Sebaceous Glands

Sebaceous glands secrete an oily substance called sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-producing cells. In the glands, specialized cells produce sebum and then released it as these cells burst; sebaceous glands are holocrine glands. Sebum itself is odorless, but its bacterial breakdown can produce odors. Sebum is one cause of some people experiencing "oily" hair or skin when not washed for several days. Earwax is partly composed of sebum. Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle and cracked. Sebum can also inhibit the growth of microorganisms on skin. Sebaceous glands are a branched type of acinar gland. These glands exist throughout the skin except in the palms of the hands and soles of the feet. Sebaceous glands are present in hair-covered areas, where they link to hair follicles. The glands deposit sebum on the hairs, and bring it to the skin surface along the hair shaft. The structure consisting of hair, hair follicle, arrector pili muscle and sebaceous gland is the pilosebaceous unit. Non-haired areas (glabrous skin) of the eyelids, penis, labia minora and nipples also have sebaceous. Here, the sebum traverses ducts that terminate in sweat pores on the surface of the skin. Pores range in size from 50 to 80 nanometers on average. The inner surface of the lip and the buccal surface of the cheek can potentially contain ectopic sebaceous glands commonly known as Fordyce's spots or Fordyce granules. These occur as yellowish circular dots that form clusters. Eighty percent of the population has Fordyce granules and these sebaceous glands are asymptomatic. At the rim of the eyelids, meibomian glands present as a specialized sebaceous gland. They secrete sebum into the tears coating the eye to slow evaporation.Health Insurance

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