Structure & Function

The integumentary system is the body’s outer protective covering.

It is composed of:

Skin — the main organ, consisting of:
- Epidermis: the outermost layer made mostly of keratinized stratified squamous epithelium.
- Dermis: the thicker inner layer containing connective tissue, blood vessels, nerves, glands, and hair follicles.
- (Sometimes the hypodermis or subcutaneous layer is included; it lies beneath the skin and contains fat and connective tissue.)
Accessory structures (skin appendages):
- Hair — provides protection and helps with temperature regulation.
- Nails — protect the fingertips and aid in grasping.
- Sweat glands (sudoriferous glands) — help regulate body temperature by secreting sweat.
- Sebaceous glands — produce sebum (oil) that lubricates and waterproofs the skin and hair.
Associated sensory receptors — detect touch, pressure, pain, and temperature.

The physiology of the integumentary system centers on maintaining barrier integrity, thermoregulation, sensation, immunity, metabolism, and repair.