Chapter 2 Your Skeletal System Objectives Identify the five main roles of the skeletal system. Describe the functions of bones and joints. Explain how you can keep your skeletal system healthy.

I ____ warm up before exercising. Quick Quiz Complete each of these statements with always, sometimes, or never. I ____ warm up before exercising. When I ride a bicycle or play contact sports, I ____ wear a helmet and other protective gear. When I ride in a vehicle, I ____ fasten my seat belt. My backpack for school is ____ less that 15% of my body weight. I ____ make an effort to eat balance meals and exercise regularly. Why do you think that teens might not always practice these healthful behaviors? Switch to QuickTake version of the quiz.

Functions of the Skeletal System Your skeletal system has five main roles. provides support protects internal organs allows your body to move stores and produces materials that your body needs

Support and Protection Your skeleton is made up of all the bones in your body. Your skeleton gives your body its basic shape and provides the support that you need. Many bones of the skeletal system protect internal organs.

Movement In coordination with your muscular and nervous systems, your skeletal system allows you to move.

Storage and Production of Materials Your bones store essential substances which are released when other parts of the body need them. Some bones also produce blood cells.

The Skeletal System Skull 1) Sternum (breastbone) 9 1) Sternum (breastbone) 10 1 2) Vertebral column (backbone) 11 12 3) Carpals 12) Ribs 2 13 4) Metacarpals 13) Radius 15 14 5) Phalanges 14) Ulna 3 4 6) Tarsals 15) Pelvic girdle 5 16 7) Metatarsals 16) Femur 8) Phalanges 17) Patella 17 18 9) Clavicle (collarbone) 18) Fibula 19 10) Scapula (shoulder blade) 19) Tibia 6 7 11) Humerus 8

Bones and Joints Your skeletal system is made up of just over 200 bones. A place in your body where two or more of your bones come together is called a joint.

Development of Bones Your bones are living structures that undergo change throughout your life. Cartilage is a tough supportive tissue that is softer and more flexible than bone. By young adulthood, most of this cartilage is replaced by bone in a process called ossification (ahs uh fih KAY shun). In a process called ossification minerals, such as calcium and phosphorus, are deposited within the cartilage, making it hard.

Structure of Bones Bone consists of two different types of tissue—compact bone and spongy bone. Another type of tissue called marrow fills the spaces in bones. There are two types of marrow—red and yellow.

Compact Bone Compact bone makes up the outer layer of all bones. Although it looks dense and solid, It is full of holes for nerves and blood vessels. Spongy Bone Spongy bone contains flat and needlelike structures that resist stress. Red bone marrow may fill the open spaces in some bones. Outer Membrane An outer membrane covers most of a long bone. The inner portion of a membrane contains cells that build up and breakdown bone. Central Cavity Central cavities in long bones usually contain yellow bone marrow (fat).

Joints Joints allow for movement and protect bones from friction and force. Bones are held together at joints by strong, fibrous bands called ligaments.

Pivot Joint A pivot joint connects your head to the first vertebra in your backbone. It allows you to turn your head from side to side. Ball-and-Socket Joint A ball-and-socket joint allows movement in all directions. Your shoulders and hips are ball-and-socket joints. Gliding Joint Gliding joints allow movement in many directions as the bones slide along each other. Your wrists and ankles contain gliding joints. Hinge Joint Hinge joints allow bending and straightening movements.Your knees and elbows are hinge joints.

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Keeping Healthy A combination of eating well, exercising, and avoiding injuries contributes to lifelong bone and joint health. Regular medical checkups can help detect skeletal system problems.

Eating Well Adequate intake of calcium and phosphorus will help your bones grow to their maximum size and strength. Osteoporosis is a condition in which the bones become weak and break easily. Other nutrients that are important for bone health include potassium, magnesium, and vitamins A, C, and D.

Exercising Another way to build strong bones and prevent osteoporosis is to get plenty of weight-bearing exercise. Activities in which the bones support the entire weight of your body help your bones grow strong and dense.

Avoiding Bone Injuries A fracture is a break in a bone. You can protect your bones from fractures. When participating in a physical activity, wear appropriate safety equipment, such as helmets and pads. Always wear a seat belt when traveling in a vehicle.

Avoiding Joint Injuries Proper warm-up and stretching exercises are important to help prevent joint injuries. Sprains A sprain is an overstretched or torn ligament. Dislocations In a dislocation, the ends of the bones in a joint are forced out of their normal positions. Torn Cartilage Serious damage to the cartilage between the bones in a joint is known as torn cartilage. Overuse Injuries When an activity is performed too often or too strenuously, joints may become irritated and inflamed.

Medical Checkups A doctor can advise you on how to prevent serious injury or recommend other professionals who can help you. A nurse or doctor may check your spine for scoliosis (skoh lee OH sis), an abnormal curvature of the spine.

Vocabulary joint A place in the body where two or more bones meet. cartilage A tough, supportive tissue that is softer and more flexible than bone. ossification The process during infancy and childhood in which cartilage is replaced by bone. marrow The soft tissue that fills spaces inside bones. ligament A strong, fibrous band that holds bones together at a joint.

Vocabulary osteoporosis A condition in which a significant loss of bone mass causes bones to become weak and break easily. fracture A break in a bone. sprain An overstretched or torn ligament. dislocation An injury that occurs when the ends of the bones in a joint are forced out of their normal positions. scoliosis An abnormal curvature of the spine.

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End of Section 11.1 Click on this slide to end this presentation.