Skeletal System
Major Functions of the Skeletal System 1. Provide shape and support. 2. Enables you to move 3. Protects your organs 4. Produces blood cells 5. stores minerals and other materials until your body needs them.
Shape and Support Skeleton determines the shape of your body. The backbone or vertebral column is the center of the skeleton 26 small bones or vertebrae make up the backbone Vertebral column is flexible and able to bend.
Movement & Protection Your skeleton allows you to move Muscles attach to the bones, pulling on them to make body move. Bones protect many of the body organs Example: the skull protects the brain and the rib cage protects the heart and lungs.
Production & Storage of Substances Long bones of your arms and legs produce certain blood cells (red and white) Bones store minerals such as calcium and phosphorus and release them when the body needs them.
Bone Structure (1) Bones are complex living structures that undergo growth and development A thin tough outer membrane covers the bone Beneath the outer membrane is a layer of compact bone (hard and dense, but not solid it is filled with holes and has small canals for blood vessels nerves.
Bone Structure (2) Inside the compact bone is a layer of spongy bone. It has many small spaces, is light weight, but strong. Spongy bone is also found at ends of bones.
Bone Structure (3) In the spaces of many bones there is a soft connective tissue called Marrow Two types of Marrow: 1. Red 2. Yellow Red Marrow produces most of the body s blood cells Yellow Marrow stores fat that can serve as an energy reserve
Bone Strength Structure of bones make it both strong and light weight 20% of adults average body weight is bone Made up of minerals: Calcium & Phosphorus (similar to what is found in most rocks)
Bone Growth Bones are alive (contain cells and tissues such as blood and nerves) Bones grow in response to stress Example: when playing sports, some of your bones absorb the force of your weight. They respond by getting stronger, making new bone tissue. Example: new bone may form after an accident, when you break a bone. The new tissue forms to fill in the gap between the broken ends. Break in Femur
Bone Development As an infant, most of your skeleton is cartilage Cartilage is a strong flexible tissue. Over time the cartilage is replace by solid bone, usually complete by the time you stop growing. Not all cartilage is replaced in adults. Many joints contain cartilage, protecting the ends of bones. (ears and the end of the nose is also cartilage)
Joints A joint is a place where two bones come together. Joints allow the bones to move in different ways Two types of Joints: 1. Immovable 2. Movable Joints
Immovable Joints Allows little or no movement Example: the bones of the skull
Movable Joints Most of the joints are of this type Allow the body to move in a wide range of movements. Bones in movable joints are held together by strong connective tissue called ligaments Four types of Movable Joints: 1. Hinge 2. Ball-and-socket 3. Pivot 4. Gliding
Hinge Joint Allows forward or backward motion Example: knee, elbow
Ball-and-Socket Joint Allows the greatest range of motion Example: shoulder (the ball-and-socket joint allows you to swing your arm freely in a circle) Example: Hips
Pivot Joint Allows one bone to rotate around another. Example: Neck Allows you to turn your head from side to side.
Gliding Joint Allows one bone to slide over another Example: wrist or ankle Enable you to bend and flex as well as make limited side to side motions
Taking Care of Your Bones Healthy bones depend on a combination of: A Balanced Diet EXERCISE!! Balanced Diet: Foods high in calcium & phosphorus Dairy products Green leafy vegetables Drink lots of water Exercise: Weight bearing activities (running, lifting) help bones grow stronger and more dense.