Muscle tissue
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| skeletal muscles maintain __ | posture
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| skeletal muscles __ joints | stabilize
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| skeletal muscles generate __ | heat
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| skeletal muscles __ __ but tires easily | contracts rapidly
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| in skeletal muscles, each muscle is a(n) | organ composed of muscle tissue, blood, & connective tissue
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| striated; involuntary; responsible for pumping blood through body; specialized muscle | cardiac muscle
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| cardiac muscle contracts at steady rate set by __ __ | heart’s pacemaker
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| neural controls, in cardiac muscles | allow heart to respond to changes in body needs
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| spindle-shaped cells w/1 centrally located nucleus; no externally visible striations; involuntary; forces food, feces & other substances through internal body channels | smooth muscles
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| smooth muscles are found | walls of hollow visceral organs, such as stomach, urinary bladder, & respiratory passages
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| ability to recoil & resume resting length after being stretched | elasticity
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| ability to be stretched/extended | extensibility
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| muscle cell's ability to move by shortening | contractility
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| ability to respond to stimuli | excitability
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| most skeletal muscles __ __ & are attached to bone in at least __ places | span joints; two
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| attachment of a muscle that remains relatively fixed during muscular contraction | muscle’s origin
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| epimysium of muscle is fused to periosteum of a bone/perichondrium of cartilage | direct or fleshy attachment
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| muscle's CT wrapping extends beyond muscle via tendons/aponeurosis | indirect attachment
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| sheath of CT surrounding each muscle fiber; consists of fine areolar CT | endomysium
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| connective tissue surrounding groups of fascicles | perimysium
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| dense irregular connective tissue that surrounds entire muscle | epimysium
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| sarcolemma | plasma membrane os muscle cell
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| each __ __ is a long, cylindrical cell with multiple nuclei just beneath sarcolemma | muscle fiber
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| sarcoplasm | cytoplasm of muscle cell
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| contains glycosomes & myoglobin; abundant mitochondria; usual organelles | sarcoplasm
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| myofibrils, sarcoplasmic reticulum, & T tubules are found in the muscle fiber's | cytoplasm
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| made of hundreds of myofibrils | muscle fiber (cell)
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| found within myofibril | striations, sarcomere & myofilaments
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| striations of myofibril are due to | arrangement of myofilaments
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| sarcomere is region of myofibril between 2 | Z discs
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| banding pattern produced by thick myosin & thin actin filaments | myofilaments
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| thin myofilaments; chiefly composed of the protein | actin
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| thick myofilaments composed of protein | myosin
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| each myosin molecule has | rod-like tail & 2 globular heads
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| two interwoven, polypeptide chains are found in myosin molecule's | tails
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| form cross bridges, found in myosin molecules | heads
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| subunits of thin myofilaments contain active sites to which | myosin heads attach during contraction
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| regulatory subunits bound to actin | tropomyosin & troponin
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| sarcoplasmic reticulum is elaborate smooth __ __ that runs longitudinally & surrounds each myofibril | endoplasmic reticulum
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| sarcoplasmic reticulum has paired terminal cisternae form | perpendicular cross channels
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| sarcoplasmic reticulum stores __ __ & releases them when muscle is stimulated to contract | calcium ions
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| extensions of sarcolemma, penetrate deep into cell’s interior | T tubules
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| T tubules associate w/paired terminal cisternae to form __ | triads
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| upon __ __, myosin heads bind to active sites on actin & sliding begins | nerve stimulation
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| thin filaments __ __ thick ones so that actin & myosin filaments __ to greater degree | slide past; overlap
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| in the __ __, thin & thick filaments overlap only slightly | relaxed state
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| as muscles relax, sarcomeres __ & muscle cell __ | shorten; shortens
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| stimulated by a nerve ending; electrical current or action potential is propagated along its sarcolemma; results in a rise in intracellular Ca2+ levels | skeletal muscle contraction
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| the final trigger for skeletal muscle contraction | rise in intracellular Ca2+ levels
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| sequence of events by which transmission of an action potential along the sarcolemma leads to the sliding of myofilaments; linking electrical signal to contraction is called | excitation-contraction coupling
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| skeletal muscles are stimulated by | motor neurons
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| __ of motor neurons branch as they enter muscles | axons
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| each __ __ forms a neuromuscular junction w/muscle fiber | axonal terminal
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| axon branch; folds of sarcolemma at motor end plate w/acetyl choline receptors; synaptic vesicles in axon terminal; synaptic cleft; are all components of a(n) | neuromuscular junction (NMJ)
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| __ __ reaches axon terminal at NMJ | nerve impulse
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| at NMJ, voltage-gated __ __ in axon terminal open, allowing __ enter axon | calcium channels; Ca++
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| at NMJ, Ca++ inside axon terminal causes synaptic vesicles to fuse with __ __ | axonal membrane
