👉 External fluids refer to the various liquids and aqueous solutions that exist outside a biological system, such as blood, interstitial fluid, and cerebrospinal fluid. These fluids play crucial roles in maintaining homeostasis, facilitating nutrient transport, removing waste products, and providing a medium for biochemical reactions. Blood, for instance, transports oxygen, nutrients, hormones, and immune cells throughout the body while also carrying away carbon dioxide and metabolic waste. Interstitial fluid, which surrounds cells, helps in the exchange of substances between blood vessels and tissues. Cerebrospinal fluid, found in the brain and spinal cord, cushions these structures, protects them from mechanical damage, and helps regulate their chemical environment.
