Just like medical school, everything begins with anatomy. My post from 18 June 2014 began a discussion about ‘Skin Anatomy.’ Now I will add another ‘layer’ (bad skin pun), sweat glands: eccrine, apocrine and sebaceous.
The eccrine glands secrete a sweat, just a mixture of water and salt, which evaporates from the skin cooling the body. This type of sweat gland is located on most of the body. The apocrine glands secrete a mixture of water, protein, salt and lipids into hair follicles just below the hair follicles opening to through the epidermis. The apocrine glands are found primarily in the under arms, ear canals, areola and nipples, eyelids and groin. The sebaceous glands secrete sebum, a waxy or oily lubricant or waterproofing fluid. Sebaceous glands are found in the greatest numbers on the face and scalp but occur everywhere hair follicles are found.
The apocrine and especially the sebaceous glands are prone to over production of their secretions. The sebaceous glands like to over produce on the face, upper neck and jawline, and on the back and chest. This over production is often accompanied by either an irregular or increased production of skin cells which can clog the hair follicle. If the hair follicle, now packed with sebum, is closed the wall bulges becoming a whitehead. If the packed hair follicle is open to the air then the sebum, which contains dead skin cells and therefore melanin, oxidizes becoming a blackhead. If the packed hair follicle develops an overgrowth of bacteria, typically Propionibacterium acnes (abbreviated P.acnes), the whitehead can become an inflamed and painful cyst or nodule.
Certain factors get the glands all fired up, particularly hormones. Androgenic hormones, those responsible for secondary sexual characteristics, increase during puberty. These hormones are also responsible for the acne changes in women during the menstrual cycle and pregnancy, also why some oral contraceptives can improve acne. Other factors include certain medications containing corticosteroids (like prednisone, often used for severe asthma), androgens (used or abused by body builders) or lithium (for bipolar disorder). Finally some foods can trigger acne flares, dairy products and especially carbohydrate-rich, highly refined foods which increase blood sugar and insulin levels. Fortunately, greasy food and chocolate, especially dark chocolate low in added sugar, have little effect on acne.
Next: Acne, what to do about you?