Overview
Comprised of keratin and protein, hair is a non-living substance that comes under attack daily. The sun, wind, environmental pollutants, styling products, thermal styling tools, chemical hair treatments and neglect all serve to undermine hair’s naturally healthy condition. However, proper maintenance and care can help keep hair in a healthy state regardless of the daily factors affecting it.
Appearance
Vibrant, shiny and bouncy are all words used to describe healthy hair. Healthy hair reflects these traits because of its structure and chemical makeup. Once hair becomes damaged, it loses the ability to hold color and vibrancy. It also starts to appear dull and lifeless because of the rough, damaged texture of its outer layer.
Texture
Healthy hair has a smooth, silky texture. Fingers glide through the hair without getting snagged, tangled or caught up on rough areas. The feel of healthy hair changes very little from root to tip. Noticeable differences in texture along the hair shaft indicate damage and an unhealthy condition.
Damaged hair can be likened to a sponge. It soaks up water readily and does not want to let it go. Drying times increase as does the frustration caused by the often damp and heavy condition of the hair. Healthy hair, on the other hand, absorbs very little water. The water runs off of the hair much like water on the surface of a waxed automobile. Because water runs off or remains beaded up on the surface of the hair, healthy hair dries very quickly.
Elasticity
Undamaged hair possesses the ability to stretch and bounce back like a rubber band. Wet, healthy hair should stretch 40 to 50 percent without breaking. Damaged hair stretches very little before breaking and shows signs of stretching after the tension is released.
Structure
Healthy hair consists of two to three layers. Coarse hair possesses three layers, namely the medulla, cortex and cuticle layers. Fine hair excludes the inner, medulla layer. The cortex houses the main structure of the hair. Color, strength and texture are all determined by the contents of the cortex. Damage to the cortex undermines the strength and structure of the hair, resulting in unhealthy or damaged hair.
Composed of shingled, transparent cells, the cuticle layer protects the cortex layer from damage. In healthy hair, the cuticle layer is tightly closed. Over time, the shingled layers of the cortex become raised in response to chemical processes, thermal styling and environmental factors. In its damaged state, the cuticle layer becomes unable to protect the vital structures of the hair.
Growth
According to MedlinePlus, hair grows approximately ½ inch per month. Healthy hair grows on the head for about five years before it falls out. After shedding the hair, follicles rest for two months before growing new hair. Hair sheds at the rate of about 100 hairs per day. Because most people have anywhere from 100,000 to 120,000 hairs on their head at any given time, the loss is not noticeable. In unhealthy hair, the number of hairs shed may outnumber the number of new hairs growing in, resulting in hair loss.
