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Human Body Study

Muscle Tissue

The contractile tissue — the only tissue that can actively shorten to produce force.

The four tissue types in a generalized organ wall A layered cross-section showing the four tissue types stacked as they combine to build an organ. Each label links to the article for that type: epithelial, connective, muscle and nervous tissue. basement membrane a generalized organ wall free surface Epithelial tissue Connective tissue Muscle tissue Nervous tissue The four tissue types, layered as they combine to build an organ — schematic, not to scale.

Three types

Section titled “Three types”
  • Skeletal muscle — attached to bones; striped in appearance; under voluntary control.
  • Cardiac muscle — the heart wall; striped; contracts automatically and rhythmically.
  • Smooth muscle — walls of hollow organs and vessels; not striped; works involuntarily.

How it works

Section titled “How it works”

All muscle contracts using the same molecular machinery — the proteins actin and myosin sliding past one another, powered by ATP and triggered by calcium.

What it does

Section titled “What it does”
  • Movement — of the body and of contents within it.
  • Posture and tone — sustained low-level contraction.
  • Heat — a major source of body warmth.

Key idea

Section titled “Key idea”

Three muscle types, one trick: every kind of muscle, voluntary or not, contracts by the same actin–myosin mechanism. See also the muscular system.