What is the Sebaceous Gland and its Function?

Sebaceous Gland Function and Disorders: A Complete Skin Guide

The sebaceous gland is a type of microscopic gland which is integral to the structure and function of skin. Found in hair follicles, the gland is responsible for secreting sebum onto the skin. It provides 90% of the skin's surface lipids, ensuring that it remains hydrated and does not dry out.

There are, on average, 2,000,000 sebaceous glands in human skin; most of these glands are associated with hair follicles.

What is the sebaceous gland?

The sebaceous gland is a type of gland within the skin that releases sebum into hair follicles to keep them moisturised. These glands start to work before birth. While in the womb, the sebaceous gland generates a white, paste-like coating called vernix caseosa. This coating keeps skin moisturised until birth.

After birth, the sebaceous gland starts to produce sebum. By the time an individual reaches puberty, sebum production increases up to 500% and results in acne-prone skin.

What are the functions of sebaceous glands?

The sebaceous glands are responsible for generating and secreting sebum, an oily substance that contains fat molecules and lipids, such as glycerides, wax, squalene, cholesterol and fatty acids.

The following are some of the significant functions of the sebaceous gland:

1. Producing Sebum: Sebum acts as a lubricant for hair and skin in order to keep them soft and supple. It also creates a waterproof barrier that prevents moisture loss from the skin.
2. Androgen Metabolism: The sebaceous gland converts androgens such as testosterone into dihydrotestosterone (DHT), which stimulates the growth of body hair. Furthermore, these glands contribute to regulating hormonal activity in the skin.
3. Skin Defence: The antimicrobial properties available in sebum protect skin from infections and make the wound-healing process faster.
    

What are the Common Symptoms of Sebaceous Gland Disorders?

The most common signs of sebaceous gland disorder are lumps or bumps in the skin, tenderness or pain, infection and skin discolouration. The following are some of the common symptoms of sebaceous gland disorder:

1. Sebaceous Cysts: Sebaceous cysts, or epidermal inclusion cysts, are a type of keratin-like fluid built up under the skin. It looks similar to a bump or lump on the skin. The term "sebaceous cyst" is misleading because the sebaceous cysts are not filled with sebum.
   However, healthcare experts use this term when cysts are associated with a skin condition named steatocystoma multiplex.
2. Acne: The sebaceous gland contains all kinds of enzyme machinery that generates cytokines and hormones, a contributing factor in the pathomechanism of acne. It alters the quality of sebum lipids, increases sebum production and clogs the hair follicles, leading to acne within the follicles.
3. Sebaceous Hyperplasia: Sebaceous hyperplasia is a type of benign skin condition that is extremely common. Excessive oil in the sebaceous gland creates small yellowish bumps on the skin. These bumps occur on the forehead, nose and cheeks.
    

How Does Excessive Sebum Production Manifest on the Skin?

Production of sebum is a complex process that scientists are still researching to understand. According to research, androgens assist in regulating overall sebum production. Progesterone, it may have a minor stimulatory effect on sebum production in some circumstances, possibly through indirect mechanisms or conversion to other hormones. However, androgens like testosterone and DHT are the primary drivers of sebum production. 

What is the Effect of Excessive Sebum Production?

The effect of excessive sebum production on skin results in hyperseborrhea. It is a type of scalp problem that occurs due to hyperactivity of sebaceous glands. Initially, it causes pain and itchiness on the scalp, leading to hair loss in later stages.

What is the Difference Between Sweat and Sebum?

The effect of excessive sebum production is called hyperseborrhea. This results in visibly oily skin, particularly on the face, scalp, chest, and back. While not directly painful, hyperseborrhea can contribute to conditions like acne and seborrheic dermatitis, which may involve itchiness, scaling, and inflammation. The relationship between sebum and hair loss is complex and not solely due to oiliness. 

Here is the difference between sweat and sebum:

Since the sebaceous gland plays a crucial role in skin health, it is necessary to keep it healthy to prevent it from clogging the hair follicles. Drinking plenty of water and regularly using gentle cleansers, moisturisers, and sunscreen products could be beneficial.