Muscle cells

Muscle cells are specialised body cells that can contract (shorten) and relax to produce movement.

• Shape and flexibility: Many muscle cells are spindle-shaped (thicker in the middle and thinner at the ends) and flexible, which helps them shorten smoothly when they contract.
• How they do their job: Inside a muscle cell are tiny protein strands (often called muscle fibres) that slide past each other, making the cell shorten—like pulling two ends of a spring closer.
• Wave-like movement in organs: In the food pipe and intestines, muscle cells contract in a coordinated wave called peristalsis, which pushes food forward even if you are upside down.
• Different kinds of muscle cells:
  • Smooth muscle (in stomach, food pipe): works automatically, usually spindle-shaped.
  • Skeletal muscle (attached to bones): helps you move your arms and legs, long and striped, under your control.
  • Cardiac muscle (heart): contracts nonstop to pump blood, strong and rhythmic.
• Why they matter: From moving your body to pushing food along and pumping blood, muscle cells turn chemical energy from food into the mechanical work that keeps you active and alive.