“Bone cracking good fun!” by Lee-Anne Stafne Adults have 206 bones in their body, which decreases with age as certain bones fuse, joining two bones into a single segment. Bones provide a number of important factors for normal living: Ø they provide support for the body Ø give the body shape, form and the ability to move Ø they guard vital organs Ø they serve as levers to make movement possible Ø they are storage reservoirs for minerals and vitamins Ø bone marrow is responsible for the production of new blood cells Bones are living, changing structures that require adequate calcium and weight-bearing exercise to build and maintain their density and strength. Living bone tissue is a combination of hard organic salts (minerals) and organic compounds (collagen) Mineral storage in the bones not only ensures the structural strength and health of the bone, but also provides a reservoir of minerals, which are readily available to the body whenever needed. Microscopically, bone is a strong matrix (framework) of fibres which criss-cross in intricate patterns and are imbedded with mineral salts The most prominent mineral salt in the body is collagen (95%) a very strong and durable material. About 20% of the weight of bone is water.
Bones are classified by their physical appearance and structural make-up: Bone classifications: Physical appearance: Ø long bones Ø short bones Ø flat bones Ø specialized shapes and sizes bones Make-up of internal structure: Ø compact bone (outside surface, dense, smooth) Ø spongy bone (porus and soft, fille with bone marrow) Red and yellow bone marrow: At birth, all bone marrow is red As we age, most of it is transformed into yellow marrow by the addition of fat cells Red marrow produces: Ø red blood cells Ø platelets Ø certain white blood cells Bone marrow fills the cavities of many bones, especially long bones. By adolescence most of our marrow is yellow. In adults, red marrow is only found in: Ø long bones Ø vertebral bodies Ø sternum Ø ribs Ø bones of cranium If necessary, yellow bone marrow can make new red blood cells Red blood cells only live 120days, and are then replaced and recycled. Everyday the liver destroys about the same number of red blood cells as bone marrow creates to maintain a balance. |