Term
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Definition
| The bundle of muscle fibers that each alpha motor neuron synapses with. |
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Term
| Slow Oxidative/Slow Twitch/Type 1 fibers |
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Definition
| Have several mitochondria, require O2 for extracting energy from fuel molecules, small diameter fibers. Dark in appearance because of high myoglobin. |
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Term
| Fast Oxidative/Type IIa fibers |
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Definition
| Fast twitch kinetics, large diameter, dependence on O2 |
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Term
| Fast glycolytic/Fast Twitch/Type IIb |
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Definition
| Large diameters, fast twitches, fatigue rapidly. No myoglobin, white in appearance. Lots of glycogen, and burn ATP without O2 using glycolysis. |
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Term
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Definition
| At high stimulation frequencies, force level is high and constant than that of a single twitch. Level is sustained due to sustained intracellular Ca2+ level. |
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Term
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Definition
| Force output of the muscle is greatly reduced. Possible causes: loss of O2, lactic acid buildup. |
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Term
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Definition
| Less load=faster shortening, more load=slower shortening. |
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Term
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Definition
| Muscle shortening against a constant load |
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Term
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Definition
| Muscles contract without shortening. ie: holding pencil. |
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Term
| Length-Tension Relationship |
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Definition
| Striated muscles have optimal length for isometric force generation. |
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Term
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Definition
| Thin filament that provides track for myosin to move along. |
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Term
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Definition
| Thick filament with cross bridges that "crawl" along actin to produce movement. |
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Term
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Definition
| Striped appearance characteristic of skeletal muscle due to high organization of actin and myosin. |
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Term
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Definition
| Region of contractile unit where actin and myosin filaments overlap each other. Dark bands. |
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Term
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Definition
| Light regions where only actin is present. |
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Term
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Definition
| Dark line in the center of the I Band where actin filaments are anchored. |
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Term
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Definition
| Unit of contractile function between two adjacent Z lines. |
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Term
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Definition
| In the center of the sarcomere, where the myosin filaments are anchored. |
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Term
| Sliding Filament Mechanism |
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Definition
| Sarcomere shortens as a result of the thick and thin filaments sliding past one another. |
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Term
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Definition
| Area in center of sarcomere where myosin does not overlap. |
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Term
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Definition
| Regulatory protein that sterically blocks the site on actin to which myosin binds. |
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Term
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Definition
| Can alter position of tropomyosin. Has Ca2+ binding site, when bound, tropomyosin moves, allows myosin to interact with actin. |
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Term
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Definition
| Troponin/tropomyosin contraction regulation. |
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Term
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Definition
| Myosin heads that bind to actin to allow the myosin to "crawl" along the actin. |
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Term
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Definition
| The process wherein the binding of and hydrolysis of ATP causes the myosin cross bridges to bind to the actin and "crawl" along the actin. |
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Term
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Definition
| The rotation of the cross bridge during the cross-bridge cycle. |
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Term
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Definition
| The stiffening of muscles after death when there is no ATP left to disengage the cross bridges. |
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Term
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Definition
| A contractile response to a single action potential. |
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Term
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Definition
| Where Ca2+ is stored in muscle cells. Analogous to ER in non-muscles cells. |
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Term
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Definition
| Invaginations in the sarcomeres that allow Ca2+ to reach deep into the interior of the contractile apparatus. |
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Term
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Definition
| Moves 2 Ca2+ ions into sarcomeres for every ATP hydrolyzed. |
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Term
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Definition
| The movement of contents through hollow organs as a result of the alternating contractions of the two smooth muscle layers. |
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Term
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Definition
| Anchoring areas for thin filaments in smooth muscle, and couple adjacent cells together. |
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Term
| Length-Tension Relationship (Smooth Muscle) |
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Definition
| Optimal length for force development, but greater range of lengths than skeletal muscle. |
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Term
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Definition
| Upon Ca2+ binding, it activates an enzyme called myosin light chain kinase (MLCK) |
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Term
| Myosin Light Chain Kinase (MLCK) |
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Definition
| Phosphoylates myosin regulatory subunits called light chains. |
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Term
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Definition
| Subunit of myosin whose activation signals that myosin and actin can interact. |
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Term
| Myosin Light Chain Phosphatase |
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Definition
| Removes phosphate group from light chain to shut off cross-bridge cycling and allow relaxation. |
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Term
| Thick Filament Regulation |
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Definition
| Ca2+ regulation that occurs in thick filament in smooth muscle rather than thin filaments in striated muscles. |
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Term
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Definition
| Cross-bridge cycling is reduced by low ATP consumption. This maintains smooth muscle tension over porlonged periods. |
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Term
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Definition
| Short, twitch-like contractions. |
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Term
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Definition
| Long sustained contractions, common in airways and blood vessels. |
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Term
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Definition
| Individual cells linked by gap junctions, electrically coupled. Have pacemaker potential and can spread to other regions. |
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Term
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Definition
| Do not propagate APs. Individual cells contract independently. |
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Term
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Definition
| Fight or flight. Increased heart rate, increased blood pressure, blood vessel dialation, airway dialation, glucose mobilization, pupil dialation, lens flattening, sweating, inhibition of digestive and urinary activity. |
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Term
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Definition
| Rest and digest. Day to day activities, quiet relaxation. Digestion and urination, "useful" saliva, pupils constrict. |
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Term
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Definition
| Carry impulses from CNS to ganglion. Short in the sympathetic, long in the parasympathetic. |
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Term
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Definition
| Fibers that carry impulses from the ganglion to target organs. Long in the sympathetic, short in the parasympathetic. |
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Term
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Definition
| Primary NT released in sympathetic branch. Produced in adrenal gland. |
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Term
| Alpha-adrenergic receptors |
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Definition
| Norepinephrine receptors found in vascular smooth muscle. Coupled with phospholipase C. Binding causes smooth muscle contraction by IP3 mediated release of Ca2+ from SR. |
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Term
| Beta-andrenergic receptors |
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Definition
| Found in heart. NE binds to receptors in heart and causes contractality. |
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