Home / Our Body Systems / The Integumentary System-Skin

The Integumentary System-Skin

Ask yourself… Yes No
Does you skin look dull and lack elasticity?    
Is it blemished or affected by acne?     
Do you suffer from hair loss?    
Do you easily get eczema or tinea?    
Do you suffer from itching hands or athlete's foot?    
Do you suffer from endocrine problems?    
Are you often exposed to the sun?    
Do you frequently suffer from allergies or food poisoning?    
Do you always go to bed late?    


The skin is the body's largest organ.  It occupies more than 20 square feet of space and weights a full 10 pounds.  The skin is our first barrier against the millions of potentially harmful substances the body is exposed to daily.  Without its tough system of layers, the body's life-sustaining organs and systems would be exposed to an unstoppable barrage of pathogens.  Without the skin, the immune system would be easily outnumbered and overwhelmed.

The skin is composed of many layers to provide a series of obstacles to potential invaders. 

The top layer is called the epidermis.  It covers a thicker layer called the dermis, which house hair follicles, blood vessels, sweat glands and sebaceous glands.  The skin offers both active and passive aid to the immune system.  Keeping out potentially harmful microbes by secreting lysosomes and other chemicals is just one of the skin's active defenses.

The skin's passive defense is its constant process of regeneration where bacteria are discarded together with dead skin cells.  Though usually invisible to the naked eye, this process is one of the most important activities of the skin.  Every time we scrub our skin or even brush it against another surface, we aid the process of regeneration.    

The skin is also a defender in other ways.  Its melanin pigment protects us against the sun's damaging rays.  The thick dermal layer combines with underlying fat cells to act as a shock-absorbent cushion against external physical contact, further protecting the rest of the body for example, when we fall or are hit by another object.

This system also notifies the immune system of the type of invaders that escape its defenses.  The skin's Langerhans cells reveal the identity of foreign substances entering the body through the skin.  On receiving this information, the immune system is able to launch an appropriate counter-offensive against the invaders.