Hair is the most visible sign of life on a body and can be an important part of someone’s identity. People may have a specific style or color of their hair, and it can be an indicator of their gender, worldview or socioeconomic status. It’s also a source of beauty, as well as a source of shame and guilt in certain cultures.
Each strand of hair grows from a tiny hole in the skin called a follicle. The follicle gets nutrients from an artery that runs underneath it. The follicle cells multiply, die and harden, a process called keratinization (kair-ah-tin-ZAY-shen). The cells are pushed up the follicle and out through the skin’s surface as hair. The follicle also has an oil gland, called a sebaceous gland, which produces a natural lubricant to keep the hair and follicles moisturized.
The main function of hair is to provide insulation to the head, but it can also serve to protect the skin against ultraviolet rays and other external irritants. It also helps the scalp retain heat and prevents the loss of moisture from the hair shafts. Hair in the nose and ears helps trap air to improve hearing, and hair in the eyebrows and around the eyes reduces the amount of light and dust that enters the eyes.
Some hair is colored by the presence of pigments called melanin. Two kinds of melanin are present in the hair: eumelanin (yoo-MEL-uh-nen) and pheomelanin (fee-hem-ah-LEEN). Hair color decreases with age because the melanin produced in the hair follicles is lost.
Different types of hair have different textures and sizes. The texture of hair depends on how the follicles that produce it are shaped. It can be thin, medium or thick density and either straight or curly. ‘Kinky’ hair, which is tightly coiled or wavy, falls into the medium-density category.
The condition dandruff is caused by the excessive shedding of dead skin cells from the scalp. It can be triggered by certain triggers or simply due to the body’s immune system overreacting to normal shedding. Some types of shampoos contain ingredients that help manage dandruff. These include fatty alcohols like stearyl and cetyl alcohol, which are great for detangling, and glycerine and panthenol, which add moisture to the hair and scalp. The best way to treat dandruff is to address the root cause, which can vary from person to person. It’s also common for dandruff to be aggravated by over-shampooing and by exposing the scalp to too much sun or cold. The simplest treatment for dandruff is to moisturize the scalp with special oils, such as jojoba or shea butter. In addition, a scalp massage and regular trims will help manage the condition. Lastly, a diet rich in essential fatty acids, such as omega-3s and 6, can help promote healthy hair.