Dilation and constriction of the blood vessels within the papillae, being so close to the skin surface, affect heat loss (dilation) or heat conservation (constriction), part of the body's temperature control mechanism. There are two major divisions of the skin, the outer epidermis and the deeper dermis. Skin observations involve colour, lesions, rashes, trauma and abnormal temperatures. Lesions of the skin are usually small, discrete, localised areas of disease. Areolar connective tissue is common in the body, not just the skin, acting as a loose packing material between other structures. Open wounds penetrate the skin to varying levels, from superficial to deep, causing many kinds of tissue damage. A large body area of superficial (first-degree) burn is far more serious than a small body area of deep (third-degree) burn. This is because in burns of large body surface area, more skin function is disrupted, particularly control of fluid loss through the skin.