表皮系统 Epidermal System 外皮系统包覆在生物体的表面，是生物体与外界环境的分界，并且保护生物体免受外来物的侵犯。 Integumentary surface coated organism, the organism is a boundary with the external environment, and to protect the organism from foreign matter violations. 以单细胞生物而言，外皮即是细胞膜及黏附在胞膜外的分泌物，然而，细菌则有细胞壁来维持细胞的形状并提供保护。 In unicellular organisms, that is, the skin cell membrane and outer membrane adhesion in the secretions, however, there are bacterial cell wall to maintain the shape of the cells and provide protection. 多细胞的无脊椎动物，其表皮大多为单层上皮细胞及黏附在胞膜外的分泌物。 Multicellular invertebrates, mostly for its skin epithelial cell monolayers and adhesion in the outer membrane secretions. 脊椎动物的外皮系统包括皮肤及皮肤衍生物。 Vertebrate skin system includes skin and skin derivatives.
外皮系统是动物最大的器官系统，除了保护的功能外，还有感觉、调节、分泌、排泄、呼吸、运动等功能。 Animal skin is the largest organ system system, in addition to protection functions, as well as feeling, regulation, secretion, excretion, respiration, movement and other functions.