Support Protection Movement The Skeletal System Support Protection Movement
Topics covered Structure and development Remodel and repair How bones fit together to make the skeleton How joints enable bones and muscles to work together Problems with the skeletal system
Skeletal system consists of 3 types of connective tissue Bones – the hard elements Ligaments – dense, fibrous connective tissue that binds bone to bone Cartilage – special connective tissue of fibrous & elastic collagen in a gel-like fluid called “ground substance”
Long bone
ligaments
Cartilage
Bones: The hard elements Most bone mass consists of nonliving extra cellular crystals of calcium minerals Also consists of: Living bone cells, nerves and blood vessels (bones bleed when they are cut or broken!)
5 Bone Functions Support Movement Protection Formation of blood cells Mineral storage
1. Support Bones form the structure (skeleton) to which the skeletal muscles are attached http://kidshealth.org/misc/movie/bodybasics/bodybasics_knee.html
2. Movement Bones support and interact with muscles making movement possible
3. Protection As hard elements bones surround and protect many delicate internal organs
4. Blood cell formation Certain bones contain cells that are responsible for making different types of blood cells
5. Mineral Storage Calcium, phosphates which are important to metabolic function http://www.octc.kctcs.edu/GCaplan/anat/Notes/API%20Notes%20H%20Skeletal%20System.htm
Long bones Longer than wide Cylindrical shaft called diaphysis Enlarged knobs at each end called epiphysis Compact bone forms the shaft and covers each end Central cavity of the shaft is filled with yellow bone marrow (primarily fat for energy)
Epiphysis Inside each epihysis is spongy bone that is less dense than compact bone making it light, but strong Spongy bone is a lattice work of hard relatively strong trabeculae (L. little beams) made of calcium, minerals and living cells
Long bone special function Upper arms and legs (humerous and femur) contain spaces between the trabeculae that are filled with red bone marrow. Stem cells in the red marrow are responsible for the production of red and white blood cells and platelets
Outer surface - periosteum Bones are covered by tissue called periosteum that contains specialized bone forming cells: osteocytes (Gk. Bone & cells) Osteocytes are arranged in rings in cylindrical structures called osteons (sometimes called Haversian systems)
Periosteum cont’d As bone develops and hardens osteocytes become trapped in chambers called lacunae – but stay in touch with each other via canals called canaliculi. Canaliculi are used to pass nutrients between adjacent osteocytes to nurture bone cells when far from blood vessels
Osteocytes in lacunae Waste products diffuse in the opposite direction and are removed by the blood vessels for transport to urinary system
Osteocytes in trabeculae In spongy bone osteocytes don’t need canals for nutrients and waste transportation – the trabeculae structure gives the osteocytes access to nearby blood vessels in the red marrow