Human bones are living tissues that are quite wet within the body. The reality is that water is a fundamental component of healthy, functional bone. Bones are dynamic organs, continuously undergoing processes that rely heavily on their water content.
The Truth About Bone Hydration
Living bone is a composite material, consisting of both organic and inorganic components, with water being an integral part of its structure. The inorganic portion is primarily a mineral known as hydroxyapatite, a form of calcium phosphate, which provides rigidity and hardness. The organic matrix is largely made up of collagen, a fibrous protein that offers flexibility and resilience. Water constitutes a significant percentage of living bone.
This water exists in various forms within the bone, including both mobile and bound water. Bound water is tightly associated with the collagen fibers and mineral crystals, playing a structural role by integrating these components. Mobile water, on the other hand, fills the porous spaces within the bone tissue. This intricate integration of water with the mineral and organic matrices is what gives living bone its unique properties, allowing it to be both strong and somewhat flexible.
Water’s Crucial Role in Bone Function
Water within living bone contributes to its mechanical properties and biological processes. It plays a role in bone flexibility and shock absorption, helping the skeletal system withstand daily stresses and impacts. Specifically, bound water helps to prevent fractures by maintaining the integrity of the bone structure.
Water is essential for the transport of nutrients to bone cells and for the removal of waste products. Interstitial fluid flows through channels within the bone, delivering substances needed for cell survival and function. Proper hydration is also necessary for the production of collagen, which forms the structural scaffolding of the bone. This continuous flow and exchange facilitated by water are fundamental for bone health and the ongoing process of bone remodeling, where old bone tissue is broken down and replaced with new.
Why Bones Seem Dry Outside the Body
The common perception of bones as dry stems from observing skeletal remains, which have undergone a process called desiccation. Over time, if exposed to air, the water content within the bones evaporates. This loss of water, along with the degradation of organic materials like collagen, changes the bone’s characteristics.
Desiccated bones become much lighter, more brittle, and lose the slight flexibility present in living bone. The idiom “bone dry” itself originates from the appearance of sun-bleached animal bones that have completely lost their moisture and organic components. This visual transformation from a living, wet tissue to a dry, inert structure is why bones outside the body appear so different from their state within a living organism.