Humans play a major role in the freshwater biome. For one, our brain consists of 90% freshwater. We use freshwater to regulate body temperature, transport nutrients and oxygen into cells, and moisturize the air in our lungs. Our blood consists of 83% water muscles consists of 75% water, and our bones consist of 22% water. Water is also used to help with our metabolism, protect our organs, and help our nutrients to absorb nutrients better.