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| at NMJ, fusion of synaptic vessels w/axonal membrane releases ACh into synaptic cleft via __ | exocytosis
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| at NMJ, binding of ACh to its receptors on sarcolemma opens Na/K __ __ | gated channels
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| at NMJ, more Na+ diffuses in & interior of sarcolemma becomes less negative (depolarization), which initiates a(n) | action potential in muscle
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| at NMJ, ACh is quickly destroyed by __ acetylcholinesterase | enzyme
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| predominant extracellular ion is Na+; predominant intracellular ion is K+ | resting state
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| in resting cell inside of sarcolemma is | negative compared to outside
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| difference in charge of sarcolemma, negative compared to outside, is known as | resting membrane potential
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| action potential, depolarization, takes place when | ACh binds to its receptors on sarcolemma Na/K channels open
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| once ACh binds to its receptors on sarcolemma Na/K channels open, sodium channels open first- Na+ diffuses in & causes a patch of sarcolemma to become | less negative
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| change in resting potential is | depolarization
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| initially, depolarization, is a local electrical event called | end plate potential
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| if stimulus is strong enough, a(n) __ __ is initiated | action potential/propagation
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| if action potential initiated, voltage-gated Na+ channels open in adjacent areas of sarcolemma causing it to | depolarize
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| action potential travels | across sarcolemma
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| ultimately action potential results in | contraction of a muscle
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| in action potential/repolarization, sarcolemma permeability | changes
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| in action potential/repolarization, Na+ channels __ & K+ channels __ | close; open
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| in action potential/repolarization, K+ __ out from cell, restoring __ membrane potential (becoming negative again) | diffuses; resting
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| occurs in same direction as depolarization | repolarization
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| in excitation/contraction coupling, action potential propagates | along sarcolemma to T-tubules
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| in excitation/contraction coupling, action potential propagated along sarcolemma to T-tubules triggers | Ca2+ release from terminal cisternae
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| in excitation/contraction coupling, Ca++ bind to __; blocking action of tropomyosin released- actin binding sites __ | troponin; exposed
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| in excitation/contraction coupling, myosin heads attach forming a __ __; power stroke of myosin head causes sliding of __ __ toward center of sarcomere | cross bridge; thin filaments
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| binding of ATP to myosin heads results in their detachment from actin during | excitation/contraction coupling
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| during excitation/contraction coupling, as action potential ends, removal of Ca+2 by __ __ | active transport
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| stiffening of muscles after death; cross bridge detachment requires ATP | rigor mortis
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| because of lack of __ after breathing stops- actin & myosin irreversibly cross linked causing rigor mortis | ATP
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| refers to activation of cross bridges | contraction
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| force exerted by contracting muscle on an object | muscle tension
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| opposing force exerted on muscle by weight of object | load
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| occurs when tension generated by cross bridges exceeds forces opposing it | shortening
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| when cross bridges become inactive, tension declines & relaxation occurs | contraction ends
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| contraction in which muscle does not shorten (load is too heavy) but its internal tension increases; load not moved | isometric contraction
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| isometric contraction is used in | standing, sitting, posture
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| muscle changes in length; muscle tension overcomes load & moves load | isotonic contraction
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| isotonic contraction are used in | walking/moving any part of body
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| motor neuron & all muscle fibers it supplies | motor unit
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| muscles that control fine precise movements e.g. fingers, eyes (few muscle fibers) have | small motor units
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| large weight-bearing muscles (many muscle fibers) e.g. thighs, hips have | large motor units
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| muscle contraction in response to a single stimulus | muscle twitch
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| phase of a muscle twitch; first few m/sec after stimulus; no response seen yet | latent period
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| phase of a muscle twitch when cross bridges form | period of contraction
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| phase of a muscle twitch when Ca2+ re-enters SR; muscle tension decreases | period of relaxation
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| factor affecting muscle tension in which muscle stimulated rapidly, contractions are summed up become stronger | frequency of stimulation
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| factor affecting muscle tension in which the more the motor fibers are contracting (by recruitment of more motor units) the stronger the contraction | number of muscle fibers contracting
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| factor affecting muscle tension in which muscles contract strongest when muscle fibers are moderately stretched before contraction | degree of muscle stretch
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| degree of muscle stretch is optimum muscle length at which they can | generate maximum force of contraction
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| degree of muscle stretch, number of muscle fibers contracting, & frequency of stimulation | factors that affect muscle tension
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| single stimulus results in a single contractile response | a muscle twitch
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| with increased frequency of stimulus muscle does not relax completely; contraction force increasing | wave summation
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| shorter & shorter relaxation | incomplete tetanus
