What are Sebaceous Glands?
While we discuss sebaceous glands frequently and how they relate to oily hair, it is good to understand what they are and how they impact the health of our hair. For the most part, these glands are necessary for providing adequate moisture to the hair follicle and contribute to flexibility, strength, shine and help guard the follicle shaft from damage.
Every once in a while these glands can "get out of control" leading to oiliness, greasiness - or, conversely, excessive dryness. Without going into a first-year college biology class, here's a synopsis of a few points that help you understand the role they play.
The human body has 14 glands or 13 glands based on the gender. The difference is with the prostate gland and the mammary glands. These glands can be divided into two categories; those with ducts and those without ducts.
Glands with ducts are also known as exocrine glands and they are made to secrete chemicals from the ducts. These glands are mammary glands, sweat glands, salivary glands, lachrymal glands, and sebaceous glands. The glands without ducts are known as Endocrine glands and they are adrenal glands, thyroid gland, pituitary glands, hypothalamus, prostate, gonads, pancreas, thymus, and pineal gland. Every gland in the body has a purpose.
Where Are The Sebaceous Glands Found
These glands are a branch of the acinar gland and are found throughout the human skin except on the palms of the hands and the soles of the feet. They are found in the largest concentrations on the scalp and face of people. With people they are found on the eyelids where they secrete sebum that is specialized to form tears. These are known as meibomian sebaceous glands.
Sebaceous glands are generally found in areas that are hair covered, as they are attached to follicles for hair. They can also be seen in some of the hairless areas on the human body such as the nose, penis, labia minora, nipples and eyelids. Here their ducts will end in sweat pores at the skinís surface.
Composition Of The Sebaceous Glands
The sebaceous glands are attached to the hair follicle to add sebum to the hair from the hair shaft. The sebum is brought to the skin surface by riding along the shaft of the hair. The entire structure is called the pilosebaceous unit and is comprised of the sebaceous gland, the arrector pili muscle, the hair follicle and the hair itself.
What Is Sebum?
Sebum is a waxy, oily substance that is secreted by the sebaceous glands and itís made of wax, fat and dead cells from fat production. Sebum is produced in specific cells within the glands before it is released as they burst.
A holocrine gland is another classification that sebaceous glands fall under. They can be responsible for skin that is greasy and the condition is generally called seborrhea. It is initially odorless but during breakdown from bacteria it can emit an odor. Sebum is also responsible for people who complain of hair that is constantly oily. In some cases this is caused by lack of washing for a few days and in other cases it is from heat and humidity. Sebum can also be found in earwax.
Why Is Sebum Important?
The primary parts composing sebum are wax esters, tryglycerides and squalene. Both squalene and wax esters are not produced elsewhere in the body. Sebum has an antimicrobial activity and has a high content of fatty acids that are water-insoluble (45%). They are important for providing Vitamin E to the surface skin, especially in the face. They are integral to protecting hair and skin from toxins as well as rain.Over productive sebaceous glands are often key contributors to acne.