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31 Cards in this Set

  • Front
  • Back
Skeletal Muscle Fiber Arrangement
Fusiform - Biceps Brachii
Unipennate - Soleus
Bipennate - Dorsal Ineterossei
Multipennate - Quadriceps
Passive Elastic Component
Epimysium, perimysium, endomysium
-Made of collagen
Series Elastic Component
Connective tissue that is perpendicular to muscle fiber --> Tendon
Parallel Elastic Component
Surrounding Connective Tissue that is parallel to muscle fiber
Functional Unit of the Contractile Elements
Thick Myofilament
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
Myosin Head
-ATP Binding Sites
-Actin binding sites
-Hinge - where it leaves core of the thick myofilament
Thin Myofilament
-Tropomyosin - wrap around actin chain
-Troponin - at end of each tropomyosin
Regulatory Proteins of Thin Myofilaments
-Tropomyosin - inhibits myosin interaction
-Troponin - binds to tropomyosin, calcium, or inhibits actin and myosin
Function of Thin Myofilaments: Actin
-Combines with myosin head
-ATP breaks down into ADP
-Released energy causes myosin head to swivel
Function of Thin Myofilaments: Tropomyosin
-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
Function of Thin Myofilaments: Troponin
-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
Sarcoplasmic Reticulum
Stores Calcium Ions
In relaxed muscle:
-high concentration of calcium in SR
-low concentration in the sarcoplasm
Sarcotubular System
-Organized network of tubes and sacs
-Terminal Cisternae (terminal sac) - Stores calcium
-Triad - 1 t-tube and 2 terminal sacs
Excitation of Skeletal Muscle
-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
Definition of Contraction
-Active process of generating force in a muscle.
-Direction of force is exerted parallel to the muscle
Definition of Tension
-Amount of force exerted by a contracting muscle on an object
-Tension generated depends on number of cross-bridges operating at any given time
Static Contraction
-Development of tension at constant length
-Cross-bridges attach-detach-reattach with no movement of thin and thick myofilaments
Dynamic Contractions
Isotonic, Isokinetic
Isotonic - Concentric
-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
Isotonic - Eccentric
-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
-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
Functional Excursion
Lenght a muscle can shorten after it has been lengthened to its max over all possible joints
Active Insufficiency
-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
Passive Insufficiency
-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
Factors Affecting Muscle Tension
-Motor Units
-Type of Contraction
-Number of Cross-Bridges
-Speed of Contraction
Agonist or Prime Mover
Single most important force creating a particular movement
Secondary Mover or Assist
Aids prime mover when increased force is required
Muscle which has oppposite action of prime mover
Muscle which will control or neutralize undesired actions of prime mover and assist prime mover
Stabilizer or Fixator
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