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| smooth continuous contraction without any relaxation | complete tetanus
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| produces weak contraction because overlapping thin filaments interfere with each other | unstretched sarcomere
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| cross bridges too far apart to cycle | overstretched sarcomere
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| maximum tension develops at this optimum overlap of thick & thin filaments; all cross bridges can cycle | moderately stretched sarcomere
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| constant, partial state of muscle contraction which does not produce active movements | muscle tone
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| muscle tone keeps muscles __ & ready to __ to stimulus | firm; respond
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| account for muscle tone by responding to stretch receptors in muscles & tendons | spinal reflexes
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| ATP in muscle contraction is used for energizing | power stroke of myosin head
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| ATP in muscle contraction is used for ___ myosin head from actin | detaching
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| ATP in muscle contraction is used for pumping __ back into sarcoplasmic reticulum | calcium
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| creatine phosphate (CP), anaerobic glycolysis of glucose, & aerobic respiration are sources of | ATP regeneration
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| during contraction: hydrolysisphosphate group combines w/ADP to form ATP (immediate source) | creatine phosphate (CP)
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| during contraction: when muscle contractile activity reaches 70% of maximum, bulging muscles compress blood vessels; impaired O2 delivery | anaerobic glycolysis of glucose
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| during contraction, largest amount of ATP formed | aerobic respiration
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| muscle is being stimulated but is in a state of physiological inability to contract | muscle fatigue
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| muscle fatigue can be due to __ ATP production | low
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| muscle fatigue can be due to __ __ accumulation | lactic acid
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| a functional characteristic of muscle fiber type, slow & fast fibers on basis of | speed of contraction
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| a functional characteristic of muscle fiber type, according to ATP-forming pathways | oxidative or glycolytic fibers
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| cells that rely on oxygen-using aerobic pathways for ATP generation | oxidative fibers
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| cells that rely more on anaerobic glycolysis pathways for ATP generation | glycolytic fibers
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| characteristics intermediate btwn oxidative & glycolytic fibers | fast oxidative fibers
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| red fibers; depend on aerobic ATP production; have more myoglobin, capillaries, mitochondria, low glycogen; contract slowly, are fatigue resistant & have high endurance | slow oxidative fibers
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| example of slow oxidative fibers | muscles maintaining posture; activities- running a marathon
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| white fibers; mainly use glycolysis for ATP production; large diameter fibers, have abundant glycogen, but few capillaries, mitochondria & low myoglobin; contract quickly, and are easily fatigued; muscles used for short time in powerful activities | fast glycolytic fibers
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| example of fast glycolytic fibers | hitting baseball, pushing piano
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| most muscles contain a(n) __ of fiber types | mixture
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| shrinkage of muscle due to decrease in size of cells | atrophy
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| example of disuse atrophy | immobilization
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| example of atrophy due to loss of nerve supply | paralysis
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| enlargement of a muscle; more capillaries & more mitochondria; greater bulk through increase in size, but not in number of cells | hypertrophy
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| example of hypertrophy | strenuous exercise in body builders
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| composed of spindle-shaped fibers w/central nuclei | smooth muscle
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| smooth muscle is found in | walls of blood vessels, digestive, urinary, respiratory & reproductive tracts
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| smooth muscle is organized in two layers of | sheets
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| organized sheets of smooth muscle are sheets of | longitudinal & circular
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| smooth muscle lack the __ __ junctions of skeletal muscle | structures neuromuscular
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| smooth muscles autonomic nerve fibers have __ that release neurotransmitters | varicosities
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| smooth muscle sarcoplasmic reticulum is | less developed
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| smooth muscle T tubules are | absent
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| in smooth muscle, actin & myosin filaments are present but | there are no sarcomeres
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| in smooth muscle, there is no | troponin complex
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| slow & prolonged; has low energy requirements | smooth muscle contraction
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| mostly whole sheets of smooth muscle contract together, because of __ __, as __ __ spread from cell to cell | gap junctions; action potentials
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| each skeletal muscle fiber is stimulated to __ by its own NMJ | contract
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| in smooth muscle, actin & myosin interact by the | sliding filament mechanism
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| in smooth muscle, final trigger for contractions is a(n) | rise in intracellular Ca2+
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| in smooth muscle, sliding filament mechanism | requires ATP
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| in smooth muscle, Ca2+ enter mainly from the __ __ | extracellular space
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| in smooth muscle, some Ca2+ is __ __ SR | released from
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| when stretched to an optimal length contract more strongly | cardiac & skeletal muscles
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| smooth muscle responds to stretch briefly by __ __ then adapts to its new length & relaxes | increased contraction
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| enables organs such as the stomach and bladder to be able to store contents without strong contractions expelling contents | stress-relaxation response of smooth muscles
