👉 The d-fluid, also known as interstitial fluid or extracellular fluid, is a crucial component of the human body's fluid system. It fills the spaces between cells (cytoplasm) and within the cavities of tissues, making up about 60% of total body water. This fluid is primarily composed of water, salts, and various dissolved substances, including glucose, amino acids, and waste products. It plays a vital role in maintaining cellular function by providing nutrients, removing waste, and facilitating the transport of substances across cell membranes. The d-fluid also helps regulate temperature and acts as a medium for biochemical reactions, making it essential for overall physiological processes.