Macroscopic architecture

Two types of internal bone architecture are visible to the naked eye. Cortical bone, the stronger but heavier of the two forms, comprises the outer wall of all bones and fulfils a mainly mechanical function (see insert, Figure 1). It consists of parallel cylinders of matrix (osteons) arranged along the load-bearing axis of the bone.

Within each osteon the matrix is deposited in concentric layers, each 2-3 mm thick, with a predominant fiber direction (like multilayer plywood). The central canal of each osteon contains bone cells, blood vessels and nerves.

Trabecular bone, the second architectural form, is found at the ends of long bones and in the middle of the vertebrae. It consists of a latticework of bony struts, each 100-500 mm thick. Although weaker than cortical bone, it is more cellular and hence more metabolically active.

New Mothers Guide to Breast Feeding

New Mothers Guide to Breast Feeding

For many years, scientists have been playing out the ingredients that make breast milk the perfect food for babies. They've discovered to day over 200 close compounds to fight infection, help the immune system mature, aid in digestion, and support brain growth - nature made properties that science simply cannot copy. The important long term benefits of breast feeding include reduced risk of asthma, allergies, obesity, and some forms of childhood cancer. The more that scientists continue to learn, the better breast milk looks.

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