Sebaceous glands are located unevenly throughout the human body. If sebaceous gland production is disturbed, various problems can occur. The following is an overview of the function and structure, as well as possible complications with sebaceous glands.
What are sebaceous glands?
Oily skin can be treated with skin care creams or masks and packs. A large part of the human sebaceous glands are found on the glandular tissue of the hair. Therefore, they are also called hair follicle glands. Sebaceous glands that are not attached to hair are called free sebaceous glands and are found at the nasal opening, around eyelids and lips, and in the genital area. The Zeis and Meibom glands located around the eyelid, the Fordyce glands located in the oral mucosa, and the Tyson glands in the genital area are also included in the group of sebaceous glands. Most sebaceous glands are located on the scalp, in the genital area, and in the T-zone of the face. The only areas of the body without sebaceous glands are the soles of the feet and palms of the hands.
Anatomy and structure
Sebaceous glands are so-called holocrine glands. This means that they secrete a secretion that consists of the substance of the surrounding gland cells. Sebaceous glands are located in the dermis. They are connected to the surrounding sebaceous and hair gland follicles and are located next to them in a piston-shaped hollow. The sebum-producing glands do not have their own outlet. Their secretion, the sebum, is transported to the skin surface via the hair located on the sebaceous gland. Under the microscope, a mixture of sebum and cell parts can be seen inside the gland. There are about 40 sebaceous glands on one square centimeter of skin.
Function and tasks
Sebum consists largely of triglycerides, wax esters, fatty acids, and proteins. Sebaceous glands are located in the dermis, the second uppermost layer of skin. This layer of skin supplies nutrients to the upper layer of skin, the epidermis, which is free of blood vessels. Functioning sebum production is important for a healthy skin environment. The fatty sebum serves as protection against pathogens and damaging external influences. Sebaceous glands ensure that the upper layer of skin is supplied with sufficient moisture. They also keep the hair supple. The fatty sebum is also called sebum. It is formed inside so-called sebocytes, sebum-producing cells, and transported to the skin surface by their bursting. Sebocytes are continuously produced in the germinal layer of the sebaceous glands. Once mature, the newly formed cells move to the center of the sebaceous gland, accumulating fats (lipids) along the way. Once the sebocytes reach the center of the gland, they are bulging with lipids, so they eventually burst. The sebocyte remnants thus become part of the sebum themselves and reach the skin surface together with it. On its way to the epidermis, the sebaceous cell mixture flushes out dead and keratinized skin cells from the follicle walls. The sebum therefore also has a cleansing function. Over the course of a day, the skin surface produces about 1-2 grams of sebum. The amount of sebum secreted depends on a number of factors. Thus, not only the predisposition plays a major role. Hormone balance, gender and age, as well as nutrition and environmental influences can also affect the function of the sebaceous glands. With increasing age, sebum production decreases. Therefore, older people usually have drier and more easily vulnerable skin.
Diseases and ailments
If the production of the sebaceous glands is disturbed, the development of skin diseases is favored. A distinction is made between seborrheics, people with a relatively high sebum production, and sebostatics, with reduced sebum production. Seborrhea, an overproduction of sebum, manifests itself in a particularly oily and greasy skin appearance. If the sebum accumulates at the outlet of the sebaceous gland, it becomes clogged. This can cause the glands to swell. The result is unsightly blackheads. These usually appear distributed over the face, décolleté and back and are recognizable as small black dots. Seborrhea is often treated by administering so-called antiseborrheic agents, which bring increased sebum production back into balance. Characteristic of sebostasis, a reduced sebum production, is a dry and brittle skin appearance. The low sebum production leads to a disturbance of the skin barrier. As a result, more water is secreted from the body through the skin.The skin appears dry, sallow and greasy and the hair usually dull and lackluster. In addition, the skin can react particularly sensitively to sunlight here due to its damaged protective mantle. Itching in the affected areas is not uncommon in sebostasis. Furthermore, pathogens have easier access to the skin layer than in the case of functioning sebum production. Sebostasis is normally treated via external therapy in the form of moisturizing creams or ointments.
