BIO210Y5 Lecture Notes - Lecture 2: Arrector Pili Muscle, Hair, Sebaceous Gland
Document Summary
Hair follicles, exocrine glands, and nails are also components of the integumentary system called accessory structures. Develop from epithelial columns, cords of epidermal cells that grow into the dermis. Produce hairs that provide delicate touch sensations on general body surface. Begin thickenings of the epidermis near the tips of the fingers and toes. These thickened areas settle into the dermis and form a distinct epidermis-dermis borderline and nail field containing basal cells. Protect and support tips of fingers and toes. Hair is composed of dead, keratinized cells produced in a specialized hair follicle. We see on the surface, begins deep within the hair follicles. The portion that anchors the hair into the skin, extends from the base of hair follicle, where hair production begins, to the point where the hair shaft loses its connection with the walls of the follicle. Filled of sensory nerves surrounds the base of each hair follicle.
