notes.docx

NOTES FOR THE STRUCTURE OF HAIR ROOT TEST The primary function of hair is to insulate the body from the heat and the cold and to protect the head from injury and physical trauma. The secondary purpose of hair is for adornment. It has been said that our hair is our “crowning glory.” The crown represe...

NOTES FOR THE STRUCTURE OF HAIR ROOT TEST The primary function of hair is to insulate the body from the heat and the cold and to protect the head from injury and physical trauma. The secondary purpose of hair is for adornment. It has been said that our hair is our “crowning glory.” The crown represents the regal beauty and power of the tresses. The word glory symbolizes a source of pride, self-care, and esteem. As natural stylists, our most common interests are in hair growth, hair typing, hair care, and styling. Hair root—hair structure beneath the skin surface; it is the structure from which the hair grows. Hair doesn’t grow from its outer structure, the shaft, but from its inner rooted stem. 2. Hair shaft—hair structure, also known as the stem, that extends above the skin surface. This is the portion that we see and manipulate; however, it is biologically inactive. The hair follicle is the deep, angular, pocket-like depression in the scalp. Every single strand of hair is enclosed in its own follicle. It has been observed that in some cases, more than one hair can grow from a single follicle. We are born with about 100,000 to 150,000 follicles on our head. People have over 500,000 hair follicles throughout the entire body. vellus hair—short, fine “baby” hair; terminal hair—the coarser, longer hair found throughout the body. Hair follicle a deep, angular, pocket-like depression in the scalp; contains the hair root. Vellus hair short, fine, white, and downy hair, usually without a medulla. Vellus hair is found on any area of the body except the palms of hands and soles of feet. Terminal hair pigmented hair found on the scalp, arms, legs, nose, and ears. This hair is coarser than vellus hair, although it varies in texture, color, and length. Hair types fall into three very general divisions: Asian, European, and African. The round follicle generally creates straight hair and is usually seen in Asian hair types. The oval, curved, or round follicle generally creates wavy to straight hair and can be seen in European hair types. African hair types can vary from wavy/curly to coily/wiry, as well as combinations of varying degrees of highly textured hair. The hair root is protected in the dermis of the skin and is cocooned within the follicle. It is the actual stem beneath the skin. At the base of the hair root is the hair bulb. It is an enlarged, thick, round structure at the very bottom of the hair root. The bulb is essential to the health and growth of the hair shaft. The dermal papilla is made up of cells from the dermis (inner layer of the skin) directly underneath the hair follicle. It is the cone-shaped connective tissue that is designated to enclose the base or bulb of the hair follicle bulb at the base of the hair follicle. The dermal papilla is responsible for supplying the hair with oxygen-rich blood, nerves, and keratin protein cells that nourish the hair, and stimulate growth and regeneration. The papilla is active during the anagen phase, separated during the catagen phase, and totally inactive during the telogen phase of the hair growth cycle. Sebaceous Gland Sebaceous glands are sac-like structures that provide the follicle with natural oils. They are the hair’s natural conditioners. The oil glands secrete a substance called sebum, which adds luster and pliability to the hair and scalp. Sebaceous glands frequently become troublemakers by overproducing and bringing on a common form of oily dandruff. The arrector pili muscle is a small, involuntary muscle attached to the underside of a hair follicle. Fear or cold causes this muscle to contract and makes hair stand up straight, giving the skin the appearance of “goose bumps.” Eyelash and eyebrow hair does not have arrector pili muscles.