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| found in walls of hollow visceral organs; cells contract as a unit (have gap junctions); arranged in sheets; show stress-relaxation response | smooth muscle single unit
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| found in airways, large arteries, internal eye muscles; have individual NMJs & muscle fibers independent of each other | smooth muscle multiunit
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| increase in cell numbers | hyperplasia
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| smooth muscles can undergo hyperplasia | when stimulated
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| examples of smooth muscle hyperplasia stimulation is | estrogen’s effect on the uterus
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| during pregnancy, estrogen stimulates uterine growth to accommodate the increasing size of the growing fetus, causing | smooth muscle hyperplasia
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| because skeletal & smooth muscles are __ they are called muscle fibers | elongated
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| whenever you see prefixes myo-/mys- or sarco- the reference is to | muscle
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| word root means muscle | myo-/mys-
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| word root means flesh | sarco-
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| word root means husk | -lemma
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| muscle composed of cylindrical, multinucleate cells w/obvious striations; attached to skeleton; voluntary muscle | skeletal muscle tissue
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| skeletal muscle tissue is packaged; organs that attach to & cover bony skeleton; responsible for body movements | skeletal muscles
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| cardiac muscles tissue constitutes bulk of __ __ | heart walls
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| allow heart to speed up for brief periods of exertion | neural controls
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| response to stimuli; generation of electrical impulse that passes along plasma membrane of muscle cell & causes cell to contract | conductivity
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| produces movement, maintains posture, stabilizes joints, generates heat, etc. | muscle functions
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| skeletal muscles are responsible for all __ & __ | locomotion; manipulation
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| skeletal muscles enable you to __ __ to changes in external environment | respond quickly
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| cardiac muscle of heart & smooth muscle in walls of blood vessels help to | maintain blood pressure
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| skeletal muscles account for at least 40% of | body mass
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| skeletal muscles are muscle type most responsible for | generating heat
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| form valves to regulate passage of substances through internal body openings, dilate/constrict pupils of eyes, & forms arrector pili muscles attached to hair follicles | smooth muscles
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| predominately muscle fibers, but also blood vessels, nerve fibers, & CT | composition of skeletal muscles
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| in general, __ __ is served by one nerve, artery, & 1/more veins | each muscle
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| only cardiac & smooth muscles can | contract in without nerve stimulation
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| long & winding w/numerous cross-links, which is feature that accommodates changes in muscle length | muscle capillaries
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| muscle capillaries __ when muscle is stretched | straighten
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| muscle capillaries __ when muscle contracts | contort
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| support each muscle cell & reinforce muscle as a whole; prevents bulging muscle from bursting during strong contractions | CT sheaths
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| bundle of nerve/muscle fibers bound together by CT | fascicles
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| CT sheaths contribute to __ of muscle tissue | elasticity
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| CT sheaths provide entry & exit routes for | blood vessels & nerve fibers serving muscle
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| movable attachment of a muscle | muscle's insertion
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| when muscle contracts movable bone, __ moves towards immovable/less movable bone | insertion
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| cord of dense fibrous tissue attaching muscle to bone | tendon
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| fibrous/membranous sheet connecting muscle & part it moves | aponeurosis
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| anchors muscle to CT covering of skeletal element or fascia of other muscles | aponeurosis/tendon
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| indirect attachments are more common because of | their durability & size
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| more __ than fleshy muscle can pass over __ | tendons; joint
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| granules of stored glycogen that provide glucose during periods of muscle cell activity | glycosomes
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| oxygen-binding, red pigment in muscle | myoglobin
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| myoglobin is similar to | hemoglobin
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| rod-like bundle of contractile filaments (myofilaments) found in muscle fibers (cells) | myofibril
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| myofibrils account for about 80% of | cellular volume
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| repeating series of dark & light bands, evident along length of each myofibril | striations
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| dark striations within muscle cells | A bands
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| light striations within muscle cells | I bands
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| lighter region in midsection of A band | H zone
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| dark line that bisects each H zone vertically; formed by molecules of protein myomesin | M line
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| darker, midline interruption in I bands; coin-shaped sheet composed largely of protein alpha-actinin; anchors thin filaments | Z disc
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| smallest contractile unit of muscle; extends from 1 Z disc to next | sarcomere
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| sarcomere is __ __ of skeletal muscle | functional unit
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| sarcomere contains __ band flanked by 1/2 __ band | A; I
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| located in center; contain myosin; extend entire length of A band | thick filaments
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| more lateral; contain actin; extend across I band & partway into A band | thin filaments
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| contain desmin; extend from Z disc; connect each myofibril to next throughout width of muscle cell | intermediate filaments
