Flashcard Set Preview
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| 1 |
Muscle cells capable of shortening and converting the chemical energy of ____ into ______ energy
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ATP; mechanical
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3 types of muscle
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cardiac, smooth, skeletal
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5 characteristics of muscle
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responsiveness, conductivity, contractility, extensibility, and elasticity
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Skeletal muscle
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voluntary, striated, attached to bones. Myofibers as long as 30 cm. Alters light and dark transverse...
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Fascicles
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myofibers bundled together
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perimysium
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separates each fascicle from neighboring ones
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epimysium
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outer edge of muscle, holds all fibers together; grade imperceptibily into connective tissue...
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characteristics of collagen (2)
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extensible and elastic; stretches slightly under tension and recoils when released (this protects...
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2 types of elastic components
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parallel components to parallel muscle cells; series components joined to ends of muscle
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| 10 |
muscle fiber nuclei; fused and unfused
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flattened inside cell membrane; fusion by multiple myoblasts during development; unfused satellite...
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Sarcolemma
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plasma membrane of a muscle fiber; has tunnel-like infoldings or transverse (T) tubules that...
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sarcoplasm
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cytoplasm; filled with myofibrils (bundle of myofilaments) and glycogen for stored energy and...
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sarcoplasmic reticulum
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smooth ER; network around each myofibril; dilated end-sacs (terminal cisternea) that store...
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triad
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T tubule and 2 terminal cisternea
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myofilament
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bundle of parallel protein microfilaments
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3 types of myofilaments
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thick, thin, elastic
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| 17 |
thick filaments
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made of 200-500 myosin molecules; 2 entwined polypeptides (golf clubs); arranged in a bundle...
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central area
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bare zone with no heads in thick filaments
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thin filaments
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two intertwined strands of fibrous (F) actin; composed of globular (G) actin with an active...
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tropomyosin
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held in groove of thin filaments; each block 6-7 active sites of G actin to prevent myosin...
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troponin
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calcium-binding molecule attached to each tropomyosin molecule
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| 22 |
Elastic filaments
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composed of springy protein called titin; anchor each thick filament to Z disc. Prevents over...
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contractile proteins
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myosin (thick filaments) and actin (thin filaments); do the work of shortening the muscle fiber
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| 24 |
regulatory proteins
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tropomyosin and troponin; switch that starts/stops shortening of muscle cell; contraction activated...
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A band
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thick filament region; lighter, central H band area contains no thin filaments
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I band
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thin filament region; bisected by z disc protein connectin, anchoring elastic and thin filaments
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Muscle cells shorten because their ____ shorten
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individual sarcomeres; (pull z discs closer together)
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Neither thick or thin filaments change in length during shortening T/F?
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True
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skeletal muscle must be stimulated by ___ or it won't contract
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a nerve
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| 30 |
cell bodies of somatic motor neurons are found _____
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brainstem and spinal cord
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| 31 |
somatic motor fibers
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axons of somatic motor neurons; lead to skeletal muscles with each terminal branch supplying...
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motor unit
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each motor neuron and all the muscle fibers it innervates; dispersed throughout muscle causing...
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postural control
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ability to sustain long-term contraction as motor units take turns resting
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Fine control
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small motor units contain as few as 20 muscle fibers per nerve fiber (i.e. eye muscles)
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strength control
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gastrocnemius muscle has 1,000 fiber per nerve cell
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neuromusclar junction (synapse)
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functional connection between nerve fiber and muscle cell
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synaptic cleft
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tiny gap between nerve and muscle cells
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acetycholine/ACh
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neurotransmitter released from nerve fiber that stimulates muscle cell
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synaptic knob
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swollen end of nerve fiber; contains ACh in synaptic vesicles
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junctional folds of sarcolemma
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increase surface area for ACh receptors; contain acetycholinesterase that breaks down ACh and...
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| 41 |
basal lamina
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thin layer of collagen and glycoprotein over all of muscle fiber
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pesticides
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cholinesterase inhibitors; binds to acetycolinesterase and prevents it from degrading ACh;...
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tetanus/lockjaw
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spastic paralysis caused by toxin of Clostridium bacteria; blocks glycine release in the...
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Flaccid paralysis
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limp muscles; due to curare that competes with ACh; respiratory arrest
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resting membrane potential due to ___ outside of cell and ___ inside of cell
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Na+ outside of cell; K+ (and other ions) inside the cell
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resting membrane potential
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difference in charge across the membrane (-90mV cell)
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stimulation opens ion gates in membrane...
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Na+ rushes into cell, K+ rushes out of cell
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| 48 |
action potential
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quick up-and-down voltage shift; (from negative RMP to a positive value and then back to negative)
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| 49 |
4 actions involved in muscle contraction and relaxation
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excitation, excitation-contraction coupling, contraction, relaxation
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| 50 |
excitation
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nerve action potentials lead to action potentials in muscle fiber
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5 steps in excitation
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nerve signal opens voltage-gated calcium channels; Calcium stimulate exocytosis of synaptic...
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4 steps in excitation-contraction coupling
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action potential spreading over sarcolema enters T tubules; voltage-gated channels open in...
