The Muscular System
Start with the basics of muscle tissue and learn how three different types of muscle work together to move the body and keep it alive.
What is the muscular system?
The muscular system is made up of muscle tissue that contracts to move the skeleton, pump blood, and move materials through the digestive tract. It works closely with the skeletal and nervous systems to produce controlled movement throughout the body.
Over 600 skeletal muscles
The human body contains more than 600 skeletal muscles, arranged in anterior and posterior layers that cover the entire skeleton.
Moving the skeleton
Skeletal muscles contract to move bones at joints, letting the body walk, reach, and manipulate objects.
Holding the body upright
Muscles maintain posture by making small, continuous adjustments that keep the body balanced and upright.
Generating body heat
Muscle contraction produces heat as a byproduct, helping to maintain a stable internal body temperature.
Moving fluids and food
Cardiac and smooth muscle move blood through the heart and vessels and food through the digestive tract.
Three types of muscle tissue
The body contains three distinct types of muscle tissue, each built for a different job: skeletal muscle for voluntary movement, cardiac muscle for pumping blood, and smooth muscle for involuntary movement within organs.
Voluntary vs. involuntary control
Only skeletal muscle is under conscious, voluntary control. Cardiac and smooth muscle contract involuntarily, controlled automatically by the autonomic nervous system and by internal pacemaker cells.
Skeletal muscle is the only type you consciously control.
Skeletal muscle attaches to bone and is controlled voluntarily through the nervous system, while cardiac muscle in the heart and smooth muscle in organ walls contract automatically, without conscious effort.