Term
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Definition
Movement of the body, its parts, and materials through it.
Posture/Support.
Heat Production. |
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Term
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Definition
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Term
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Definition
Voluntary Movement
Striated (Obvious Lines)
Fibers are multi-nucleated and contract rapidly. |
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Term
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Definition
Involuntary Movement
Smooth
Fibers have a single nucleus, contract slowly and rythmically. |
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Term
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Definition
Faint striations.
Fibers have a single nucleus and contract at a variable rate.
Intercalated discs are seen between the fibers.
"Hybrid of Skeletal and Visceral"
**Looks like magnified hair under the microscope |
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Term
SARCOLEMMA
(Muscle Fiber Anatomy) |
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Definition
| Cell membrane of muscle fibers. |
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Term
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Definition
| Material inside muscle fiber. Similar to other cells' cytoplasm. |
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Term
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Definition
| Similar to endoplasmic reticulum. |
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Term
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Definition
Tiny fibers packed densley inside muscle cells.
Myofibrils = bigger cells = bigger muscles. |
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Term
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Definition
Dark Myofibril band.
Contains Myosin protein, actin, troponin.
Thick band. |
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Term
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Definition
Light Myofibril band.
Contains only actin and troponin.
Thin band. |
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Term
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Definition
Runs between I-Bands.
The distance between Z-Disks is a Sarcomere. |
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Term
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Definition
Distance between two Z-Disks. When these contract (shorten), the muscle contracts.
**Like an accordion |
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Term
MUSCLE FIBER CONTRACTION
(Sequence) |
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Definition
1) Nerve fiber endplates release ACH (acetylcholine), a neurotransmitter chemical, into the synaptic cleft.
2) ACH causes the fiber sarcolemma to become more permeable to sodium and potassium ions. Sodium DIFFUSES INTO the fiber and Potassium DIFFUSES OUT. This is known as the DEPOLARIZATION of the muscle fiber.
3) Depolarizaton triggers the SR (Sarcoplasmic Reticulum) t-tubules to release Calcium ions.
4) The calcium ions allow the thick filament crossbridges to attach to the thin filaments andpull the thin filaments in toward one another. This results in the shortening of the myofibril sarcomeres which results in the shortening (contraction) of the entire muscle fiber.
**Filaments do not change chemically. Contraction is a physical process dictated by the Sliding Filament model.** |
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Term
MUSCLE FIBER RELAXATION
(Sequence) |
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Definition
1) End place release Cholinesterase, an enzyme which breaks down ACH.
2) Repolarization of the fiber occurs. Sodium DIFFUSES OUT, Potassium DIFFUSES IN.
3) Calcium is reabsorbed into the SR T-Tubules.
4) Crossbridges release the thin filaments and they move back to the original positions. Sarcomeres lengthen, the whole fiber lengthens, and the muscle relaxes. |
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Term
MUSCULAR RESPONSES
"All Or None" Principle |
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Definition
| At any given time, a muscle cell is either 100% relaxed or completely contracted. |
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Term
MUSCULAR RESPONSES
"Recruitment of Motor Units" Principle |
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Definition
| The more motor units (numbers of muscle fibers and the nerve fibers which stimulate them) stimulated to contract within a muscle, the greater the strength of contraction of that muscle. This is what allows us to make a "weak fist" versus a "strong fist" and allows us to have fluid motions. |
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