8. What part of the integumentary system helps us keep warm? a. nails b. hair c. nerves 9. This is composed of epithelial cells that serve as the outer layer of the skin. a. epidermis b. dermis c. hypodermis 10. What is the layer directly below the epidermis? a. epidermis b. dermis i c. hypodermis 11. How do you call the cells? a. melanocytes b. melanin c. keratin 12. What are the small tubular structures of the skin that produce sweat? a. sweat glands b. hair shaft c. dermis protein that is secreted by the outer layer of the epidermal