The muscular system is responsible for the movement of the human body, circulation of blood throughout the body and maintaining posture. Together with the skeletal system, the muscular system forms the musculoskeletal system, which is mainly responsible for the movement of the body.
The human body has over 650 muscles that have varying roles, including movement, posture, balance, strength, heat generation, digestion and respiration. However, the three main muscles that make up the muscular system are the skeletal, smooth and cardiac muscles.
The skeletal muscle is mainly responsible for movement. Each physical function consciously performed by a person, such as speaking and walking, requires the skeletal muscle. These muscles are attached to the bones by fibers known as tendons.
The smooth muscle is an involuntary muscle found inside organs, such as the blood vessels, lymphatic vessels, uterus, urinary bladder, respiratory tract, stomach and intestines. It is referred to as the involuntary muscle, because it is controlled by the unconscious part of the brain.
The cardiac muscle is also an involuntary muscle. This muscle is found in the walls of the heart. Its role is to pump blood, oxygen and nutrients throughout the body. It also removes waste products from the cells of the body, such as carbon dioxide.