#CONSTRICTOR MUSCLES SKIN#
#CONSTRICTOR MUSCLES SERIES#

The contraction and relaxation of cardiac muscle continues at a rhythmic pace until death unless the muscle is injured in some way. Unlike the involuntary muscles, which can remain in a state of contraction for long periods without tiring and are capable of sustained rhythmic contractions, the voluntary muscles are readily subject to fatigue.Ĭardiac muscles (the muscles of the heart) are the third kind they are involuntary and consist of striated fibers different from those of voluntary muscle. Groups of fibers are bundled together into fascicles, surrounded by a tough sheet of connective tissue to form a muscle group such as the biceps.

Their fibers are grouped together in sheaths of muscle cells. These are the skeletal muscles that enable the body to move, and there are more than 600 of them in the human body. Voluntary muscles are those controlled by the conscious part of the brain, and are striated. They include the countless short-fibered, or smooth, muscles of the internal organs and power the digestive tract, the pupils of the eyes, and all other involuntary mechanisms. Involuntary muscles are those not under the control of the conscious part of the brain they respond to the nerve impulses of the autonomic nervous system.

#CONSTRICTOR MUSCLES SERIES#

The last stages of swallowing and of peristalsis are actually series of contractions by the muscles in the walls of the organs involved. All or part of the walls of hollow internal organs, such as the heart, stomach, intestines, and blood vessels, are composed of muscles.

#CONSTRICTOR MUSCLES SKIN#

Others are attached to other muscles, or to skin (producing the smile, the wink, and other facial expressions, for example). Some muscles are attached to bones by tendons. At the signal of an impulse traveling down the nerve, the muscle fiber changes chemical energy into mechanical energy, and the result is muscle contraction. Muscles, especially the heart, also use free fatty acids as fuel. Each has its small stored supply of glycogen, which it uses as fuel for energy. Each fiber receives its own nerve impulses, so that fine and varied motions are possible. They also vary in shape, and in color from white to deep red. Muscle fibers range in length from a few hundred thousandths of a centimeter to several centimeters. They also protect the contents of the abdomen against injury and help support the body. Muscles are responsible for locomotion and play an important part in performing vital body functions. A bundle of long slender cells ( muscle fibers) that have the power to contract and hence to produce movement.

Constrictor muscles