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| consists of 2 heavy & 4 light polypeptide chains; has rod-like tail attached by flexible hinge to 2 globular heads | myosin molecule
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| rod-shaped protein, spiral about actin core & hep stiffen & stabilize it | tropomyosin
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| in relaxed muscle fiber, tropomyosin __ myosin-binding sites on actin | block
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| globular, three-polypeptide complex | troponin
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| troponin & tropomyosin help control __ __ involved in contraction | myosin-actin interactions
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| composed of titin | elastic filament
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| protein extending from Z disc to thick filament, & then runs within thick filament to attach to M line | titin
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| titin forms __ of thick filament | core
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| titin holds thick filaments in place, thus maintaining | organization of A band
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| titin holds thick filaments in place, helping muscle cell to | spring back into shape after being stretched
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| titin does not resist stretching in | ordinary range of extension
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| titin stiffens as it uncoils, helping muscle to | resist excessive stretching
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| structural protein that links thin filaments to integral proteins of sarcolemma | dystrophin
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| nebulin, myomesin, & C proteins are other proteins that act to | bind filaments or sarcomeres together & maintain their alignment
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| SR & T tubules are two sets of intracellular tubules that | participate in regulation of muscle contractions
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| tubules of SR run longitudinally along | myofibril communicating at H zone
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| major role of SR is to regulate | intercellular levels of ionic calcium
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| T tubules increase muscle fiber's __ __ | surface area
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| successive groupings of 2 membranous structures (terminal cisterna, T tubule, & terminal cisterna | triads (definition)
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| because T tubules are extensions of sarcolemma they | conduct impulses to deepest regions of muscle cell to every sarcomere
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| protruding integral proteins of T tubules act as | voltage sensors
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| form gated channels through which Ca2+ can be released from SR cisternae | foot proteins
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| term contraction refers to | activation of myosin's cross bridges
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| states that during contraction thin filaments slide past thick ones so that actin & myosin filaments overlap to greater degree | sliding filament model of contraction
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| for skeletal muscle to contract it must be | stimulated by nerve ending so change in membrane potential occurs
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| large transient depolarization event, including polarity reversal, that is conducted along membrane of muscle cell/nerve fiber | action potential
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| for skeletal muscle to contract it must be activated, then must | generate & propagate action potential along its sarcolemma
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| for skeletal muscle to contract it must be activated, generate/propagate action potential, then final trigger is | short-lived rise in intracellular calcium ion levels
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| nerve cells that activate skeletal muscle fibers are called | somatic motor neurons
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| long thread-like extensions of somatic motor neurons | axons
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| synaptic connection of axon of motor neuron with muscle fiber | neuromuscular junction
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| when axon of motor neuron divides when entering muscle, the short curling branches it gives off are collectively called | elliptical neuromuscular junctions
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| each muscle fiber has | only one neuromuscular junction
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| fluid-filled (with ACh) space at a synapse | synaptic cleft
🗑
|
||||
| chemical transmitter substance released by some nerve endings; neurotransmitter | acetylcholine (ACh)
🗑
|
||||
| trough-like part of muscle fiber's sarcolemma | junctional folds
🗑
|
||||
| junctional folds provide __ __ __ for location for millions of ACh receptors | large surface area
🗑
|
||||
| neuromuscular junction includes | axonal endings, synaptic cleft, junctional folds
🗑
|
||||
| enzyme present at NMJ & synapses that degrades acetylcholine & terminates its action | acetylcholinesterase
🗑
|
||||
| disease characterized by drooping upper eyelids, difficulty swallowing & talking, & generalized muscle weakness, involves shortage of ACh receptor | myasthenia gravis
🗑
|
||||
| resting sarcolemma is | polarized
🗑
|
||||
| loss of a state of polarity; loss/reduction of negative membrane potential | depolarization
🗑
|
||||
| depolarizations of skeletal muscle fibers caused by neurotransmitters binding to post-synaptic membrane in NMJ | end plate potential
🗑
|
||||
| movement of membrane potential to initial resting state | repolarization
🗑
|
||||
| period of time it takes for an excitable membrane to be ready for 2nd stimulus once it returns to its resting state following an excitation | refractory period
🗑
|
||||
| repolarization only restores __ __ of resting state | electrical conditions
🗑
|
||||
| ATP-dependent sodium-ion pump restores __ __ of resting state | ionic conditions
🗑
|
||||
| once initiated, the action potential is __ | unstoppable
🗑
|
||||
| events of excitation-contraction coupling take place during __ __ btwn action potential initiation & beginning of mechanical activity | latent period
🗑
|
||||
| intracellular Ca levels low & active (myosin-binding) sites on actin are physically blocked by tropomyosin | muscle is relaxed
🗑
|
||||
| tropomyosin is __ when sufficient Ca is present | removed
🗑
|
||||
| continues as long as Ca signal & adequate ATP are present | sliding of thin filament
🗑
|
||||
| when impulses delivered rapidly, intracellular Ca2_ levels __ __ due to successive rounds of Ca2_ released from SR | increase greatly
🗑
|
||||
| except for brief period following muscle cell __, Ca ion concentrations in cytosol are kept low | excitation
🗑
|
||||
| graphic recording of mechanical contractile activity produced by apparatus that measures muscle contraction | myogram
🗑
|
||||
| latent period | period of time btwn stimulation & onset of muscle contraction; excitation-contraction coupling occurs here
🗑
|
||||
| period of contraction | when cross bridges are active, from onset-peak tension development, myogram tracing rises to peak
🗑
|
||||
| period of relaxation | final phase; initiated by reentry of Ca2+ into SR
🗑
|
||||
| muscle twitches may result from | some neuromuscular problems
🗑
|
||||
