The dermis lies beneath the epidermis. In addition to connective tissue, the dermis contains blood vessels and nerve cells that penetrate the subcutaneous tissue. The dermis also contains hair follicles, sweat glands, and sebaceous glands, which produce the oily substance called sebum. Sweat glands are found in almost every part of the body, especially the palms of the hands and the soles of the feet. By perspiring, the body rids itself of nitrogen-containing waste and sodium chloride, or salt.
Perspiration also helps the body eliminate excess heat.