Unit 3 – Introduction to Integument

Introduction to Integument

Skin, which is scientifically referred to as the integumentary system or simply integument, provides a protective outer covering over body surfaces.  Although human skin is extremely flexible and relatively lightweight it has amazing protective qualities.  Skin is our first line of defense against invasion by pathogenic microbes, damage from ultraviolet (UV) light, and injury due to mechanical trauma caused by abrasion or blunt impacts.  Although skin is not waterproof, it plays a significant role in preventing loss of water from the body.  In addition to its protective effects, skin also aids in energy (fat) storage, production of vitamin D3, plays an essential role in temperature regulation, and is packed with sensory receptors that detect external stimuli such as pressure, vibration, pain, and changes in external temperature.

Human skin is composed of several layers with various functions and the characteristics and appearance of skin varies across different regions of the body.  The chapters in this unit will focus on learning the characteristics of the three primary layers of skin (epidermis, dermis, and hypodermis) by studying skin samples from two different body regions – thin skin covering the scalp and thick skin covering the bottom of the foot (plantar skin) or the surface of the palm (palmar skin).  The primary difference between thin and thick skin is the number of layers of dead keratin-containing epidermal cells (known as keratinocytes) that stack on top of each other near the skin surface.  The chapter that covers skin of the scalp will also focus on accessory structures associated with skin such as hair, hair follicles, sebaceous (oil) glands, sweat glands, arrector pili muscles, and selected sensory receptors.