Term Definition acne Bumps on the skin that occur when the pore around a hair follicle becomes blocked, leading to inflammation or infection. apocrine glands Glands in the dermis that make and secrete sweat that contains proteins and fatty acids. autoimmune disorder A condition that arises when the body mistakes something that is safe as something harmful and mounts an immune response against it. basal layer The deepest layer of skin in the epidermis. The basal layer produces new skin cells. burn Injury to the skin caused by heat, sunlight, chemicals, or electricity. Burns are typically categorized according to three degrees of severity. collagen A fibrous substance in the dermis that gives skin strength and keeps skin hydrated. dermis Layer of skin below the epidermis. The dermis is where many of the skin’s products, blood vessels, and sensory transmissions originate. eccrine glands Glands in the dermis that make and secrete a sweat that is mostly water and salts. epidermis The most superficial of the three main layers of skin. It contains five sublayers and has no blood supply. glands Groups of cells that make and secrete a chemical substance into the body. hair follicle Structure in the dermis that produces hair. hives Red welts that develop on the surface of the skin as a result of an allergic reaction. hypodermis Deepest layer of skin, which connects the skin to muscles or bones. Also called the subcutaneous layer. keratin A protein that gives strength and durability to skin, hair, and nails. keratinized A word describing cells that have had living parts replaced by keratin. keratinocytes Cells that produce keratin. lunulaA whitish half-moon area at the base of the nail where new cell growth takes place. melanin A pigment that gives skin its color. melanocytes Cells that produce melanin. nail plate The hardened part of a finger or toenail, made of dead, keratinized cells, that we commonly think of as the nail. nail root A living part of the nail, behind the nail plate. papillae Tiny folds in a layer of epithelial tissue that serve to increase surface area. plagiarism Copying or closely imitating the exact words or the ideas of others without giving proper credit. psoriasis An