The human body is made up of organs grouped together into systems. Body systems include the digestive system, the circulatory system, the skeletal system and the muscular system. Each system functions in synergy with the rest of your body to control functions such as movement. The muscular system consists of three main components.
Tendons
Tendons attach muscles onto bones. They are white in color, inelastic and can be straplike or cordlike in structure. Tendons transmit the force generated by your muscles into your bones so movement can occur. Tendons are avascular, which means they have a poor blood supply. This lack of blood means that tendons are slow to heal when injured. Tendons are normally named after the muscle to which they attach, for example your biceps tendon; however, some tendons have specific names such as the Achilles' tendon, which attaches your calf muscle to your heel bone. Tendons get stronger as a result of exercise but at a much slower rate than muscles.
Motor Nerves
Motor nerves control the movement of your muscles. Long wirelike structures called axons transmit electrical pulses called action potentials from your brain to groups of muscle fibers. A group of muscle fibers is known as a motor unit. When enough action potentials reach a motor unit, a contraction occurs. The number of motor units activated depends on the amount of force required. The greater the force required, the more motor units are recruited. Motor units are said to be innervated when they are working or inhibited when they are turned off.
Muscles
Muscles are red in color and have a good blood supply to keep them well oxygenated. The human body has hundreds of muscles, and each one has a name that is either Greek or Latin in origin. The name of a muscle usually reflects its location, size, appearance and/or function. For example, your biceps brachii is the two-headed muscle of your arm, whereas your rectus abdominis is your long, flat abdominal muscle.
Muscles are made up of two protein filaments called actin and myosin. The actin and myosin filaments slide past one another as a result of the action of structures called cross bridges. Each of your muscles is made up of hundreds of actin and myosin fibers, which are collectively referred to as sarcomere. A sarcomere is the smallest contractile unit within a muscle.
Functions of the Muscular System
The three components of the muscular system are primarily responsible for movement. Movement can be voluntary or involuntary. Voluntary movements include working out and walking, and involuntary movements include shivering because you are cold or flinching when you are surprised. The muscular system also aids in transporting blood up your body against gravity -- a sequence of events called the skeletal muscle pump. Muscles also provide your body with shape and protection against impact.
References
- "Principles of Anatomy & Physiology, Ninth Edition"; Sandra R. Grabowski & Gerald J. Tortora; 2000
- "Anatomy and Physiology for Dummies"; Donna Rae Siegfried; 2002
- "Strength Training Anatomy"; Frederic Delavier; 2010
