capillaries; fatigue-resistant fibers that are adapted for maintaining posture and for aerobic, endurance-type activities like running a marathon |
| fast oxidative-glycolytic (FOG) fibers | muscle fibers that are intermediate in diameter, appearing dark red due to large amounts of myoglobin and many blood capillaries; used in walking and sprinting |
| fast glycolytic (FG) fibers | muscle fibers that are the largest in diameter and contain the most myofibrils; able to generate the most powerful contractions; low myoglobin content and few blood capillaries; adapted for intense anaerobic movements of short duration such as weight lifting |
| cardiac muscle fibers | the contractile cells of the heart |
| smooth muscle tone | a state of continued partial contraction that can sustain long-term tone in the GI tract and in the walls of blood vessels to maintain blood pressure |
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