| relatively smooth; vary in strength as different demands placed on them | healthy muscle contractions
🗑
|
||||
| variations in degree of muscle contraction by changing either frequency/strength of stimulus | graded muscle responses
🗑
|
||||
| nervous system achieves __ __ __ by increasing firing rate of motor neurons | greater muscular force
🗑
|
||||
| occurs in transmission of nerve impulses when volley of impulses arrives at synapse so that duration of impulses is briefer than post-synaptic potential & their deliveries of transmitter are combined to create larger than normal response | temporal/wave summation
🗑
|
||||
| each stimulus causes contraction to be initiated when muscle has only partly relaxed from previous contraction | unfused/incomplete tetanus
🗑
|
||||
| sustained muscular contraction caused by series of nerve stimuli repeated so rapidly that individual muscular responses are fused | complete tetanus
🗑
|
||||
| fused/complete tetanus happens __ in real world | infrequently
🗑
|
||||
| __ tetanus eventually leads to muscle __ | prolonged; fatigue
🗑
|
||||
| wave summation contributes to __ force | contractile
🗑
|
||||
| is to produce smooth, continuous muscle contractions by rapidly stimulating specific number of muscle cells | primary function of wave summation
🗑
|
||||
| smooth but steady increase in muscular tension produced by increasing number of active motor units | recruitment/multiple motor unit summation
🗑
|
||||
| stimulus too weak to evoke a response | subthreshold stimulus
🗑
|
||||
| one stimulus just strong enough to excite; weakest stimulus capable of producing response in irritable tissue | threshold stimulus
🗑
|
||||
| stimulus strong enough to evoke greatest possible response; represents point at which all muscle's motor units are recruited | maximal stimulus
🗑
|
||||
| increasing stimulus intensity beyond maximal stimulus | does not produce stronger contraction
🗑
|
||||
| recruitment process is __ by size principle | dictated
🗑
|
||||
| motor units of small, highly excitable motor neurons (found in smallest muscle fibers) tend to be activated first; as motor units w/larger & larger muscle fibers begin to excited, contractile strength increases | size principle
🗑
|
||||
| size principle dictates that largest motor units containing large, coarse muscle fibers controlled by largest least excitable neurons & are activated only when | most powerful contraction is necessary
🗑
|
||||
| size principle is important because it allows for increases in force during weak contractions to | occur in small steps
🗑
|
||||
| according to size principle, gradations in muscle force are __ __ when large amounts of force are needed | progressively greater
🗑
|
||||
| although all motor unit of a muscle may be recruited simultaneously to produce strong contraction, they are more commonly activated __ in body | asynchronously
🗑
|
||||
| even __ muscles are almost always __ | relaxed; contracted
🗑
|
||||
| muscle contraction that occurs while muscle is shortening as it develops tension & contracts to move resistance | concentric contraction
🗑
|
||||
| type of muscle contraction that occurs as muscle fibers lengthen; contractile force generated by muscle is weaker than opposing force, which causes muscle to stretch | eccentric contraction
🗑
|
||||
| eccentric contractions are about 50% __ __ than concentric ones | more forceful
🗑
|
||||
| eccentric contractions put body in position to | contract concentrically
🗑
|
||||
| CP-ADP reaction is catalyzed by | creatine kinase
🗑
|
||||
| initial phase of glucose breakdown; anaerobic pathways; glucose broken down into pyruvic acid molecules releasing enough energy to form small amount of ATP | glycolysis
🗑
|
||||
| 2 ATP produce | per glucose broken down
🗑
|
||||
| product of anaerobic metabolism, especially in muscle | lactic acid
🗑
|
||||
| lactic acid is produced when bulging muscles (from vigorous activity) compress blood vessels within them causing | impaired blood flow & O2 delivery
🗑
|
||||
| energy-yielding conversion of glucose to lactic acid in muscle, when sufficient oxygen is not available | anaerobic glycolysis
🗑
|
||||
| during __ __, lactic acid is end product of cellular metabolism of glucose | oxygen deficit
🗑
|
||||
| 95% of ATP used for muscle activity from from | aerobic respiration
🗑
|
||||
| when ATP demands are within capacity os aerobic pathway, light to moderate muscular activity can | continue for several hours in well-conditioned person
🗑
|
||||
| when exercise demands begin to exceed ability of muscle cells to carry out necessary reactions quickly enough, | glycolysis contributes more & more of total ATP generated
🗑
|
||||
| length of time muscle can continue to contract using aerobic pathways | aerobic endurance
🗑
|
||||
| point at which muscle metabolism converts to anaerobic glycolysis | anaerobic threshold
🗑
|
||||
| activities requiring surge of power lasting only few seconds (i.e. weight lighting, diving, etc.) rely | entirely on ATP & CP stores
🗑
|
||||
| more on-and-off or burst-like activities (i.e. tennis, soccer, etc.) appear to be fueled | almost entirely by anaerobic glycolysis
🗑
|
||||
| prolonged activities (i.e. marathons, jogging) where endurance over power is goal, depend | mainly on aerobic respiration
🗑
|
||||
| levels of CP & ATP do not change much during __ __ because ATP is generated at same rate it is use | prolonged exercise
🗑
|
||||
| states of continuous contraction because cross bridges are unable to detach | contractures
🗑
|
||||
| example of temporary contracture | writer's cramp
🗑
|
||||
| several __ __contribute to muscle fatigue | ionic imbalances
🗑
|
||||
| lactic acid is more important in provoking __ fatigue than __ fatigue | central; physiological
🗑
|
||||
| excessive intracellular accumulation of lactic acid raises concentration of H+ and alters __ __ | contractile proteins
🗑
|
||||
| lactic acid has been shown to __ high K+ levels, which do lead to muscle fatigue | counteract
🗑
|
||||
| intense exercise of short duration produces fatigue rapidly via disturbances that | alter E-P coupling
🗑
|
||||
| short-duration exercise damages SR, interfering with Ca2+ __ & __, and thus with muscle activation | regulation; release
🗑
|
||||
| O2-requiring muscle metabolism activities occur more slowly & are deferred until O2 is again available during | anaerobic muscle contraction
🗑
|
||||
| volume of O2 required after exercise to replenish stores of O_2, ATP, creatine phosphate, & glycogen & oxidize lactic acid formed during exercise | oxygen deficit (definition)
🗑
|
||||
| oxygen deficit represents difference btwn amount of oxygen __ for totally aerobic muscle activity & amount __ __ | need; actually used
🗑
|
||||
| only about 40% of energy released during muscle activity is | converted to useful work
🗑
|
||||
| greater muscle's __ __, more tension can develop & greater its strength | cross-sectional area
🗑
|
||||
| force generated by cross bridges, inside contracting muscle fibers | internal tension
🗑
|
||||
| force generated in extracellular fibers | external tension
🗑
|
||||
| length at which muscle can generate maximum force | optimal operating length
🗑
|
||||
| relationship btwn length of fiber & force that fiber produces at that length; permits sliding along nearly entire length of thin filaments | ideal length-tension relationship
🗑
|
||||
| in slow/fast fibers, difference in speed reflects how fast their myosin ATPases __ __ | split ATP
🗑
|
||||
| in slow/fast fibers, difference in speed reflects on pattern of __ __ of motor neurons | electrical activity
🗑
|
||||
| depending on pathways for forming ATP, skeletal muscles cells can be classified as | slow oxidative (SO), fast oxidative (FO), or fast glycolytic (FG) fibers
🗑
|
||||
| exercise that increases the need for oxygen | aerobic exercise
🗑
|
||||
