What are Pimples?
Pimples are tiny skin lesions or inflammations of the skin and are commonly caused by clogged or infected pores. They usually began forming in your sebaceous hair follicles, also known as pores. Deep within these follicles are glands that secrete sebum, your skins natural oil. The problem begins with your skins renewal process of shedding old skin to make room for new cells. Sometimes these dead skin cells become sticky, clogging together to form a plug, trapping oil and bacteria inside the follicle. The trapped oil begins to form a lump as your skin continues its normal oil production. Your bodies natural defense system then sends an army of white blood cells to attack the trapped bacteria. This whole process takes around 2 to 3 weeks, resulting in a pimple.
Pimples usually develop into one of two types of lesions. Comedo - Excess oil mixed with dead skin cells under the surface form a plug, and this type appears as a whitehead or a blackhead. When the trapped sebum and bacteria stay below the skin surface, a Whitehead is formed. Whiteheads may show up as tiny white spots, or they may be so small that they are invisible to the naked eye. A blackhead is a clogged pore with a black center. A Blackhead occurs when the pore opens to the surface, and the sebum, which contains the skin pigment melanin, oxidizes and turns a brown/black color. It is not dirt and can not be washed away. Blackheads can last for a long time because the contents very slowly drain to the surface.
Papules are raised red bumps because the clogged pores have become infected with bacteria resulting in a rush of white blood cells which causes swelling and inflammation of the pore. A Pustule forms several days later when the white blood cells make their way to the skins surface. This is what people usually refer to as a "zit" or a "pimple".