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44 Cards in this Set

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the universal energy-carrying molecule manufactured in all living cells as a means of capturing and storing energy
thin protein filaments that, with myosin, contracts muscle fibers
A Band
These are dark bands. They are made of thick myosin filaments which overlap thin actin filaments
Concentric muscle action
Concentric training is the muscle contraction when a weight is lifted
Cross Bridge
A distinctive structure consisting of two globular heads on each myosin molecule which interact in the presence of calcium ions with specific sites on a thin actin filament. The cross-bridges contain ATPase and generate the tension developed by a muscle fibre during a muscle action
Anatomically located far from a point of reference, such as an origin or a point of attachment
eccentric muscle action
A muscle action in which a muscle exerts a force while
lengthening. Such actions are used to resist external forces, such as gravity
The connective tissue layer surrounding an individual skeletal muscle fiber
The external sheath of connective tissue surrounding a muscle
A bundle of anatomical fibers, as of muscle or nerve. Also called fascicle
H Zone
The central portion of an A band in a sarcomere; characterized by the presence of myosin filaments
I Band
The band on either side of a Z line; encompasses portions of two adjacent sarcomeres and is characterized by the presence of actin filaments
Located beneath or directed downward
The point or mode of attachment of a skeletal muscle to the bone or other body part that it moves
Isometric Muscle Action
This occurs when the tension in the crossbridge equals the resistance to shortening.
Length tension relationship
The relationship between the length of a muscle and the contractile tension that it can exert.
A muscle can usually exert its greatest contractile tension when it is at its resting length, but in normal muscle, a greater overall force is produced when the muscle is stretched, which seemingly contradicts the general length-tension relationship. However, the apparent increase is due to the contribution of the elastic components of the joint tissues and not to an increased muscle tension
M Bridge
A line in the centre of the H zone of a muscle sarcomere
Any of the threadlike fibrils that make up the contractile part of a striated muscle fiber
Motor unit
A motor neuron and the muscle fibers it innervates- all the muscle fibers of a motor unit contract together when they are stimulated by the motor neuron.
Muscle fiber
muscle cells that are:
* long sometimes the entire length of the muscle
*cylindrical 50-100 um; human hair
*have many nuclei on periphery
*straiated under low magnification
these contain the apparatus that contracts the muscle cell
*they are 1 um in diameter (1/100 diameter of human hair)
*dominate the sarcoplasm
protein filaments that make up the myofibrils of the skeletal muscle cells
*composes the major portion of the thick filament
*it includes 2 heads (cross bridges) and a tail region
neuromuscular junction
the junction between the motor neuron (nerve cell) and the muscle fibers in innervates is called both the :
motor end plate
neuromuscular junction
usually defined as its proximal (toward the center of the body) attachment
muscles fibers that align obliquely with the tendon
the connective tissue wrapping that surrounds each fascicle
a specialized connective tissure covering all bones
high tension development in the early part of the range of motion even before movement occurs when lifting weights to insure the weight is supported isometrically.
closer to the trunk
the plasma membrane of the muscle cell
myosin and actin filaments are organized longitudinally in this smallest contractile unit of skeletal muscle
reduced muscle size and strength
the cytoplasm of the muscle fiber contains:
*contractile components- which consist of protein filaments
*other proteins
*stored glycogen and fat particles
*specialized organelles such as mitochondria and the SR
sarcoplasmic reticulum
The ER of the muscle cell
*intricate system of tubules
*terminates as vesicles in the ficinity fot he z lines
sliding filament theory
*actin filaments at each end of the sarcomere slide inward on myosin filaments
*pull the z lines toward the center of the scaromere
*thus shortening the muscle fiber
*Actin filaments slide over myosin
*both the H zone and Iband shrink
*the flexion of myosin cross bridges pulling on the actin filaments causes the movement of the actin filament
***because only a super small displacemtn of the actin filament occurs with each flexion of the myosin crossbride, ver rapid, repeated flexions must occur in many crossbridges throughout the entire muscle for measureable movement to occur.
stretch shortening cylcle
It is the increase in force production
*Prestretching a muscle just prior to a concentric action can enhance force production during the contraction*
closer to the head
attaches the muscle to the bone
this is a pattern of T tubulesspaced between and perpendicular to two sarcoplasmic reticulum vesicles
protein molecule
it runs along the length of the actin filament in the grove of the double helix
a protein situated regualar intervals along the actin filament that has a high affinity for Ca 2+ ions
T tubule
Short for: transvers tubules, run perpendicular to the sarcoplasmic reticulum and terminate in the vicinity fo the Z line between tow vesicles
Z line
at both ends of the sarcomere, its where actin filaments are aligned