| moderately weak but sustained muscle activity | endurance exercise
🗑
|
||||
| high-intensity exercise in which the muscles are pitted against high resistance or immovable forces and, as a result, muscle cells increase in size | resistance exercise
🗑
|
||||
| smooth muscle fibers run parallel to long axis of organ; when muscle contracts organ dilates & shortens | longitudinal layer
🗑
|
||||
| smooth muscle fibers run around circumference of organ; contraction constricts lumen causing it to elongate | circular layer
🗑
|
||||
| junction of varicosities & synaptic cleft of smooth muscle cells | diffuse junctions
🗑
|
||||
| epimysium | surround entire muscle
🗑
|
||||
| endomysium | surround each muscle fiber
🗑
|
||||
| perimysium | surround each muscle bundle
🗑
|
||||
| deep fascia | bind muscles into functional groups
🗑
|
||||
| sarcolemma | plasma membrane of skeletal muscle fiber
🗑
|
||||
| sarcoplasm | cytoplasm of a skeletal muscle fiber
🗑
|
||||
| sarcoplasmic reticulum | series of membranous channels (modified ER) that surround each myofibril
🗑
|
||||
| myofibril | rod-like contractile elements within a muscle fiber
🗑
|
||||
| sarcomere | functional unit of a skeletal muscle fiber
🗑
|
||||
| A band | area of the sarcomere with overlapping thick and thin filaments
🗑
|
||||
| I band | area of sarcomere containing only thin filaments
🗑
|
||||
| H band | are in center of A band containing only thick filaments
🗑
|
||||
| myosin molecules | cross bridges
🗑
|
||||
| synaptic knob | contains vesicles filled w/ACh
🗑
|
||||
| synaptic cleft | space btwn neuron & muscle
🗑
|
||||
| motor end plate | contains receptors for ACh
🗑
|
||||
| twitch | type of contraction represented by a single stimulus/contraction/relaxation sequence
🗑
|
||||
| incomplete tetanus | muscle producing peak tensions with visible relaxation during rapid cycles of contraction and relaxation
🗑
|
||||
| complete tetanus | muscle that is stimulated so frequently that the relaxation phase is completely eliminated
🗑
|
||||
| wave summation | when muscle is stimulated repeatedly for several seconds with a constant stimulus, the amount of tensions gradually increases to a maximum
🗑
|
||||
| endurance-type activities | best suited for slow oxidative fibers
🗑
|
||||
| 400M or 800M sprint | best suited for fast oxidative fibers
🗑
|
||||
| short-term intense movements | best suited for fast glycolytic fibers
🗑
|
||||
| skeletal muscle fibers | single, very long, cylindrical, multinucleate cells with striations
🗑
|
||||
| cardiac muscle cells | branching chains of cells; uni- or binucleate striations; intercalated discs
🗑
|
||||
| smooth muscle cells | single, fusiform, uninucleate; no striations
🗑
|
||||
| excitability | ability to receive and respond to a stimulus
🗑
|
||||
| contractility | ability to shorten forcibly when adequately stimulated
🗑
|
||||
| extensibility | ability to be stretched or extended
🗑
|
||||
| elasticity | ability of a muscle to resume its resting length after being stretched
🗑
|
||||
| isotonic contraction | contraction of muscle during which the muscle changes in length and the tension remains constant through most of the contractile period
🗑
|
||||
| isometric contraction | contraction of muscle during which the tension continues to increase but the muscle neither shortens nor lengthens
🗑
|
||||
| concentric contraction | contraction of the muscle in which the muscle shortens and does work
🗑
|
||||
| eccentric contraction | contraction of muscle in which the muscle contracts as it lengthens
🗑
|
||||
| skeletal muscle voluntary via __ __ of the somatic nervous system | axonal endings
🗑
|
||||
| involuntary; intrinsic system regulation, hormones and autonomic nervous system controls | cardiac muscles
🗑
|
||||
| involuntary, autonomic nerves, hormones, local chemicals | smooth muscles
🗑
|
||||
| acetylcholine (ACh) | neurotransmitter at the neuromuscular junction
🗑
|
||||
| creatine phosphate | high-energy compound in muscle
🗑
|
||||
| myoglobin | O2 storage molecules in muscles
🗑
|
||||
| lactic acid | product of anaerobic glycolysis
🗑
|
||||
| fast oxidative fibers | muscle fibers that contract quickly and rely on aerobic respiration for ATP
🗑
|
||||
| slow oxidative fibers | muscle fibers that are most resistant to fatigue
🗑
|
||||
| fast glycolytic fibers | muscle fibers that have few mitochondria
🗑
|
||||
| sustained spasm, or tetanic contraction | cramp
🗑
|
||||
| inflammation of a muscle, its connective tissue coverings and tendons, and capsules of nearby joints | fibromyositis
🗑
|
||||
| muscle pain resulting from any muscle disorder | myalgia
🗑
|
||||
| excessive stretching and possible tearing of a muscle caused by muscle overuse or abuse | strain
🗑
|
||||
| latent period | time btwn stimulus/electrical event & mechanical event of contraction
🗑
|
||||
| contraction period | time during which the muscle is shortening
🗑
|
||||
| relaxation period | time during which the muscle is returning to its original length
🗑
|
||||
| refractory period | very brief time after one stimulus during which the muscle is unresponsive to a second stimulus
🗑
|
||||
| action potential | propagation of an electrical current along sarcolemma
🗑
|
||||
| resting potential | initial polarized state
🗑
|
||||
| repolarization | restoration of membrane potential to resting potential
🗑
|
||||
| refractory period | time when fiber cannot be stimulated until repolarization is complete
🗑
|
||||
| end plate potential | electrical event occurring only at neuromuscular junction
🗑
|
||||
| Ca2+ | released by terminal cisternae into the sarcoplasm to bind with troponin
🗑
|
||||
| acetylcholinesterase | enzyme released into neuromuscular junction to break down acetylcholine
🗑
|
||||
| calmodulin | cytoplasmic, calcium-binding protein
🗑
|
||||
| electrical conditions of a resting sarcolemma | outside positive relative to the inside
🗑
|
||||
| depolarization & generation of action potential | production of an end plate potential at the motor end plate and consequent depolarization of adjacent areas
🗑
|
||||
| propagation of action potential | increased positive charge inside sarcolemma changes permeability of adjacent areas, opening voltage-regulated Na+ channels
🗑
|
||||
| repolarization | change in sarcolemma after the wave of depolarization; Na+ channels close and K+ channels open, allowing K+ to create a positive charge outside the membrane
🗑
|
||||
| producing movement | pulling on something to change its position
🗑
|
||||
| maintaining posture | development of tension to prevent movement, as in keeping the vertebral column upright
🗑
|
||||
| stabilizing joints | attaching to bones and keeping them in close proximity to one another
🗑
|
||||
| generation of heat | release of energy during metabolism
🗑
|
||||
| myosin | changes shape during the contraction cycle
🗑
|
||||
| actin | slides toward the M line during a contraction
🗑
|
||||
| tropomyosin | covers the binding site
🗑
|
||||
| troponin | binds Ca2+ and starts the contraction cycle
🗑
|
||||
| __ skeletal muscle is surrounded by epimysium | entire
🗑
|
||||
| as an axon enters a muscle, it branches into a number of axonal terminals, each of which forms a neuromuscular junction with a single muscle fiber. A motor neuron and all the muscle fibers it supplies is called a(n) | motor unit
🗑
|
||||
| What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges? | Ca2+
🗑
|
||||
| each skeletal muscle fiber is controlled by a neuron at a single | NMJ
🗑
|
||||
| terminal cisterna, transverse tubule, and terminal cistern | composition of the structure known as a triad in a skeletal muscle fiber
🗑
|
||||
| In the __ __ __ of muscle contraction, the myofilaments slide over each other, resulting in the overlapping of actin and myosin | sliding filament model
🗑
|
||||
| epimysium is the | dense layer of collagen fibers that surround an entire skeletal muscle
