Protection and Immune Response

• The skin is the first line of defense against pathogens and toxins in the environment. When a pathogen, such as a virus or bacteria, is found by Langerhans cells, a specialized dendritic cell, the cell begins the process to destroy the pathogen and remove it from the body.
  
  

Sensation

• Skin is sensitive and causes the body to react to heat, cold, sharp pain, and pressure. Skin can provide protection from injury and can protect injured areas while healing.
  
  

Body Temperature Regulation

• Skin controls body temperature by contracting or expanding the blood vessels in the skin. Dilated blood vessels release heat from the body. Contracted blood vessels restrict heat loss. Increased perspiration cools the body while decreased perspiration keeps the body warmer.
  
  

Evaporation Control

• Skin provides a barrier to prevent fluid loss and dehydration.
  
  

Storage and Nutrient Synthesis

• Skin stores water in addition to lipids which are fat-soluble molecules such as fats, waxes, cholesterol and vitamins A, D, E and K. Interaction with UV light synthesis vitamin B and vitamin D.
  
  

Excretion

• The skin excretes urea and excess minerals. In addition, new studies show that skin excretes pheromones and may have an impact on hormonal balance of the opposite gender.
  
  

Absorption

• The skin absorbs oxygen, carbon dioxide and nitrogen in small amounts. Medicine can be formulated to be absorbed through the skin. It also absorbs many of the chemicals that are in the environment such as pollution and chemicals from body care and cleaning products.