Vital functions of the skinCredit:
The skin, together with its derivatives serves several functions, mostly protective. Did you know the skin has numerous functions and ability? It can be stretched; it is waterproof and is washable. It has the ability to regenerate, able to repair cuts and heal bruises. With reasonable care, the skin is guaranteed to last for a lifetime.
Body Temperature RegulationRegulate Body TemperatureCredit:
Our internal components are always in action, providing every cell the necessary fuel for the continuity of life. Like an ordinary machine, as the body works it releases heat and we need to release that heat. For the body to function to its full capacity, the internal temperature of the body should be within the narrow range of homeostatic limits. 
During normal conditions, the amount of sweat that the sweat glands secrete is unnoticeable. When external temperatures play within then 31-32 degrees Celsius range, we secrete only up to 500ml of sweat a day. When events trigger an increase in temperature, the blood vessels found in the dermis layer of the skin dilates and it triggers the secretory action of the sweat glands. When this happens, the sweat glands vigorously secrete sweat in an effort to cool down the body. In extreme hot condition, the sweat glands can release up to 12 litres of body water a day! The release of sweat is an efficient cooling mechanism; preventing overheating as body heat dissipates. 
Conversely, the opposite happens when environmental temperatures fall. The blood vessels in the dermis layer of the skin constrict, bypassing the skin thereby allowing the temperature of the skin to level with that of the external environment. With this action, heat loss is minimal allowing the body to conserve heat. 
Cutaneous SensationHuman skin functionsCredit:
All over the body, cutaneous sensory receptors continuously supply the central nervous system of contacts happening with the body. These receptors are part of the nervous system that resides throughout the skin. To formally address these receptors, since they respond to external stimuli they are called exteroceptors. To name a few, Meissner’s corpuscles and the Merkel discs make it possible for us to feel our clothing as it touches our skin. Free nerve endings interpret harmful stimuli and alert the central nervous system to take action.
Metabolic FunctionsHuman Skin Metabolic FunctionsCredit:
Yes you read it right, the skin also has metabolic functions. Found in the blood vessels of the dermis are modified cholesterol molecules. As sunlight gets in contact with the skin, these cholesterol molecules are converted to vitamin D precursor. These vitamin D precursors are then carried by the blood vessels to different parts of the body to aid in the metabolism of calcium. An example of this is found in the digestive tract. Free calcium molecules cannot be absorbed without the presence of vitamin D.
Other metabolic functions of the skin include the conversion of topically applied cortisone into hydrocortisone, which is a potent anti-inflammatory drug; disarms and stops chemicals that may cause cancer from penetrating the epidermis. 
Blood ReservoirSpecialized skin functionsCredit:
About 5% of the blood volume of the body is found in the dermal vascular supply. What this entails is that during events when some parts of the body need more blood supply, for example a specific muscle group, the nervous system temporarily bypasses the dermal vascular supply, shunting the blood to the specific muscle group.
ExcretionFunctions of the skinCredit:
Nitrogen containing wastes, such as urea, uric acid and ammonia are ferried by the sweat outside the body. Furthermore, excessive sweating is also key in disposing excess water and salt.