3.1: Introduction

The integumentary system is made up of the skin and the subcutaneous layer that underlies it. This system makes up most of the external surface of the body. Because of its position, the integumentary system is always in direct contact with the external environment and lies between it and the internal environment of the body. Therefore, this system plays a major biological role in maintaining a person's homeostasis and thus that person's happy and healthy survival. The major functions of the integumentary system are serving as a barrier between the body and its surroundings, providing information about the external environment, regulating body temperature, starting the process of vitamin D production, and actively defending the body from harmful physical and biological factors. In addition, because it is a highly visible system, it frequently affects the social, psychological, and economic aspects of a person's life.

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