By: Kristen Diep & Georgeanna Octaviano

 The outer surface of bone is called the periosteum. It's a thin, dense membrane that contains nerves and blood vessels that nourish the bone.  A typical bone has an outer layer of hard or compact bone, which is very strong, dense and tough. -Within the compact bone are many layers of cancellous bone, which looks a bit like a sponge. Cancellous bone is not quite as hard as compact bone, but it is still very strong.

Inside this is a layer of spongy bone, which is like honeycomb, lighter and slightly flexible. In the middle of some bones is jelly-like bone marrow, where new cells are constantly being produced for the blood. -Calcium is an important mineral that bone cells need to stay strong so keep drinking that low-fat milk!

 A baby's body has about 300 bones at birth. These eventually grow together to form the 206 bones that adults have. Some of a baby's bones are made entirely of a special material called cartilage. Other bones in a baby are partly made of cartilage. This cartilage is soft and flexible.  During childhood, as you are growing, the cartilage grows and is slowly replaced by bone, with help from calcium.  By the time you are about 25, this process will be complete. After this happens, there can be no more growth — the bones are as big as they will ever be. All of these bones make up a skeleton that is both very strong and very light.

 Consists of the skull, vertebral column, thoracic bones, and upper & lower limb bones.  Bones provide the structure for muscles to attach so that our bodies are able to move. Tendons are tough inelastic bands that hold attach muscle to bone.  Your skeleton also helps protect your internal organs and fragile body tissues. The brain, eyes, heart, lungs and spinal cord are all protected by your skeleton. Your skull protects your brain and eyes, the ribs protect your heart and lungs and your vertebrae protect your spinal cord.  The main duty of the skeleton is to support the body. Your skeleton is strong, but very light.

 Bones are connected by joints- without them, movement would be impossible.  Muscles are also necessary for movement: They're made of tough, elastic tissue that pull our bones when we move.

 Scoliosis is a side-to- side curve of the spine. This condition becomes apparent during adolescence. It is unknown why Scoliosis affects more girls than boys. Poliomyelitis, also called polio, is a serious infection caused by a virus. A polio virus may attack the nerve cells of the brain and spinal cord, causing paralysis. Kyphosis, also called hunchback is a forward bending of the spine. It is caused by any condition that deforms the bones of the upper part of the spine so that the person is bent forward.

 Internet : - “Kids Health: Your Bones” - “Hillendale Health: Skeletal System” “Skeletal System”  Textbook: pages “Skeletal System”  Library: “Bones: Our Skeletal System” by Seymour Simon

yay.