Sebaceous Glands and Your Skin

Normal skin model on white background
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Sebaceous glands are microscopic organs in the skin that secrete an oily substance called sebum that lubricates and waterproofs the skin. The sebaceous glands are part of the integumentary system, which includes the skin, hair, nails, and other structures that help protect the body from environmental or physical damage. The glands are part of the pilosebaceous unit, which comprises the hair follicle, hair shaft, and erector pili muscles (responsible for goosebumps).

Pilosebaceous units are found everywhere on the body except the lower lip, palms of the hands, and tops and soles of the feet. The greatest concentrations, not surprisingly, are on the face, scalp, upper neck, and chest where most acne outbreaks occur.

What They Do

Depending on their location, there can be anywhere from 2,500 to 6,000 sebaceous glands per square inch. While most sebaceous glands are connected to a hair follicle, some open up directly to the surface of the skin. These include the meibomian glands of the eyelids and the Fordyce spots of the lips and genitals.

Sebaceous glands work in tandem with the sweat-producing eccrine glands to regulate body temperature. In hot conditions, the excreted sebum mixes with sweat to slow the rate of evaporation. In cold temperatures, the sebum will contain more lipids to shield the hair and skin from moisture that can facilitate heat loss.

In addition to maintaining moisture and regulating temperatures, sebum contains squalene and other substances that prevent bacteria, fungi, and other microorganisms from causing infection.

Gland Development

Sebaceous glands are first visible between weeks 13 and 16 of fetal development and emerge from the same stem cells that give rise to the outermost layer of skin, called the epidermis. Following birth, the activity of the glands will gradually decrease and become nearly inactive between the ages of two and six.

It is after this period that the production of sebum will steadily increase, reaching an apex during puberty as boys and girls both experience a sudden spike in male hormones (androgens). This overproduction, combined with the routine shedding of dead skin cells, can clog pores and lead to blackheads (open comedones), whiteheads (closed comedones), and pimples (acne).

Sebum production tends to slow by around the age of 20 and continues diminishing the older we get. As this occurs, the skin can become drier and lose elasticity. These changes, referred to sebostasis, tend to occur in tandem with decreases in androgen production.

The loss of moisture, combined with the depletion of collagen and keratin, can lead to characteristically dry skin (xerosis cutis) and brittle hair.

Role in Pimples

The condition most of us associate with the sebaceous glands is pimples. While the pores of the skin are great self-cleaning machines, any accumulation of dirt or debris can combine with sebum to create a glue-like compound that can seal the entryway.

Once blocked, bacteria like Staphylococcus aureus and Propionibacterium acnes can begin to multiply and thrive, leading to the development of a pus-filled bump we recognize as a pimple. The colonization of bacteria will further trigger an immune response, leading to inflammation as the body tries to control the infection.

Pimples are medically referred to as acne vulgaris. Those that are severe and consolidate into boil-like pustules are known as cystic acne.

Teenagers tend to be most vulnerable to pimples because the changes in hormones not only increase the volume of sebum but the concentration of wax esters within it, leading to thicker, gummier oils. Treatments include antibiotics, benzoyl peroxide, retinoids, and anti-androgen drugs such as spironolactone.

While pimples may be the result of hormonal imbalances, they can also be caused by steroids, contraceptives, and immunosuppressant drugs. Pimples can also be mistaken for other conditions such as folliculitis, lupus miliaris disseminates faciei, and Demodex mites (a microscopic, eight-legged arachnid that lives in or near follicles).

Role in Other Disorders

While pimples are the most common concern associated with the sebaceous glands, there are other conditions that can affect them as well, including:

  • Seborrheic dermatitis, a chronic, mild form of dermatitis caused by changes in the sebaceous glands
  • Nevus sebaceous, the development of a benign tumor on the skin surface (primarily the neck, face, or scalp) which can sometimes turn cancerous
  • Rosacea, a chronic inflammatory, non-infectious disease of the sebaceous glands and connective tissues of the face
  • Phymatous rosacea, a non-infectious skin condition characterized by the overgrowth of the sebaceous glands
  • Sebaceous carcinoma, a rare but aggressive form of cancer

The development of any skin condition should be seen and treated by a dermatologist.

Skin Care Tips

While genetics and hormones play a large part in the way our sebaceous glands work, there are things you can do to help them function properly:

  • Stay well hydrated. While dehydration doesn't cause acne, it can lead to the thickening of sebum as the eccrine glands are deprived of water. Generally speaking, you should drink around eight 8-ounce glasses of water every day (more if you are overweight).
  • Use a warm compress. If you have blocked pores, wash with a medicated soap and, afterward, hold a warm, moist washcloth against the skin to dissolve the sebum build-up.
  • Avoid harsh astringents or cleansers. These can cause dryness and flaking that can further potentiate pore blockage.
  • Avoid excessive sun exposure. While a little sun may help improve acne, anything more can cause dryness and inflammation. Limit your exposure to no more than 15 minutes per day, either before 11:00 a.m. or after 4:00 p.m. And always wear sunblock.
  • Moisturize. You don't need an expensive product "guaranteed" to replace lost collagen (it won't). Instead, find a non-oily lotion or cream made especially for the face. By replenishing the moisture that your sebaceous glands can't, you can slow aging-related damage and improve your overall skin quality.
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