Muscle Types & Functions
Start with the big picture
Skeletal muscle is striated and voluntary, supporting posture, joint movement, and heat production. Cardiac muscle forms the myocardium and contracts rhythmically; its intercalated discs help coordinate cardiac fibers. Smooth muscle is non-striated and involuntary, operating in structures such as viscera and blood vessels. Despite their differences, all three types use actin–myosin cross-bridge cycling, with calcium contributing to contraction. The topic also introduces skeletal fiber classes, isotonic and isometric contractions, muscle attachments, and functional roles such as agonist and antagonist. Motor units help explain how muscle fibers are recruited for control, while muscle growth is presented chiefly as enlargement of existing fibers.
What you'll learn
- Distinguish skeletal, cardiac, and smooth muscle by structure, control, and function.
- Describe how calcium and actin–myosin cycling contribute to contraction across muscle types.
- Compare skeletal muscle fiber classes and isotonic and isometric contractions.
- Explain how attachments, functional roles, and motor units support coordinated movement.
- Identify key features of cardiac and smooth muscle organization and regulation.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
