MEPX
Chapter 4 of 14All chapters
  1. 1How the body is organised
  2. 2Cells and tissues
  3. 3The skeleton
  4. 4Muscles
  5. 5Heart and circulation
  6. 6Blood
  7. 7Lungs and breathing
  8. 8Digestion
  9. 9Kidneys and liver
  10. 10The nervous system
  11. 11The brain
  12. 12Hormones
  13. 13Skin and senses
  14. 14The immune system

Chapter 4 of 14

Muscles

Three types, one job.

Three kinds

Skeletal muscle moves the body and answers to conscious control. Smooth muscle lines the gut and vessels and works without instruction. Cardiac muscle is only in the heart and never tires.

  • Muscles pull and never push, which is why they work in opposing pairs.
  • Tendons attach muscle to bone; ligaments attach bone to bone.

How they contract

A nerve signal releases calcium inside the muscle fibre, protein filaments slide across each other, and the fibre shortens. Energy for that comes from glucose and oxygen.