Final answer:
The integumentary system includes the skin, which has two major layers: the epidermis, the outer layer containing protective epithelial cells, and the dermis, the thicker inner layer composed of connective tissue supporting various structures like blood vessels and sweat glands.
Step-by-step explanation:
The integumentary system comprises several organs including the skin, hair, and nails, which play crucial roles in protecting the body, regulating homeostasis, and allowing sensory interaction with the external environment. Among these, the skin is the largest organ and consists of two main layers: the epidermis and the dermis.
The epidermis is the outermost layer of the skin, composed of closely packed epithelial cells. This layer is responsible for a variety of functions including the synthesis of vitamin D, protection against injury and pathogens, minimizing harmful effects of UV light exposure, and preventing water loss.
The dermis lies beneath the epidermis and is much thicker, consisting of dense, irregular connective tissue. It contains blood vessels, hair follicles, and sweat glands, among other structures that support the vitality and functionality of skin.
Underneath these two layers is the hypodermis, which is not typically included as a main layer of the skin but is associated with it, consisting mainly of loose connective and fatty tissues that provide cushioning and insulation for the body.