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4 steps in contraction
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myosin ATPase in myosin head hydrolyzes and ATP molecule, activating the head and cocking it...
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5 steps of relaxation
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nerve stimulation ceases and acetylcholinesterase remove ACh from receptors; stimulation of...
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rigor mortis
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stiffening of the body 3-4 hours after death; deteriorating SR releases Ca; Ca activates myosin-actin...
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length-tension relationship
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amount of tension generated depends on length of muscle before it was stimulated
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overly contracted
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weak contraction results; thick filaments too close to Z discs and can't slide
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too stretched
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weak contraction results; little overlap of thin and thick filaments doesn't allow for very...
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| 59 |
optimum resting length
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produces greatest force when muscles contract; CNS maintains optimal length producing muscle...
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threshold
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voltage producing an action potential; a single brief stimulus at that voltage produces a quick...
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3 phases of a twitch contraction
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latent period, contraction phase, and relaxation phase
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latent period
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delay; only internal tension is generated; no visible contraction occurs since only elastic...
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contraction phase
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external tension develops as muscle shortens
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relaxation phase
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loss of tension and return to resting length as calcium returns to SR
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multiple motor unit summation
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bringing more motor units into play/recruitment; i.e. lift a glass of milk versus a gallon...
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twitch
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low frequency (up to 10 stim./sec), produces an identical twitch response
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treppe
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moderate frequency (10-20 stim./sec); each twitch has time to recover but develops more tension...
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temporal or wave summation
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higher frequency stimulation (20-40/sec) generates gradually more strength of contraction;...
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complete tetanus
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maximum frequency (40-50/sec); muscle has no time to relax at all; twitches fuse into smooth,...
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isometric muscle contraction
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develops tension without changing length; important in postural muscle function and antagonistic...
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isotonic muscle contraction
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contraction with a change in length but no change in contraction
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concentric isotonic contraction
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tension while shortening
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eccentric isotonic contraction
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tension while lengthening
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| 74 |
pathways of ATP synthesis (2)
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anaerobic fermentation and aerobic respiration
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anaerobic fermentation
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ATP production limited; without oxygen, produces toxic lactic acid
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| 76 |
aerobic respiration
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more ATP produced; requires continuous oxygen supply, produces H2O and CO2
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immediate energy needs
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short, intense exercise (i.e. 100 m dash); oxygen need is supplied by myoglobin
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Phosphagen system
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myokinase transfers Pi groups from ADP to make ATP; creatine kinase transfers Pi groups from...
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short term energy needs
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glycogen-lactic acid system takes over; produces ATP for 30-40 seconds of maximum activity...
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| 80 |
long term energy
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aerobic respiration needed for prolonged exercise; produces 36 ATP/glucose molecules; after...
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fatigue
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progressive weakness of muscles from prolonged use; ATP synthesis declines as glycogen is consumed;...
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| 82 |
Endurance
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ability to maintain high-intensity exercise >5 mins; determined by maximum oxygen uptake
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| 83 |
maximum oxygen uptake (VO2 max)
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proportional to body size, peaks at age 20, larger in trained athlete and males
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| 84 |
carbohydrate loading
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used by some athletes; packs glycogen into muscles; adds water at the same time (2.7g h20 with...
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oxygen debt
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heaving breathing after strenuous exercise;
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| 86 |
4 purposes oxygen debt used for
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replaces oxygen reserves; replenishes phosphagen system, reconverts lactic acid to glucose...
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| 87 |
slow oxidative, slow twitch fibers
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more mitochondria, myoglobin, and capillaries; adapted for aerobic respiration and resistance...
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fast glycolytic, fast twitch fibers
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rich in enzymes for phosphagen and glycogen-lactic acid system; SR releases calcium quickly...
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| 89 |
resistance training
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weight lifting; stimulates cell enlargement due to synthesis of more myfilaments
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| 90 |
endurance training
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aerobic training; produces an increase in mitochondria, glycogen, and density of capillaries
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| 91 |
strength of contraction
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muscle size and fascicle arrangement; 3-4 kg/cm2 of cross sectional area; size of motor units...
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| 92 |
smooth muscle
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fuisform cells with one nucleus; no striations, sarcomeres, or z discs; thin filaments attach...
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Multiunit smooth muscle
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largest arteries, iris, pulmonary air passages; terminal nerve branches synapse on myocytes;...
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single unit smooth muscle
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most blood vessels and viscera as circular and longitudinal muscle layers; electrically coupled...
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| 95 |
excitability
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ability for cell to respond to a stimulus, especially the ability of nerve and muscle cells...
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| 96 |
contractility
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ability to shorten; amount of force that a contracting muscle fiber generates for a given stimulus
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| 97 |
origin
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where attached to bone, doesn't move
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| 98 |
insertion
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attached to joint, etc, and is moveable
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| 99 |
prime mover
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the muscle primarily responsible for a given joint action
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| 100 |
antagonist
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muscle that opposes the prime mover/agonist at a joint
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| 101 |
fixator
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holding base solid : ie moving shoulder, fixator
muscles allow scapula to stay in place;...
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| 102 |
synergist
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muscle that works with prime mover/agonist to assist
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