Acne, a common skin condition in adolescents, is caused by an overactive sebaceous duct, particularly on the chest, back, and face. SEBACEOUS GLANDS (DERMIS): These small glands secrete SEBUM to protect the skin. The sebaceous glands secrete an oily substance that waterproofs and lubricates the skin and hair. Sometimes, the pores or follicles, as they are also called, can become blocked. The sebum (oil) drains typically to the skin's surface and becomes blocked. Bacteria begin to grow. Microcomedones are the precursors to both whiteheads as well as blackheads. Comedones are non-inflamed blemishes on the skin that can be black or whiteheads. A whitehead forms when bacteria and sebum are trapped below the skin's surface. The whiteheads can appear as small spots of the skin or be invisible. Blackheads are formed when the pores open to the surface and sebum (which contains melanin) oxidizes. It turns brown/black. This is not dirt, and it cannot be removed with water. The blackhea...