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KIN: Muscular Consid

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Question
Answer
Approximately how many muscles are in the adult human?   660  
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How much of one's body weight is from skeletal muscle   45%  
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What percentage of skeletal muscle is water?   75%  
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Skeletal muscle is surrounded by what?   Epimysium  
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Epimysium contains what?   Muscle fasicles  
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What are muscle fascicles surrounded by?   Perimysium  
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What does perimysium contain?   Muscle fibers  
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What are muscle fibers surrounded by?   Endomysium  
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What does endomysium contain?   Myofibrils  
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What are myofibrils composed of?   Sarcomeres  
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What do sarcomeres contain?   Dark, thick myosin and light, thin actin  
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During a contraction, overlapping myosin and actin filaments repeadtedly form cross-bridges to slide actin filaments towards the center of myosin which is called what?   M line  
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How is the physiologic cross-sectional area of a muscle measured?   Perpendicular to muscle fibers  
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What is the angle of pennation?   Angle at which individual fibers are oriented  
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What is the pennation angle of most human muscles?   0-30 degrees  
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How do the fibers in a fusiform muscle run?   Parallel along the muscles length  
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What is the shape of fusiform muscles?   Wide in the middle and tapered at the end  
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How is the anatomic cross-sectional area of a muscle measured?   Longitudinal axis of the muscle  
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Characteristics of fusiform muscles   Straight, PCSA = ACSA, increased velocity, decreased max force  
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Characteristics of pennate muscles   Angled, PCSA > ACSA, decreased velocity, increased max force  
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What are examples of fusiform muscles?   Sternocleidomastoid, rectus abdominis, biceps brachii  
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What are some examples of pennate muscles?   Semimembranosus (unipennate), gastroc (bipennate), deltoid (multipennate)  
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What are the 4 properties of muscles?   Irritability Contractibility Extensibility Elasticity  
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What is irritability?   The ability of a muscle to respond to stimulation; muscle is stimulated by chemical neurotransmitters  
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What is the only tissue more sensitive to muscle tissue?   Nerve tissue  
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What is contractibility?   Ability to shorten when sufficient stimulation is received  
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What is extensibility?   Ability to lengthen out or stretch beyond resting length  
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What is extensibility determined by?   Connective tissue found in perimysium, epimysium, and fascia surrounding a muscle  
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What is elasticity?   Ability to return to resting position once stretch is removed  
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What is elasticity determined by?   Connective tissue  
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What's the difference between muscle spindles and GTOs?   Location  
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Muscle is excited by impulses from what?   Alpha motor neurons  
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What are series elastic components?   Tissues that lie in series with the active proteins (titin)  
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What are parallel elastic components?   Noncontractile tissues in parallel with the active proteins (perymysium)  
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What are the 3 type of motor units?   Fast fatigable (Type IIX) Fast fatigue-resistance (Type IIA) Slow (Type I)  
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What is the recruitment order for motor units?   Type I, Type IIA, Type IIX  
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What is the order of recovery after exercise from slowest to fastest?   Type IIX, Type IIA, Type I  
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If tension is generated at a slow rate, where would the injury most likely occur?   Tendon-bone junction  
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If the tension is generated at a fast rate, where would the injury most likely occur?   Within a tendon  
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What are the functions of muscles?   Movement production Position maintenance Joint stabilization Support/protect viscera Control body entrance/exits Produce head  
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What is an agonist?   Muscle that actively contracts to produce a desired movement (AKA: Prime mover)  
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What is a stabilizer?   Muscle acting on a segment to allow motion at an adjacent joint to occur  
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What is a neutralizer?   Muscle that contracts to eliminate an undesired joint action of another muscle  
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What is an antagonist?   Muscle that acts in opposition to another  
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What is a synergist?   Muscle that cooperates with another to produce a desired movement  
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According to the force-velocity curve, during a concentric contraction, as the load increases the maximal contraction velocity of a muscle does what?   Decreases  
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According to the force-velocity curve, during an eccentric activation, speed of lengthening does what as a greater load is applied?   Increases  
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What is the take home message regarding the force-velocity curve during a concentric contraction?   The slower you go (to a point) the more force you can produce  
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What is the take home message regarding the force-velocity curve during an eccentric contraction?   At maximum lengthening velocity is when you will produce the most amount of force  
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What muscle fibers enhances power?   Fast-twitch fibers  
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What is the stretch-shortening cycle?   When a concentric contraction is preceded by an eccentric contraction (Plyometrics)  
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By doing a concentric contraction preceded by an eccentric contraction, what does this allow once to do?   Generate greater force  
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How does the stretch-shortening cycle work?   At the end of a pre-stretch, concentric muscle acivity is enhanced by stored elastic energy  
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How long is the stored energy good for before the shortening cycle?   0-.9 secs  
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If the stored elastic energy is lost, what happens to it?   Converted to heat  
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What is strength?   Max force or power produced by a muscle or muscle group during a maximal voluntary effort  
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How are strength gains commonly quantified?   1RM  
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What is the SAID principle?   Specific adaptations to imposed demands  
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What does hypertrophy result from?   Increased protein synthesis within muscle fibers and therefore, an increase in the physiologic cross-sectional area of the muscle  
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What is hyperplasia?   Increase in the actual number of fibers  
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Where else can you see strength gains from?   Nervous system more towards the beginning  
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How does tension build during passive stretch?   As an exponential function  
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What is the ideal resting length of a muscle fiber or individual sarcomere?   Length that allows the greatest number of cross-bridges and therefore, the greatest potential force  
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What happens to the number of potential cross bridges as the sarcomere is lengthened OR shortened from it's resting length and what effect does this have on the muscle?   It decreases so that lesser amounts of active force are capable of being generated  
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What does the resulting active length-tension curve look like?   Inverted U-shape with its peak at the optimal resting length (90 degrees elbow flexion)  
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