The integument or skin constitutes an organ system with a variety of important functions.

Consisting of dermal and epidermal layers, the skin protects the body from various kinds of mechanical injury and constitutes the first line of defense against invasion of foreign organisms. With the various epidermal appendages (hair, nails, sweat glands, and sebaceous glands, skin is critical for maintaining the body's temperature and preventing desiccation.

The skin also contains many receptors for various kinds of sensory stimuli and represents the direct site of interaction between the body and the environment. In addition, skin has various metabolic functions, such as synthesis of vitamin D by cells of epidermis.

The protective, sensory, thermoregulatory and artistic platform functions of the integument are reflected in its complex morphology.

Learning Objectives:

• Understand the functions and physiological importance of the skin.
• Know the layers of the epidermis, their cellular characteristics
• Recognize melanocytes and understand their function and mechanism of action.
• Understand the structure, function, and formation of specialized features of the integument: hair, nails, sweat and sebaceous glands.
• Know the cellular and extracellular composition of the dermis.
• Know the sensory specializations of the skin.
• Understand the basic mechanism of epidermal/dermal repair and regeneration.

The morphology of thick skin.