Guide 02 / six systems
Muscular system
Thousands of contractile tissues create movement, maintain posture, and generate the heat that keeps the body warm.
The job
Moves the skeleton, stabilizes joints, moves substances through organs, and powers expression and breathing.
Orient yourself
Separate the muscular system into skeletal, cardiac, and smooth muscle. Skeletal muscle is the most visible layer, but the same basic idea of contraction also powers the heartbeat and the movement of material through hollow organs.
Trace a pathway
Trace a simple movement from signal to action: a motor command travels through a nerve, reaches a muscle fiber at its neuromuscular junction, and triggers a coordinated pull across a joint.
Make the connection
- Tendons attach muscle to bone, while ligaments stabilize bone to bone.
- The diaphragm changes thoracic volume, linking muscular contraction to breathing.
- Muscles need oxygen and fuel from the cardiovascular system and instructions from the nervous system.
Close the page
Can you explain it without looking?
Active recall turns recognition into understanding. Answer these prompts in your own words, then return to the guide only for the part you could not reconstruct.
What does a tendon connect?
Why do opposing muscles often work in pairs?
Which muscle changes pressure inside the thorax?