Integumentary system

Medical specialty: Dermatology

Surgical specialty: Plastic surgery

This is an organ system which extends over the largest volume in the body. It is the most easily visible and accessible organ system in the body. 

Functions

Thermal insulation and thermoregulation

The skin, hair, nails, and glandular secretions all provide some resistance to heat loss.
The integumentary system is able to alter its functions to adapt to changing external and internal temperatures.
Sweating is a well-known mechanism of intentional heat loss. Sweat is released from the sweat glands to coat the skin in a liquid, which removes thermal energy as it evaporates. This has a potent cooling effect.

 

Physical barrier between the internal and external enviroment

The skin, hair, nails and glandular secretions all provide some resistance to physical and chemical threats.
They also provide resistance to ionising radiation (especially ultraviolet light from the Sun).

 

Physical barrier to infection

The integumentary system, the respiratory tract and the digestive system each have large surface areas, and each is constantly exposed to the external enviroment. This is the reason why most infections involve one of these systems.

Infections more rarely affect the cardiovascular system, musculoskeletal system, and nervous system, because the infection must first pass through these external organ systems.

 

Immune system functions

Specialised cells are housed in the integumentary system to rapidly detect new threats and recruit assistance from the innate immune system and the adaptive immune system. 

 

Tools, defense against predators and rivals

The nails are useful self-repairing tools which are permanently fixed to the fingers. They are constantly growing, hard, firm, thinly edged plates of insensitive connective tissue. A large shearing force can be applied with this thin edge, to cut and tear. 

 

Metabolic functions

The skin is an ideal site for certain metabolic processes due to its large surface area and location. The skin is the tissue which is most exposed to ultraviolet light from the Sun. This energy can be harvested by skin cells and used in biosynthesis, mostly notably in vitamin D3 (cholecalciferol) synthesis.

 

Components

• The skin
• The dermal glands (sweat glands, sebaceous glands, and apocrine glands)
• The nails
• The hair

In other species

The integumentary system in other animals can include feathers, claws, horns, antlers, spines and crests.