Human Biology

Front 1

tendon

Back 1

a band of connective tissue that connects muscle to bone.

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origin

Back 2

in reference to a muscle, the end of the muscle that is attached to the bone that remains relatively stationary during a movement.

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insertion

Back 3

the end of the muscle that is attached to the bone that moves when the muscle contracts.

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antagonistic pair

Back 4

muscles arranged in pairs so that the actions of themembers of the pair are opposite to one another. this arrangement is characteristic of most skeletal muscles.

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striated muscle

Back 5

one of three types of muscle in the body, it's cells are cylindrical, have many nuclei, and have stripes (striations). it provides for conscious, voluntary control over contraction. it attaches to bones and forms the muscles of the body. is is also called skeletal muscle.

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myofibiril

Back 6

a rodlike bundle of contractile proteins (myofilaments) found in skeletal and cardiac muscle cells essential to muscle contractions.

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myofilament

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a contractile protein within muscle cells. there are two types: myosin (thick) filaments and actin (thin) filaments.

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myosin filament

Back 8

the thick filaments in muscle cells composed of the protein myosin and essential to muscle contraction. it is shaped like a golf club with two heads.

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actin filament

Back 9

the thin filaments in muscle cells composed primarily of the protein actin and essential to muscle contraction. inaddition to this, thin filaments contain two proteins important in the regulation of muscle contraction; tropomyosin and troponin.

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sarcomere

Back 10

the smallest contractile unit of a striated or cardiac muscle cell.

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sliding filament model

Back 11

a model of the mechanism of muscle contraction in which the myofilaments actin and myosin slide across one another, causing the sarcomere to shorten. when enough sarcomeres shorten, the muscle contracts.

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cross-bridge

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myosin heads, club-shaped ends of a myosin molecule that bind to actin filaments and can swivel, causing actin filaments to slide past hte myosin filaments, which causes muscle contraction.

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troponin

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a protein on teh thin (actin) filaments in muscle cells that works with tropomyosin to prevent actin and myosin from binding in the abscence of calcium ions.

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tropmysin

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a protein on the thin (actin) filaments in muscle cells that works with troponin to prevent actin and myosin from binding in the abscence of calcium.

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sarcoplasmic reticulum

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an elaborate form fo smooth endoplasmic reticulum found in muscle fibers. it takes up, stores, and releases calcium ions as needed in muscle contraction.

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transverse tubules

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T tubles. The tiny, cylindrical inpocketings of the muscle fiber's plasma membrane that carry nerve impulses to almost every sarcomere.

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neuromuscular junction

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the area of contact between the terminal end of motor neuron and the sarcolemma of a skeletal muscle fiber. when an action potential reaches the terminal end of the motor neuron, acetylcholine is released, triggering events that can lead to muscle contraction.

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motor unit

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a motor neuron specialized to carry information away from the central nervous system to an effector, either a muscle or a gland.

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muscle twitch

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contraction of a muscle in response to a single stimulus.

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summation

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a phenomenon that results when a muscle is stimulated to contract before it has time to completely relax from a previous contraction. the response to each stimulation builds on the previous one.

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tetanus

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a smooth, sustained contraction of muscle caused when stimuli are delivered in such rapid succession that there is no time fo rmuscle relaxation.

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oxygen debt

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the amount of oxygen required after exercise to oxidize the lactic acid formed during exercise.

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slow-twitch cells

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muscle fibers that are specialized to contract slowly but with incredible endurance when stimulated. they contain an abundant supply of myoglobin and mitochondria and are richly supplied with capillaries. they depend on aerobic pathways to generate adenosine triphosphate (ATP) during muscle contraction.

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fast-twitch cells

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muscle fibers that contract rapidly and powerfullly, with little endurance. they have few mitochondria and large glycogen reserves. they depend on anaerobic pathways to generate adenosine triphosphate (ATP) during muscle contraction.