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Muscle Physiology 2


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Alignment of myosin or thick myofilaments(6)
Thin Myofilaments
Action Potential
Electrical Nerve Impulse(7)
Concentric Muscle Action
Resistance is less than muscle force.(8)
Globular heads that protrude away from the myosin filament at regular intervals.
Farther from the trunk(4)
Fibrous connective tissue that covers the skeletal muscles(4)
A tough, inelastic tissue that connects muscle to bone(4)
A specialized connective tissue covering all bones
closer to the trunk
closer to the head
closer to the feet
Orgin of a muscle
its proximal attachment
insertion of a muscle
its distal attachment(4)
Muscle Fibers
Muscle Cells(4)
A bundle of muscle fibers(4)
Connective tissue that surrounds the Fasciculi
Connective tissue that surrounds each muscle fiber.
A muscle fiber's membrane that encircles and is continuous with the endomysium
Neuromuscular Junction
motor end plate(5)
Motor Unit
A motor neuron and the muscle fibers it innervates
Cytoplasms of the muscle fiber that contains contractile components like protein filaments, stored glycogen and fat particles, enzymes, and specialized organelles like mitochondria and sarcoplasmic reticulum
Any of the threadlike fibrils that make up the contractile part of a striated muscle fiber
Thick Myofilaments
Globular heads that protrude away from the myosin filament at regular intervals.
The smallest contractile unit of skeletal muscle. Contains the Myosin and Actin filaments.
Where myosin filaments anchor to each other in the center of the sarcomere.
The center of the sarcomere where only myosin are only found.
The end of the sarcomere where the actin filaments are anchored.
An area of the sarcomere where only actin filaments are found.
Sarcoplasmic Reticulum
System of tubules that store Calcium ions.
Transverse Tubules
(T-tubules) Run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity of the Z-line. They carry the action-potential throughout the muscle fiber.
The pattern of a T-tubule spaced between and perpendicular to two sarcoplasmic reticulum vesicles.
Sliding-Filament Theory
States that the actin filaments at each end of the sarcomere slide inward on myosin fliaments.

5 Phases:
Resting Phase of the Sliding-Filament Theory
No tension is developed in the muscle.
Excitation-Contraction Phase of the Sliding Filament Theory
Sacroplasmic Reticulums releases Calcium that binds with troponin, found on the actin filament, which causes a shift to occur in the tropomyosin, also found on the actin filament, which allows cross-bridge flexion to occur.
Contraction Phase of the Sliding-Filament Theory
ADP connects to the cross-bridge causing the the cross-bridge to flex and the actin to slide toward the center of the sarcomere. ATP releases the cross-bridge and causes the actin to slide away from the center of the sacromere.
Recharge Phase of the Sliding-Filament Theory
So long as Calcium, ATP for the uncoupling of the myosin from the actin, and sufficient active myosin ATPase is available for catalyzing the breakdown of ATP will the muscle continue to shorten.
Relaxation Phase
Occurs when the stimulation of the motor nerve stops. Calcium is pumped back into the sarcoplasmic reticulum, which prevents the link between the actin and myosin filaments.
Type I muscle
Slow Twitch that resist fatique by having a large number of mitochondria and dense capillary concentration
Type IIa
Fast-twitch oxidative glycolytic, muscle fiber has more mitochondria, greater aerobic enzyme activity, and greater capillary density than Type IIb muscle fibers.
Type IIb
Fast glycolytic, muscle fiber fatigues rapidly and has relatively few mitochondria, low aerobic enzyme activity, and few capillaries.
Isometric muscle actions
Resistance is equal to muscle force.
Eccentric muscle action
Resistance is greater than muscle force.
Gauge of Force Production
The number of myosin cross-bridges that are attached to actin filaments at any instance in time dictates how much force is being produced in that muscle.
Motor Unit Recruitment
(Force Production)
Force production is controlled in two main ways:
1)Frequency of stimulation of motor units
2)The number of motor units activated.
(Force Production)
It takes time for all the potential myosin cross-bridge heads to make contact with actin filaments. High tension is developed in a muscle even before movement occurs when lifting weights because the weight must be supported isometrically.
Cross-Sectional Area relating to Force Production
Thicker muscles have greater potential for generating force.
Velocity of Shortening relating to Force Production
The longer the muscle the increase in velocity of shortening. (2 sarcomeres in series can shorten in the same time that 1 sarcomere can but move 2 times as far.)
Force Production related to speed of concentric actions
Less force production is possible during faster movements. More force is possible during slower movements.
Force Production related to speed of eccentric actions
As the velocity of eccentric actions increases, maximal force production also increases.
Angle of Pennation relating to force production
The greater the angle from parallel to the tendon the more sarcomeres in parallel and the fewer in series and so the muscles are able to generate more force but they will have a lower maximal shortening velocity.
Pennate muscle
Has muscle fibers that align obliquely with the tendon.
Length-Tension Relationship
Peak force production is at resting length or slightly greater than resting length. Shorter or longer negatively affects its ability to produce force.
Stretch-shortening cycle
Prestretching a muscle just prior to a concentric action can enhance force production during the subsequent contraction.
Delayed-onset muscle soreness
1) Normally occurs 24 to 72 hours after exercise
2)Eccentric muscles induce the most DOMS.
3)Normally associated with strength loss
4)Probably happens from an inflammation -induced increase in fluid in the muscle.
Reduced muscle size and strength.

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