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Chapter 8 Muscles
anatomy
| Term | Definition |
|---|---|
| myology | the study of muscle tissue |
| functions of muscles | movement, maintaining posture, stabilizing joints, producing heat (thermogenesis), protect organs |
| skeletal muscle | longest fibers of all muscles and have striations, also called voluntary muscle, contracts rapidly, tires easily, and is very powerful |
| cardiac muscle | type of muscle found only in the heart, is striated and involuntary |
| smooth muscle | found in walls of hollow organs, not striated and involuntary, elongated cells; also called visceral muscles |
| excitability | ability to respond to a stimulus by producing electrical signals impulses within the body |
| contractility | ability to shorten and thicken (contract), therefore generating force to do work |
| extensibility | ability to stretch without damage to the tissue |
| elasticity | the ability to return to its original shape after stretching or contracting |
| skeletal muscle fiber | muscle cell or myofiber |
| sarcolemmma | cell membrane of muscle cell |
| sarcoplasm | cytoplasm of muscle cell |
| myofiliments | many myofibrils |
| actin and myosin | myofibrils consist of what |
| sarcomeres | contractile units of a muscle |
| nerve and blood supply, connective tissue sheets, attachments | 3 major features of skeletal muscle |
| fascia | band or sheet of connective tissue found beneath the skin; attaches, stabilizes, encloses, and separates muscles and other internal organs; primarily made of collagen, covers the entire muscle |
| epimysium | surrounds the whole muscle |
| perimysium | surrounds fascicles (bundle of muscle fibers) within a muscle |
| endomysium | surrounds muscle fibers (cells) withing a fascicle |
| tendon | flexible cord of strong fibrous collagen tissue attaching a muscle to a bone |
| aponeuroses | sheet of pearly while fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment |
| I band | light band composed of thin actin filaments |
| A band | dark band, composed of thick myosin filaments with portions overlapped with thin actin filaments |
| H zone | center of A band, composed of thick myosin filaments |
| Z line | anchors filaments in place; sarcomere boundary, center of I band |
| M line | anchors thick filaments, center of A band |
| presynaptic neuron | motor neuron that conducts the impulse to the skeletal muscle; located before the synapse |
| postsynaptic cell | receives the neurotransmitter after it has crossed the synapse and may experience an action potential if the neurotransmitter is strong enough; is located after the snyapse |
| neuromuscular junction | site of the chemical synapse between a motor neuron and a muscle fiber; allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction |
| synaptic cleft | gap between the axon terminal of the presynaptic neuron and the membrane of the postsynaptic cell |
| synaptic end bulb | where ACh (a neurotransmitter) is stored |
| synaptic vesicles | membrane-enclosed sacs found within the synaptic end bulb |
| neurotransmitters | chemical messengers that transmit a message from a nerve cell across the synapse to a target cell (another nerve cell, muscle cell, or gland cell) |
| motor end plate | specialized region on the muscle fiber sarcolemma that receives the neurotransmitter; also known as the postsynaptic membrane |
| sliding filament theory | describes the process used by muscles to contract; a cycle of repetitive events that causes actin and myosin myofilaments to slide over each other, contracting the sarcomere and generating tension in the muscle |
| aerobic respiration | during rest or moderate exercise, respiratory and cardiovascular systems supply enough oxygen to support this |
| anaerobic (lactic acid) threshold | occurs during strenuous muscle activity, when the respiratory and cardiovascular systems can't supply the necessary oxygen; lactic acid is produced and causes muscle soreness |
| cellular respiration | living cells break down glucose molecules, release energy, and form molecules of ATP |
| muscle fatigue | inability to contract muscle |
| muscle cramp | sustained, involuntary muscle contraction; may be caused by changes in electrolyte concentration in extracellular fluids in the area |
| twitch | when stimulated by a single action potential a muscle contracts and the relaxes |
| summation | process by which the force of individual muscle fiber twitches combine; produces sustained contractions |
| tetanus | sustained contractions accompanied by peak muscular tension and no relaxation observed; can be caused by bacterial toxins |
| isometric contraction | a muscular contraction in which the length of the muscle does not change but tension increases |
| isotonic contraction | a muscular contraction in which the length of the muscle changes |
| eccentric | an isotonic contraction where the muscle lengthens |
| concentric | an isotonic contraction where the muscle shortens |
| insertion | attach to movable bone, usually distal to the body |
| origin | attach to immovable or less movable bone, usually proximal to the body |
| belly | pat of the muscle between the origin and insertion |
| direct (fleshy) | epimysium fused to periosteum (outer membrane) of bone or perichondrium of cartilage |
| indirect | connective tissue extends beyond muscle as rope-like tendon or sheet-like aponeurosis |
| orgin | less movable end of skeletal muscle |
| insertion | more movable end of skeletal muscle |
| agonist | muscle that causes an action |
| prime mover | agonist primarily responsible for movement |
| synergists | muscles that assist against prime mover; they work together |
| antagonist | muscles whose contraction causes movement in the opposite direction of the prime mover |
| muscular atrophy | the decrease in size and wasting of muscle tissue |
| hypertrophy | an increase and growth of muscle cells |
Created by:
lydia werling
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