The Skeletal System

Functions of the Skeletal System The skeleton supports the body against the pull of gravity. Thelarge bones of the lower limbs support the trunk when standing. The skeleton also protects the soft body parts. The fused bones of the cranium surround the brain to make it less vulnerable to injury. Vertebrae surround and protect the spinal cord and bones of the rib cage help protect the heart and lungs of the thorax. Bones work together with muscles as simple mechanical lever systems to produce body movement. Bones contain more calcium than any other organ. The intercellular matrix of bone contains large amounts of calcium salts, the most important being calcium phosphate.

Structure of Bone Cartilage – a connective tissue that lines the ends of bones and serves as a template for bone formation Compact bone – layer of protective hard bone tissue surrounding every bone; composed of repeating units of osteon systems Spongy bone – soft bone contains many holes and spaces surrounded by a layer of more dense compact bone Bone marrow – Red marrow produces blood cells and platelets. Yellow marrow is made of fat which stores energy Periosteum – exterior membrane which protects the bone, contains many blood vessels

Ligaments – tough band of connective tissue; connects bone to bone Tendons – thick band of connective tissue; connects bone to muscle ex. Achiles tendon connects gastrocnemius to talus bone

What is the function of Bone Marrow? Red marrow produces red blood cells, white blood cells and platelets. Yellow marrow is made of fat which stores energy

Diseases of the Skeletal System Arthritis - diseases that damages joints and their surrounding structures. The most common symptoms of arthritis include pain, some disability, and inflammation.

Osteoporosis - It is characterized by an abnormally high decrease in the amount of bone tissue in the skeleton which reduces the amount of strength that bones have. These brittle bones are far more susceptible to fracture than strong bones.

Rickets - a nutritional disorder found in children that leads to skeletal deformities due to a lack of vitamin D, calcium, and phosphorous, all of which are vital to bone development. Rickets is characterized by the improper hardening or development of bones. It often leaves children with bowed legs, swollen joints, muscle pain, a curved spine, or a swollen skull due to softened bones.