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KIN: Muscular Consid

Approximately how many muscles are in the adult human? 660
How much of one's body weight is from skeletal muscle 45%
What percentage of skeletal muscle is water? 75%
Skeletal muscle is surrounded by what? Epimysium
Epimysium contains what? Muscle fasicles
What are muscle fascicles surrounded by? Perimysium
What does perimysium contain? Muscle fibers
What are muscle fibers surrounded by? Endomysium
What does endomysium contain? Myofibrils
What are myofibrils composed of? Sarcomeres
What do sarcomeres contain? Dark, thick myosin and light, thin actin
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
How is the physiologic cross-sectional area of a muscle measured? Perpendicular to muscle fibers
What is the angle of pennation? Angle at which individual fibers are oriented
What is the pennation angle of most human muscles? 0-30 degrees
How do the fibers in a fusiform muscle run? Parallel along the muscles length
What is the shape of fusiform muscles? Wide in the middle and tapered at the end
How is the anatomic cross-sectional area of a muscle measured? Longitudinal axis of the muscle
Characteristics of fusiform muscles Straight, PCSA = ACSA, increased velocity, decreased max force
Characteristics of pennate muscles Angled, PCSA > ACSA, decreased velocity, increased max force
What are examples of fusiform muscles? Sternocleidomastoid, rectus abdominis, biceps brachii
What are some examples of pennate muscles? Semimembranosus (unipennate), gastroc (bipennate), deltoid (multipennate)
What are the 4 properties of muscles? Irritability Contractibility Extensibility Elasticity
What is irritability? The ability of a muscle to respond to stimulation; muscle is stimulated by chemical neurotransmitters
What is the only tissue more sensitive to muscle tissue? Nerve tissue
What is contractibility? Ability to shorten when sufficient stimulation is received
What is extensibility? Ability to lengthen out or stretch beyond resting length
What is extensibility determined by? Connective tissue found in perimysium, epimysium, and fascia surrounding a muscle
What is elasticity? Ability to return to resting position once stretch is removed
What is elasticity determined by? Connective tissue
What's the difference between muscle spindles and GTOs? Location
Muscle is excited by impulses from what? Alpha motor neurons
What are series elastic components? Tissues that lie in series with the active proteins (titin)
What are parallel elastic components? Noncontractile tissues in parallel with the active proteins (perymysium)
What are the 3 type of motor units? Fast fatigable (Type IIX) Fast fatigue-resistance (Type IIA) Slow (Type I)
What is the recruitment order for motor units? Type I, Type IIA, Type IIX
What is the order of recovery after exercise from slowest to fastest? Type IIX, Type IIA, Type I
If tension is generated at a slow rate, where would the injury most likely occur? Tendon-bone junction
If the tension is generated at a fast rate, where would the injury most likely occur? Within a tendon
What are the functions of muscles? Movement production Position maintenance Joint stabilization Support/protect viscera Control body entrance/exits Produce head
What is an agonist? Muscle that actively contracts to produce a desired movement (AKA: Prime mover)
What is a stabilizer? Muscle acting on a segment to allow motion at an adjacent joint to occur
What is a neutralizer? Muscle that contracts to eliminate an undesired joint action of another muscle
What is an antagonist? Muscle that acts in opposition to another
What is a synergist? Muscle that cooperates with another to produce a desired movement
According to the force-velocity curve, during a concentric contraction, as the load increases the maximal contraction velocity of a muscle does what? Decreases
According to the force-velocity curve, during an eccentric activation, speed of lengthening does what as a greater load is applied? Increases
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
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
What muscle fibers enhances power? Fast-twitch fibers
What is the stretch-shortening cycle? When a concentric contraction is preceded by an eccentric contraction (Plyometrics)
By doing a concentric contraction preceded by an eccentric contraction, what does this allow once to do? Generate greater force
How does the stretch-shortening cycle work? At the end of a pre-stretch, concentric muscle acivity is enhanced by stored elastic energy
How long is the stored energy good for before the shortening cycle? 0-.9 secs
If the stored elastic energy is lost, what happens to it? Converted to heat
What is strength? Max force or power produced by a muscle or muscle group during a maximal voluntary effort
How are strength gains commonly quantified? 1RM
What is the SAID principle? Specific adaptations to imposed demands
What does hypertrophy result from? Increased protein synthesis within muscle fibers and therefore, an increase in the physiologic cross-sectional area of the muscle
What is hyperplasia? Increase in the actual number of fibers
Where else can you see strength gains from? Nervous system more towards the beginning
How does tension build during passive stretch? As an exponential function
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
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
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)
Created by: 1185240090