The structural system consists of the skeleton (bones), muscles, skin, membranes and connective tissues. The bones provide a strong, stable, yet mobile, framework on which the muscles can act. The skeleton also supports and protects body organs, notably the brain and spinal cord (which are encased in the skull and spine) and the heart and lungs (which are protect ed by the ribs).
Structural system problems and disorders can include infections and inflammations (arthritis, gangrene, tetanus, warts, dermatitis, cold sores, ringworm, psoriasis, acne, ulcers), muscular dystrophy tumors and fibroids, cramps, fibromyalgia syndrome, and autoimmune disorders (lupus, arthritis).
EXAMINING THE STRUCTURAL SYSTEM
The skeleton plays an indispensable role in movement. In effect, it consists of a series of independent movable internal levers on which the muscles can pull to move different parts of he body. The skeleton also supports and protects body organs, as explained above. The ribs make breathing possible by supporting the chest cavity so the lungs arc not compressed, and by ping in the breathing movements
Another function of the skeleton is the production of blood cells, which are formed in bone marrow. The skeleton also acts as a reservoir for minerals, like calcium, which can be utilized when needed by other parts of the body.
Muscles are structures composed of bundles of specialized cells that contract and relax to create movement. Muscles move both the body and the organs within it. The brain controls the voluntary movement of the skeletal muscles. Muscle activity is affected by changes in chemical compos of the fluid surrounding the muscle cells. A decrease in potassium ions causes muscle weak ness, in calcium ions causes muscle spasm.
Membranes are layers of tissue, often very thin, that cover a body surface, line a cavity divide a space or organ, or form the boundaries of individual cells. We have several membranes, including the meninges, peritoneum and tympanic.
Body tissues are collections of cells specialized to perform a particular function. Connective tissues include blood, adipose tissue (fat) and various fibrous and elastic tissues (tendons, ligaments, cartilage, etc.) that hold the body together.
Skin is the body’s largest organ. It protects the internal organs from the environment. Its cells are continually being replaced as they are lost to wear and tear. The skin consists of a thin outer layer (the epidermis) and a thicker inner layer (the dermis). Beneath the dermis is the subcutaneous tissue, which contains fat. The hair and nails are extensions of the skin and are composed mainly of keratin—the main constituent of the outermost part of the epidermis. The skin acts as a barrier, shielding internal organs from injury, bacteria and harmful sunlight rays. It also regulates body temperature through perspiration.
You can help maintain structural health by getting adequate minerals in your diet, especially calcium, magnesium and phosphorus. These minerals, along with vitamin D, have been shown to help treat and prevent osteoporosis and osteomalacia (the softening and demineralizing of bones). Vitamin D is essential to the metabolism of calcium and phosphorus in the body.
Did You Know?
• The Institute of Medicine recently increased the Recommended Dietary Allowance (RDA) fir calcium. The new daily levels recommended are 1,300 mg for children 9—18 years, 1,000 mg for people 19—50 and 1,200 mg for those over 50. Old levels were 400—600 mg/day for infants up to 1 year, 800 mg/day for children 1—10, 1,200 mg/day for ages 11—24 years and 800 mg/day for adults over 24.
• Back problems are the most common physical complaints among American adults.
• It is estimated that between 30—50 million Americans have arthritis, and most adults over 50 show sonic signs of it.
• The National Research Council reports that silicon deficiency leads to structural abnormalities of the long bones and skull in chickens, leading researchers to conclude that silicon is also important to the human structural system.