What organ and system protects by forming a selective barrier?

Skin and Integumentary system protects by forming a selective barrier.  

Explanation:

Multicellular organisms unlike unicellular organism have a variety of systems each having a different function. The body of multicellular organisms is covered with epidermis or skin which is known as  largest organ of the body. The skin consists of many sensory receptors and protects by enclosing muscles and other body tissues. While Integumentary system is made with skin and its various appendages like hair, feathers, nails etc. with receptors and secretary pores and protects the body from pain.

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