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31 Cards in this Set
- Front
- Back
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Skeletal Muscle Fiber Arrangement
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Fusiform - Biceps Brachii
Unipennate - Soleus Bipennate - Dorsal Ineterossei Multipennate - Quadriceps |
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Passive Elastic Component
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Epimysium, perimysium, endomysium
-Made of collagen |
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Series Elastic Component
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Connective tissue that is perpendicular to muscle fiber --> Tendon
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Parallel Elastic Component
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Surrounding Connective Tissue that is parallel to muscle fiber
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Sarcomere
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Functional Unit of the Contractile Elements
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Thick Myofilament
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Light Meromyosin
-Polypeptide Chains (tail) Heavy Meromyosin -Globular end - actin binding sites and ATPase activity -Crossbridges - head - lateral projections of HMM and form Spiraling rows |
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Myosin Head
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-ATP Binding Sites
-Actin binding sites -Hinge - where it leaves core of the thick myofilament |
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Thin Myofilament
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-Actin
-Tropomyosin - wrap around actin chain -Troponin - at end of each tropomyosin |
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Regulatory Proteins of Thin Myofilaments
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-Tropomyosin - inhibits myosin interaction
-Troponin - binds to tropomyosin, calcium, or inhibits actin and myosin |
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Function of Thin Myofilaments: Actin
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-Combines with myosin head
-ATP breaks down into ADP -Released energy causes myosin head to swivel |
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Function of Thin Myofilaments: Tropomyosin
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-In relaxed muscle the myosin heads of thick myofilament lie against tropomyosin molecuses of think myofilament
-As long as myosin heads remain in contact wiht tropomyosin then nothing happens |
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Function of Thin Myofilaments: Troponin
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-Ca++ ion binding sites
-Ca++ fills site - change in shape and position of troponin -Troponin shifts, pulls tropomyosin to which it is attached -When tropomyosin is moved the myosin head now comes in contact with underlying actin molecule |
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Sarcoplasmic Reticulum
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Stores Calcium Ions
In relaxed muscle: -high concentration of calcium in SR -low concentration in the sarcoplasm |
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Sarcotubular System
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-Organized network of tubes and sacs
-T-Tubules -Terminal Cisternae (terminal sac) - Stores calcium -Triad - 1 t-tube and 2 terminal sacs |
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Excitation of Skeletal Muscle
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-Stimulus for motor nerve - Action Potential
-ACh diffuses across the NMJ -Increase membrane permeability -Muscle depolarizes -Muscle action potential -T-tube depolarizes -Release of Ca++ from terminal cisternae |
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Definition of Contraction
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-Active process of generating force in a muscle.
-Direction of force is exerted parallel to the muscle |
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Definition of Tension
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-Amount of force exerted by a contracting muscle on an object
-Tension generated depends on number of cross-bridges operating at any given time |
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Static Contraction
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-Isometric
-Development of tension at constant length -Cross-bridges attach-detach-reattach with no movement of thin and thick myofilaments |
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Dynamic Contractions
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Isotonic, Isokinetic
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Isotonic - Concentric
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-Muscle develops sufficient tension to overcome resistance and shortens
-Muscle shortens and lifts load, load remains constant throughout the shortening -Muscle length decreases during contraction -Thin and thick myofilaments slide |
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Isotonic - Eccentric
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-Muscle lengthens
-External resistance is grater than force muscle generates -Decelerate motion of joint -Muscle length is increased during contraction by applying external force -Cross-bridge is reversed |
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Isokinetic
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-Movement of joint is kept at constant velocity
-Muscle groupo contracts against a controlled accommodating resistance at a constant angular velocity -Max resistance throughout the ROM -Concentric or eccentric |
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Functional Excursion
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Lenght a muscle can shorten after it has been lengthened to its max over all possible joints
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Active Insufficiency
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-Decreased ability of 2-jt muscle to produce or maintain active tension as it reaches its shortest possible length
-Can't develop enough cross bridges |
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Passive Insufficiency
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-Decreased ability of 2-jt muscle to produce or maintain active tension as it reaches its longest possible length over 2 joints simultaneously.
-Tension produced is partly due to passive elastic component of muscle |
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Factors Affecting Muscle Tension
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-Motor Units
-Type of Contraction -Number of Cross-Bridges -Speed of Contraction |
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Agonist or Prime Mover
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Single most important force creating a particular movement
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Secondary Mover or Assist
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Aids prime mover when increased force is required
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Antagonist
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Muscle which has oppposite action of prime mover
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Synergist
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Muscle which will control or neutralize undesired actions of prime mover and assist prime mover
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Stabilizer or Fixator
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Muscle that will steady, anchor or support a bone or body part so that another muscle will pull from a firm base
-Proximal Stabilization allows distal movement |
