- Voluntary
- Attached to bones or skin
- Very long, cylindrical, multi-nucleated cells
- Striated: packed with orderly arrangement of myofibrils
- Not self stimulating: each fiber is innervated by a branch of a somatic motor neuron as part of a motor unit
- Under control of the nervous system
- High energy requirement: Lots of mitochondria, phosphocreatine, myoglobin
- Fast contracting
- No rhythmic contractions
- Strength increases with stretching
- Fatigues easily
| - Involuntary
- Lines walls of most internal organs
- Single, tapering, mono-nucleated cells
- Not striated: Fewer myofibrils of varying lengths
- Self stimulating: not individually innervated, impulse spreads from cell to cell
- Under the control of the nervous and endocrine systems and various chemicals and stretching
- Lower energy requirement: fewer mitochondria, phosphocreatine, myoglobin
- Slower in contracting and rhythmic in some organs producing peristaltic waves along the organ
- Rhythmic contractions
- Under stress has a relaxation response
- Does not fatigue
| - Involuntary
- Found only in the heart
- Branching chains of cells connected by porous intercalated discs, with single nucleus and striations
- Striated: many myofibrils in orderly arrangement
- Self-stimulating: impulse spreads from cell to cell
- Under control of nervous and endocrine systems and various chemicals
- Intermediate energy requirement
- Intermediate speed of contraction yet contraction spreads quickly through tissue due to intercalated discs
- Rhythmic contractions
- Strength increases with stretching
- Doesn't fatigue
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