Muscular System
By Leonel Quintana
Definition
The muscular system is an organ system consisting of Cardiac, Smooth and Skeletal muscles. It allows movement of the body, retain posture, and circulates blood throughout the body.
Functions
The muscular system is responsible for movement of the human body. Attached to the bones are about 700 muscles that make up about half of a person's body weight. Each of these muscles is a distinct organ made of skeletal muscle tissue, blood vessels, nerves, and tendons.
Muscular Tissue Types
Skeletal Muscle
• Makes up more than 40% of a person’s body weight
• Looks striated, or banded, under the microscope
• Skeletal muscles have three parts
– Origin attached to the less movable part of the bone
– Insertion is attached to the more movable part of the bone
– The action, or body, is the thick middle part of the muscle
Smooth Muscle
• Lines various hollow organs
• Makes up the walls of blood vessels
• Found in the tubes of the digestive system
• Smooth and has no striations
• Controlled by the autonomic nervous system
Cardiac Muscle
• Found only in the heart
• Striated muscle
• Under involuntary control
• Has specialized cells that provide a stimulus for contraction