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人体是骨骼不仅支撑着全身,保护着内脏,还决定着我们的体形。骨骼由一些不同形状的骨头组成。骨头的外层坚硬,里面疏松。骨头中含有钙和磷这两种矿物质,所以十分坚硬;它还含有大量的蛋白质,因而既坚硬又柔韧。骨头的内部有空隙,里面充满了松软的骨髓。骨头的表面有很多小孔。血液通过这些小孔渗进骨髓里,把新鲜养料带给骨细胞,把废物带出骨组织,进行新陈代谢。
The body is not only supporting the bones of the body, protecting the internal organs, but also determines our body shape. Bones consist of bones of various shapes. The outer layer of bones hard, loose inside. Bones contain two minerals, calcium and phosphorus, so they are very hard; it also contains a large amount of protein, which is both hard and pliable. There are gaps inside the bones, which is full of soft bone marrow. Bone surface has many holes. Blood through these holes into the bone marrow, bring fresh nourishment to bone cells, the waste out of bone tissue for metabolism.