The functions of the integumentary system include maintaining internal body temperature, protection, vitamin D production, detection of stimuli, and nutrient storage.
The integumentary system is made up of the skin, along with other associated structures such as hair and nails. This system performs several important functions in the body.
- It protects the body's internal organs from infection and dehydration. Tiny glands in the skin secrete oils that enhance the barrier function of the skin. Immune cells live on the skin and provide the first line of defense against infections.
- It performs an active role in maintaining the body's internal temperature through the activation of sweat glands. If the body is too hot or too cold, the brain sends nerve impulses to the skin, which has three ways to either increase or decrease heat loss from the body's surface: hairs on the skin trap more warmth if they are standing up and less if they are lying flat, glands under the skin secrete sweat onto the surface of the skin in order to increase heat loss by evaporation if the body is too hot, and capillaries near the surface can open to cool off or close when heat needs to be conserved.
- It helps the body produce vitamin D from cholesterol, through sun exposure. It stores nutrients in adipose tissue, or fat. By helping to synthesize and absorb vitamin D, the integumentary system works with the digestive system to encourage the uptake of calcium from the diet. Vitamin D enters the bloodstream through the capillary networks in the skin. Healthy functioning of the skin is also related to the digestive system because the digestion and assimilation of dietary fats and oils are essential for the body to be able to make the protective oils for the skin and hair.
- Finally, it plays a role in the detection of stimuli through touch and thermoreception. The nervous system depends on neurons embedded in the skin to sense the outside world. It processes input from the senses, including touch, and initiates actions based on those inputs. For example, when a person stubs their toe, nerve cells in the foot send signals up the leg, through the spinal cord, and up into the brain. The nerve cell connections in the brain sense these signals as pain.