Bones

Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue. Bones come in a variety of shapes and have a complex internal and external structure, are lightweight yet strong and hard, and serve multiple functions. One of the types of tissue that makes up bone is the mineralized osseous tissue, also called bone tissue, that gives it rigidity and a coral-like three-dimensional internal structure. Other types of tissue found in bones include marrow, endosteum, periosteum, nerves, blood vessels and cartilage. At birth, there are over 270 bones in an infant human's body, but many of these fuse together as the child grows, leaving a total of 206 separate bones in an adult. The largest bone in the human body is the femur and the smallest bones are auditory ossicles. 
==Functions==
Bones have eleven main functions.
===Mechanical===
*Protection — bones can serve to protect internal organs, such as the skull protecting the brain or the ribs protecting the heart and lungs.
*Structure — bones provide a frame to keep the body supported.
*Movement — bones, skeletal muscles, tendons, ligaments and joints function together to generate and transfer forces so that individual body parts or the whole body can be manipulated in three-dimensional space. The interaction between bone and muscle is studied in biomechanics.
*Sound transduction — bones are important in the mechanical aspect of overshadowed hearing.
===Synthetic===
*Blood production — the marrow, located within the medullary cavity of long bones and interstices of cancellous bone, produces blood cells in a process called hematopoiesis.
===Metabolic===
*Mineral storage — bones act as reserves of minerals important for the body, most notably calcium and phosphorus.
*Growth factor storage — mineralized bone matrix stores important growth factors such as insulin-like growth factors, transforming growth factor, bone morphogenetic proteins and others.
*Fat storage — the yellow bone marrow acts as a storage reserve of fatty acids.
*Acid-base balance — bone buffers the blood against excessive pH changes by absorbing or releasing alkaline salts.
*Detoxification — bone tissues can also store heavy metals and other foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be gradually released for excretion.
*Endocrine organ — bone controls phosphate metabolism by releasing fibroblast growth factor – 23 (FGF-23), which acts on kidneys to reduce phosphate reabsorption. Bone cells also release a hormone called osteocalcin, which contributes to the regulation of blood sugar (glucose) and fat deposition. Osteocalcin increases both the insulin secretion and sensitivity, in addition to boosting the number of insulin-producing cells and reducing stores of fat.
==Trivia==
*They only make up 14 percent of your total body weight.
*Bone marrow can either be red or yellow.
*A full grown human has 206 bones in their body
*the skull is not a single bone. instead it is made of 20 smaller bones, including the jaw and teeth.
*The femur, the strongest bone in the body, is stronger than concrete.
Category:Human Body
Category:Minerals
Category:Bone
Category:Calcium