Bone

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The bones of a human foot
For the television series, see Bones (TV series)

Bones are parts of the human or animal skeleton of vertebrates. They are stiff organs which make up the endoskeleton. Our body is made of flesh and blood built on a framework of bones. Without our bones, we could not stand up or move about. They also protect organs inside our body.[1] The skull protects the brain and the ribs protect the heart and lungs. The jaw and cheekbones support the facial muscles, which help us smile. The number of bones in a human's neck is the same as a giraffe's.[1]

What they do[change | change source]

The bones are the framework of the body. Without them we would be a pile of skin on the floor and would not be able to move. The bones are also very important for our protection, that is, the rib cage protects the heart and lungs, cranium (skull) protects the brain, pelvis protects the reproductive organs. Bones need to be maintained by taking regular exercise and by having lots of calcium from foods like cheese, milk, and dark leafy greens such as spinach. The red bone marrow in the middle of the bigger bones is what makes the red blood cells that we need.

Osteon[change | change source]

Diagram of a typical long bone: shows compact (cortical) and cancellous (spongy) bone
Osteon
Transverse Section Of Bone.png
Diagram of compact bone from a transverse section of a long bone's cortex.
Latin Osteon
Gray's subject #18 89

Osteons are the parts of the haversian system. They are found in the bone in most mammals, and many reptiles, birds and amphibians.[2] Inside the osteons are bone cells called osteocytes, each living in its own small space. Osteocytes make contact with each other by cytoplasmic processes through a network of tiny canals. This allows the exchange of nutrients and metabolic waste. Collagen fibers in each ring of cells ('lamellae') give them structure.[3]

Osteons have a hole down the middle, called the haversian canal. This canal contains the bone's blood supply. It contains capillaries, and nerve fibres.[4]

Bone marrow[change | change source]

Inside long bones is a central core which is not there to give strength and structure. It contains the bone marrow, one of the most important tissues in the vertebrate body. It produces blood cells for the blood system, and lymphocytes for the immune system.

References[change | change source]

  1. 1.0 1.1 My First Book on the Human Body. Bath: Robert Frederick. 2004. ISBN 0-7554-3506-0.
  2. Martiniaková, Monika 2003. Differences among species in microstructure of mammalian skeleton. Dissertation, Nitra
  3. Cooper, Reginald R.; Milgram, James W.; and Robinson, Robert A. 1966 Morphology of the osteon: an electron microscopic study. Journal of Bone and Joint Surgery, 48: 1239-1271.
  4. "Haversian". The Free Dictionary. http://medical-dictionary.thefreedictionary.com/haversian. Retrieved 2016.03.10.