WHAT IS MUSCLE

Muscle is the contractile tissue of the body. It is derived from mesodermal layers of the body. Muscle are made up of cells. These cells consist of filaments(contractile).
Muscle cells can be classified into three groups:
1. Skeletal muscle cells
2. Cardiac muscle cells
3. Smooth muscle cells
Skeletal muscle cells are anchored by tedons to bone. They brings about skeletal movement(locomotion) and maintenance of body posture. They are about 42% of the total body mass in an average male adult and about 36% in the female.Skeletal muscle cells are arranged in a packed regular parallel bundles.
Cardiac muscle cells are found in the heart. They are arranged in a packed irregular angles bundles. The contraction of the heart is by cardiac muscle motion.
Smooth muscle cells are found in the wall of the body organs and structures like stomach, intestine, esophagus, bronchi, bladder, blood vessels, urethra, skin etc.
Generally, the main function of the muscle is to produce force that bring out movement in the organism and associated internal organs.Examples of such movements are:
(a) contraction of the heart by cardiac muscle.
(b) perislsis which pushes the food through the digestive systems(smooth muscle).
(c) movement of the eye lids(skeletal muscle).
(d) movement of the quadriceps muscle of the thigh(skeletal muscle).
The activities of the muscle accounts for much of the body's energy consumption. Muscles conserve energy in the form of adenosine triphosphate(ATP)molecules. They also keep a storage form of glucose as glycogen, which can be easily converted to glucose. This can then be converted to energy when required.
Some movement of the muscle are commanded by the nerves in response to the signal from the brain, while others are reaction to the reflective nerve stimuli.
Exercises improves muscle strength, and have many effects on the bone, connective tissues and nerves that stimulate muscles.