Term
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Definition
Plasma membrane
Penetrates into the cell interior to form a transverse T Tubule.
Resting sarcolemma is polarized |
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Definition
| Made up of actin molecules called G actin |
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Definition
Myosin heads are 2 small, light polypeptide chains that act as cross-bridges during contraction
Binding sites for actin thin filaments
Binding sites for ATP
ATP enzymes |
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Term
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Definition
Surrounded by a hexagonal arrangement of 6 thin filaments
Composed of myosin which is made up of a rod-like tail and 2 myosin heads(cross-bridges)
Contains 200 myosin molecules that are bundled so the tails make up the central unit and heads face outward at the opposite end |
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Definition
| Forms a chain of long filaments called F actin which is coiled into a helix structure |
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Definition
| A 3 subunit protein that binds to tropomyosin and functions in holding tropomyosin in place on the G actin strand |
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Definition
| Conduct nerve impulses to the deepest regions of the muscle cells and sarcomere. Impulses trigger the release of calcium from adjacent terminal cisternae |
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Term
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Definition
Smooth endoplasmic reticulum that surround myofibril
Terminal cisternae are large perpendicular cross-channels
Regulates intracellular calcium levels and can store or release calcium(when fiber contracts |
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Term
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Definition
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Term
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Definition
Meaning within the muscle
CT surrounding each individual muscle fiber
Is areolar CT |
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Term
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Definition
Meaning outside the muscle
Overcoar of dense irregular CT that surrounds the whole muscle |
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Term
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Definition
| Fibrous CT surrounding fascicles |
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Term
| Special Characteristics of Muscle Tissue |
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Definition
Excitability
Contractility
Extensibility
Elasticity |
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Term
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Definition
Movement of bones or fluids
Maintaining posture and body position
Stabilizing joints
Heat generation |
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Term
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Definition
| Point of muscle attachment that is moveable during contraction |
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Term
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Definition
Point of muscle that is relatively fixed during contraction.
In limb m uscles origin usually lies proximal to insertion |
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Term
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Definition
Smallest contractile unit of a muscle fiber
The region of a myofibril between 2 successive Z discs
Composed of thick and thin myofilaments |
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Term
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Definition
Long cylindrical cell with multiple muclei beneath the sarcolemma
Cytoplasm of muscle cells called sarcoplasm which contains large amounts of stored glycogen
1 muscle fiber composed of several hundred myofibrils responsible for contraction |
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Term
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Definition
Run parallel to length
Densely packed, rodlike elements 80% of cell volume
Exhibit striations: perfectly aligned repeating series of A & I bands |
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Definition
| Granules of stored glycogen provide glucose during periods of muscle cell activity |
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Definition
| A red pigment that stores oxygen |
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Definition
| Protien that connects thick filaments to thin filaments of adjacent sarcomeres |
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Definition
| Anchors thin filaments and connects each myofibril to the next |
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Term
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Definition
Made of thick filaments
Has a lighter stripe in midsection
Called H zone where no thin filaments are present
H zone becomes smaller during contraction
A band does not change size during contraction |
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Term
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Definition
Made of thin filaments which extend across the I band and partway into the A band
A dark M line bisects each H zone |
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Term
| Events at the Neuromuscular Junction |
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Definition
Nerve impulse arrives at axon terminal
ACh released and binds with receptors on the sarcolemma
Electrical events lead to the generation of an action potential |
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Term
| Events in the Generation of and Action Potential |
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Definition
Local depolarization
1. Ach binding opens chemically gated ion channels
2. Simultaneous diffusion of Na+ and K+
3. More Na+ diffuses so the interior of the sarcolemma becomes less negative
4. Local depolarization |
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Term
| Events in the Generation of an Action Potential |
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Definition
2. Generation and propagation of an action potential
End plate potential spreads to adjacent membrane areas.
Na+ channels closed and voltage-gated K channels open
Na+ influx decreases the membrane voltage toward a critical threshold
If threshold is released an action potential is generated |
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Term
| Events in the Generation of and Action Potential |
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Definition
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Term
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Definition
Does not necessarily cause shortening of the fiber
Shortening occurs when tension generated by cross bridges on the thin filaments exceeds forces opposing shortening |
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Term
| Sliding filament model of contraction |
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Definition
During contraction myosin heads bind to actin, detach, and bind again to propel the thin filaments toward the M line.
As H zones shorten and disapear sarcomeres shorten, muscle cells shorten, and the whole muscle shortens |
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Term
| Requirements for Skeletal Muscle Contraction |
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Definition
Activation
Excitation-contraction coupling |
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Term
| Events at the Neuromuscular Junction |
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Definition
Skeletal muscles are stimulated by somatic motor neurons
Each axon ending forms a neuromuscular junction with a single muscle fiber |
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Definition
| No shortening muscle tension increases but does not exceed the load |
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Definition
| Muscle shortens because muscle tension exceeds the load |
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Definition
| A motor neuron and all muscle fibers it supplies |
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Definition
| Response of a muscle to a single, brief threshold stimulus |
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Definition
Constant, slightly contracted state of all muscles
Keeps muscles healthy |
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Term
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Definition
Direct phosphorylation of ADP by creatine phosphate
Anaerobic pathway(glycolysis)
Aerobic respiration |
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Term
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Definition
| Occurs when there are Ionic imbalances and when prolonged exercise damages the SR and interferes with Ca2+ regulation and release |
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