🗑
|
||||
| muscle tone | means a continued mild or partial contraction of an entire muscle is muscle
🗑
|
||||
| isometric | type of muscle contraction in which the muscle fibers produce increased tension, but the muscle neither shortens nor lengthens
🗑
|
||||
| lactic acid | substance that increases in quantity during repetitive muscle contraction
🗑
|
||||
| action potential | sequence of electrical changes that occurs along the sarcolemma when a muscle fiber is stimulated
🗑
|
||||
| calmodulin | binds calcium ions in a smooth muscle, causing contraction
🗑
|
||||
| sarcomere is part of | a myofibril
🗑
|
||||
| "cross bridges" that link between the thick and thin filaments are formed by the | globular heads of thick filaments
🗑
|
||||
| refractory period in which the muscle will not contract if stimulated occurs during | refractory period of muscle cell
🗑
|
||||
| cause of rigor mortis | calcium influx into the cell after death
🗑
|
||||
| 95% of the energy needed for contraction during moderate exercise | comes from ATOP
🗑
|
||||
| T-tubules | serve as a communication network that coordinates the contraction of each myofibril that makes up the muscle fiber
🗑
|
||||
| actin | myofilaments are composed chiefly of
🗑
|
||||
| when an action potential arrives at the neuromuscular junction, the most immediate result is | release of acetylcholine
🗑
|
||||
| if a muscle is applied to a load that exceeds the muscle's maximum tension | muscle length will not change during contraction
🗑
|
||||
| graded muscle response | variation of stimulation needed in skeletal muscle contraction in order to have controlled movement
🗑
|
||||
| aerobic respiration | most efficient means of producing ATP
🗑
|
||||
| if muscle became totally depleted of ATP | muscle would remain in a contracted state due to an inability to break actin-myosin cross bridges
🗑
|
||||
| smooth muscle depends on the __ system to regulate contraction | calcium-calmodulin
🗑
|
||||
| skeletal muscle relies on the __ __ system to regulate contraction | calcium-troponin
🗑
|
||||
| peristalsis | progressive, wavelike contractions that move foodstuffs through alimentary tube organs/move other substances through other hollow body organs
🗑
|
||||
| smooth muscle lacks highly structured, __ __ of skeletal muscles | specific NMJs
🗑
|
||||
| smooth muscles are controlled by | innervating nerve fibers, part of autonomic nervous system
🗑
|
||||
| varicosities | knob-like swellings of certain autonomic axons containing mitochondria and synaptic vesicles
🗑
|
||||
| diffuse junctions | wide synaptic cleft in general area of smooth muscles
🗑
|
||||
| smooth muscles have __ __ SR | less developed
🗑
|
||||
| some SR tubules of smooth muscle touch __ at several sites, forming what resembles __ | sarcolemma; half-triads
🗑
|
||||
| pouch-like infoldings that sequester bits of extracellular fluid containing high concentration of Ca2+ close to membrane | caveolae
🗑
|
||||
| when calcium channels in caveolae open, Ca2+ | influx occurs rapidly
🗑
|
||||
| in smooth muscles, SR does release some calcium that triggers contraction, but most | enters through the calcium channels
🗑
|
||||
| contraction of smooth muscle ends when calcium is | actively transported to SR & out of cell
🗑
|
||||
| smooth muscles contain | interdigitating thick & thin filaments
🗑
|
||||
| in smooth muscle, __ filament are fewer, but have __ __ along their entire length | thick; myosin heads
🗑
|
||||
| in smooth muscle, there is no __ __ in thin filaments | troponin complex
🗑
|
||||
| in smooth muscle, thick & thin filaments are __ __ allowing muscles to contract in __ __; thus peristalsis | arranged diagonally; twisting way
🗑
|
||||
| in smooth muscles, the lattice-like arrangement of non-contractile __ filaments attach to __ __ | intermediate; dense bodies
🗑
|
||||
| cytoplasmic structures; tethered to sarcolemma; act as anchoring points for thin filaments; correspond to Z discs of skeletal muscles | dense bodies
🗑
|
||||
| forms strong, cable-like intracellular cytoskeleton that harnesses pull generated by sliding of thick & thin filaments in smooth muscles | intermediate filament-dense body network
🗑
|
||||
| dense bodies, of smooth muscles, bind muscle cell to | endomysium & adjacent cells
🗑
|
||||
| synchronizistic contraction of smooth muscles reflects | electrical coupling by gap junctions
🗑
|
||||
| allow smooth muscles to transmit action potentials from fiber to fiber | gap junctions
🗑
|
||||
| some smooth muscles in stomach & small intestines are | pacemaker cells
🗑
|
||||
| smooth muscle's pacemaker cells have fluctuating __ __ & are __ | membrane potentials; self-excitatory
🗑
|
||||
| smooth muscle's pacemaker cells __ __ in absence of stimuli | depolarize spontaneously
🗑
|
||||
| rate & intensity of smooth muscle contraction may be modified by | neural & chemical stimuli
🗑
|
||||
| in order to phosphorylate myosin, calmodulin interacts with | myosin kinase/myosin light chain kinase
🗑
|
||||
| smooth muscle takes 30x longer to | contract & relax than skeletal muscle
🗑
|
||||
| smooth muscle myofilaments may __ __ during prolonged contractions, saving energy | latch together
🗑
|
||||
| smooth muscle cells may maintain __ __ even after dephosphorylation of myosin | latch state
🗑
|
||||
| __ __ of smooth muscle is extremely important to overall body homeostasis | ATP-efficient contraction
🗑
|
||||
| graded contraction depends on level of calcium and # of cross bridges formed | smooth muscle tone
🗑
|
||||
| smooth muscle makes ATP through __ __ | aerobic pathways
🗑
|
||||
| some smooth muscles respond to neural stimulation with __ __ only | graded potentials
🗑
|
||||
| smooth muscles react to __ __ in different ways depending on receptors present | different neurotransmitters
🗑
|
||||
| smooth muscles without nerve supply depolarize __ or in response to chemical stimuli that bind to __ __ receptors | spontaneously; G protein-linked
🗑
|
||||
| certain hormones, lack of O2, histamine, excess CO2, & low pH are different chemical factors that cause smooth muscle contraction & relaxation | without an action potential
🗑
|
||||
| smooth muscle responds differently to | stretch
🗑
|
||||
| smooth muscle can __ more than other muscle types | shorten
🗑
|
||||
| stretch of smooth muscle provokes contraction, but soon muscle | adapts to length & relaxes with retaining ability to contract on demand
🗑
|
||||
| lack of sarcomeres & irregular, overlapping arrangement of smooth muscle filaments allow them to | generate considerable force, even when they are substantially stretched
🗑
|
||||
| smooth muscle can contract when it is anywhere from | twice to half its resting length
🗑
|
||||
| smooth muscles are categorized as | single-unit or multiunit
🗑
|
||||
| type of smooth muscle; cells contract as unit & rhythmically, are electrically coupled by gap junctions; often exhibit spontaneous action potentials | visceral muscle
🗑
|
||||
| visceral muscle is also known as | single-unit smooth muscle
🗑
|
||||
| visceral muscle is found in walls of all hollow organs except | the heart
🗑
|
||||
| smooth muscles in large airways to lungs & in large arteries, arrector pili muscle attached to hair follicles, & internal eye muscles are examples of | multiunit smooth muscle
🗑
|
||||
| in multiunit smooth muscle | gap junctions are rare & spontaneous synchronous depolarization are rare
🗑
|
||||
| multiunit smooth muscle is innervated by | autonomic nervous system
🗑
|
||||
| embryonic mesoderm cells from which all muscle fibers develop | myoblasts
🗑
|
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You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
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Created by:
lfrancois
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