#integumentary system #anatomy and physiology #structure of skin #hair structure #sweat glands #apocrine gland #merocrine gland #epidermis #dermis #hypodermis #stratum basale #melanocyte #melanin #keratin #tactile cells #stratum spinosum #desmosome #stratum granulosum #stratum lucidum #stratum corneum #papillary layer #reticular layer #papillae #fingerprints #hair follicle #hair papilla #glassy membrane #arrector pili #goose bumps #vellus hair #terminal hair #hyponychium #eponychium