4.3 Functions of the Integumentary System
Learning Objectives
By the end of this section, you will be able to:
- Describe the different functions of the skin and the structures that enable them
- Explain how the skin helps maintain body temperature
The skin and accessory structures perform a variety of essential functions, such as protecting the body from invasion by microorganisms, chemicals, and other environmental factors; preventing dehydration; acting as a sensory organ; modulating body temperature and electrolyte balance; and synthesising vitamin D. The underlying hypodermis has important roles in storing fats, forming a “cushion” over underlying structures, and providing insulation from cold temperatures.
Protection
The skin protects the rest of the body from the basic elements of nature such as wind, water, and UV sunlight. It acts as a protective barrier against water loss, due to the presence of layers of keratin and glycolipids in the stratum corneum. It also is the first line of defence against abrasive activity due to contact with grit, microbes, or harmful chemicals. Sweat excreted from sweat glands deters microbes from over-colonising the skin surface by generating dermicidin, which has antibiotic properties.
Everyday Connection
Tattoos and Piercings
The word “armour” evokes several images. You might think of a Roman centurion or a medieval knight in a suit of armour. The skin, in its own way, functions as a form of armour—body armour. It provides a barrier between your vital, life-sustaining organs and the influence of outside elements that could potentially damage them.
For any form of armour, a breach in the protective barrier poses a danger. The skin can be breached when a child skins a knee, or an adult has blood drawn—one is accidental and the other medically necessary. However, you also breach this barrier when you choose to “accessorise” your skin with a tattoo or body piercing. Because the needles involved in producing body art and piercings must penetrate the skin, there are dangers associated with the practice. These include allergic reactions; skin infections; blood-borne diseases, such as tetanus, hepatitis C and hepatitis D; and the growth of scar tissue. Despite the risk, the practice of piercing the skin for decorative purposes has become increasingly popular. According to the American Academy of Dermatology, 24 percent of people from ages 18 to 50 have a tattoo.
Sensory Function
The fact that you can feel an ant crawling on your skin, allowing you to flick it off before it bites, is because the skin, and especially the hairs projecting from hair follicles in the skin, can sense changes in the environment. The hair root plexus surrounding the base of the hair follicle senses a disturbance, and then transmits the information to the central nervous system (brain and spinal cord), which can then respond by activating the skeletal muscles of your eyes to see the ant and the skeletal muscles of the body to act against th