It is the Sebaceous Gland
Sebaceous glands
The sebaceous glands are exocrine secretory organs that release what they secrete outside: sebum .
The latter, when in excess, is responsible for greasy hair, itchy hair and head , and sometimes pain in the scalp
The sebaceous gland , on the other hand, is a small sac (visually similar to a bunch of grapes), which is inserted into the hair follicle at the level of the dermis.
It is made up of glandular lobes (the grapes of the bunch), which discharge the sebum into small ducts connected to the main excretory duct (stem), which in turn travels up the skin until it reaches the surface of the scalp
It should be noted that the stem of the sebaceous gland opens at the top of the follicle, so that the sebum covers the hair before it emerges onto the scalp.
Sebaceous glands are present on almost the entire surface of the body, with the exception of the palms of the hands and the soles of the feet.
However, they are not equally distributed, given that some skin areas, including the scalp, contain a higher density.
In fact, on the scalp there are between 400 and 900 glands per square centimeter, while in most other skin areas it almost never reaches 100.
The sebaceous glands are formed at the beginning of embryonic development, immediately starting to produce their secretion.
In childhood, sebum production decreases compared to birth, and then increases again in adolescence, until reaching, around the age of 15/16, the levels of sebaceous production found in adults.
It is only with menopause, in women, and old age, in men, that sebaceous secretion decreases again.
Sebum
The content of sebaceous secretions is sebum , an acidic fatty substance with an average PH of 3.5.
Sebum is composed of a mixture of different fats that is difficult to analyze because when it reaches the scalp of the hair it mixes with cellular debris, with other fats produced by the epidermal cells and with the sweat produced by the sweat glands (head sweating).
Furthermore, sebum fats are modified by enzymes that intervene both on the skin surface and inside the excretory ducts.
Other factors also modify the composition of sebum: diet, hormones (testosterone, estrogen, cyprotene acetate, isotretinoin) and drugs.
Hormones, especially androgens, are of special importance in the production of sebum , being responsible for the development and maintenance of sebaceous secretion in both men and women.
Broadly speaking, the composition of sebum is as follows:
- free fatty acids 30%
- glycerides 29%
- wax esters 20%
- squalene 11%
- cholesterol 4%
- various 6%
Sebum has two fundamental functions:
- contributes to the formation of the hydro-lipid film which protects the skin from chemical-environmental aggression (detergents, shampoos, cosmetic applications, sun, pollution, etc.) and bacterial aggression;
- lubricates and waterproofs the growing hair shaft.
On the surface of the head the total production of sebum is 650-700 mg per day.
As it is produced, sebum is distributed on the surface of the hair not only in the terminal part of the follicles, but also subsequently, through combing and repeated contact with the hands.
If, due to dysfunctions of the sebaceous glands, the sebum produced is insufficient, the problem of dry hair and dry scalp occurs, this loses elasticity becoming dry and wrinkled, with negative consequences on the health of the hair.
The problem of greasy and oily skin, on the other hand, also called seborrheic skin as it is subject to seborrhea, is linked to the alteration of the activity of the sebaceous glands, which produce excess sebum on the scalp, giving it a shiny and unpleasant appearance.
Although hormonal dysfunctions can cause seborrhea, the majority of subjects affected do not show endocrine alterations; in these cases the seborrheic skin or even the onset of acne is explained by the hypersensitivity of the sebaceous glands .
Wanting to measure sebaceous hypersecretion, different systems can be used: friction with gauze soaked in solvent, collection of sebum on porous papers sprinkled with diethyl ether, use of sebum absorbent tape (sebutape), lipometry with photometric measurement, in addition to analysis computerized image.
Seborrhea is often accompanied by itching of the scalp and, sometimes, the formation of comedones; all phenomena often accentuated by the use of inappropriate "do-it-yourself" remedies, such as exaggerating the frequency of washing or using aggressive products that instead of eliminating excess sebum increase it.
Therefore, the use of a trichologist, to carry out an examination of the hair and possibly have an adequate trichological treatment prescribed, is necessary not only for cosmetic reasons, but also for medical reasons relating to the health of the hair and skin.
At a trichology center you could, for example, discover that sometimes a correct cleansing of the skin, using delicate products and appropriate hair lotions, is enough to return to healthy hair.
Other sebaceous gland dysfunctions
In addition to seborrhea which, as we have seen, consists in the production of excess sebum , and causes greasy scalp and greasy hair, with the possible appearance of dandruff , other alterations in the functioning of the glands and sebaceous secretion are quite common.
The most common is seborrheic dermatitis (called, by some, sebaceous dermatitis), which causes redness of the skin and flaking, as well as the formation of small yellowish scales behind the ears or near the fins of the nose.
Seborrheic dermatitis, as well as seborrhea, are often accompanied by a sensation of pain in the scalp and hair pain
It is especially common in children, but can also appear in adults, often accompanied by seborrhea.
The advice I can give you is to use suitable and specific products for this type of anomaly, don't be scared, nothing serious but it's good to take care of it because if you don't take care of it it could lead to serious problems for your hair such as loss or thinning.