Glossary

Alopecia: Loss of hair as a result of illness, functional disorder, or hereditary disposition. The medical term for hair loss.

Alopecia Areata: A disease that causes the body to form antibodies against some hair follicles. It can result from such factors as stress, genetics and the immune system. Alopecia Areata causes sudden smooth, circular patches of hair loss.

Alopecia Totalis: A condition that results in no hair on the scalp. It may begin as Alopecia Areata or some other cause.

Alopecia Universalis: A condition that results in no hair on any part of the body, this includes eyelashes, eyebrows, and scalp hair. It may develop as alopecia areata or result from another cause.

Amino Acids: The building blocks of protein. A deficiency of amino acids may adversely affect hair growth.

Amortization: The process of converting one enzyme to another, such as testosterone to dihydrotestosterone.

Anagen: The growing phase of hair, usually lasting between one and seven years.

Catagen: The intermittent stage between the growing (anagen) and resting (telogen) phases of the hair's growth cycle.

Cortex: The layer of the hair shaft that surrounds the medulla and is filled with keratin fibers. The main structural part of the hair fiber that accounts for most of its size and strength.

Crown: The highest part of the head.

Cuticle: The outer surface of hair, composed of overlapping scales made of colorless keratin protein. It gives hair luster and shine and also provides some of its strength.

Dermal Papilla: The dermal papilla is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels, which supply glucose for energy and amino acids to make keratin. This structure is extremely important in the regulation of hair growth since it has receptors for both androgens and hair-promoting agents.

Dermis: One of the two layers of cells that form skin. Specifically, it is the innermost layer.

Dihydrotestosterone (DHT): A male hormone that is suggested to be the main cause of miniaturization of the hair follicle and of hair loss. DHT is formed when the male hormone testosterone interacts with the enzyme 5-alpha reductase.

Epidermis: The outer protective, non-vascular layer of the skin.

Female Pattern Baldness (FPB): Progressive thinning of hair throughout the entire head caused by genes, age and hormones. It usually develops at a much slower rate than male pattern baldness.

5-Alpha-Reductase: The chemical that is responsible for transforming testosterone into dihydrotestosterone.

5-Alpha-Reductase Inhibitors: Prevent the body from converting testosterone to DHT by blocking the action of the enzyme 5-alpha reductase.

Follicle: A sac-like structure just below the surface of your scalp. The sheath within which hair grows.

Follicular Unit: Natural groupings of hair that grow together as a group in the scalp and share the same blood supply.
Frontal Alopecia: Hair loss at the front of the head.

Hair Matrix: Region where hair and the structures that compose it (cortex, cuticle and medulla) are made.
Hair Shaft: Filament projecting from the epidermis that provides protection and warmth (Hair).

Hamilton Scale: Method proposed by Hamilton to rate hair loss.

Hirsutism: Excessive growth of hair of normal or abnormal distribution.

Hypertrichosis: Excessive growth of hair all over the body.

Inflammatory: Pertaining to inflammation. Inflammation is the process whereby the body reacts to injury or abnormal stimulants.

Keratin: A tough, fibrous, insoluble protein forming hair and finger nails.

Male Pattern Baldness (MPB): The most common type of hair loss that is caused by hormones, genes and age, and is usually progressive in nature. It affects the central and frontal area of the scalp and often results in a pronounced U-shape configuration.

Medulla: A central zone of cells present only in large, thick hairs.

Melanin: Pigmenting granules within the keratin fibers of the hair shaft that determine hair color. They usually decrease with age, resulting in gray or white hair.

Melanocyte: A specialized cell containing pigment (melanin), which determines hair color.

Menopause: The permanent cessation of menstruation and estrogen secretion from a woman's ovaries.

Midline: Region towards the middle of the scalp.

Miniaturization: The destructive process by which DHT shrinks hair follicles, key marker of androgenetic alopecia.

Non-scarring Alopecia: A broad category of different types of hair loss, including androgenetic alopecia. The hair follicle remains intact, thus increasing the likelihood that hair loss can be reversed.

Norwood Scale: A scale for the classification of hair loss.

Papilla: The small root area at the base of hair, which receives the nutrients from the follicle needed for hair growth.

Scarring Alopecia: Patchy hair loss with obvious sign of scalp inflammation.

Senescent Alopecia: The type of hair loss that naturally occurs with age. During the process of aging, both the duration of hair growth and the diameter of the hair follicle decrease.

Telogen: The resting phase of the hair cycle which usually lasts approximately three months.

Telogen Effluvium: The second most common form of hair loss (androgenetic alopecia is the first). A condition that causes an increased number of hairs to enter the telogen, or resting phase. The additional shedding usually occurs in response to various stresses such as emotional trauma, post-pregnancy and illness, major surgery, certain medications. Telogen effluvium can be delayed (occurring a few months after the stressful incident) or chronic (unresolved).

Telogen Loss: Loss of hair during resting phase of hair or "natural" loss.

Trichotillomania: A type of alopecia caused by the constant pulling and twirling of a specific area of scalp. The hair loss usually improves once the habit is precluded; however, in some severe cases it is permanent.