1. Your Skeletal System The skeletal system has two main functions: Structure/Support and Protection Your bones also store important minerals, such as calcium and phosphorus. The human body is made up of 206 bones. You were actually born with more than 206 bones in your body. Where did they disappear to? To make your study easier, you can look at the skeleton in two parts. The Axial and the Appendicular.

3. The Axial Skeleton The axial skeleton includes the bones in your head, your breastbone, your ribs, and the bones in your backbone. Cranium-encloses the brain and protects it. Vertebrae-backbone/spinal column Consists of 26 bones. Supports the head, gives flexibility to your neck and back, and helps shield the spinal cord from injury. Cartilage-a tough, supportive tissue that is softer and more flexible than bone. Makes the backbone flexible and also absorbs shocks.

4. The Appendicular Skeleton The appendicular skeleton includes the bones in your arms, hands, legs, feet, hips, and shoulders. Joint-the point at which two bones come together. Ligaments-strong, fibrous bands hold bones together at moveable joints and prevent them from popping apart. Synovial fluid-a secretion produced by membranes around the joint which lubricates the joint and reduces wear on the bones.

5. Structure of Bones Bones are complex organs that remain active even after they stop growing. All of your bones are covered with a tough membrane called periosteum which contains cells that form new bone during growth and repair. Blood vessels run through the periosteum and branch into the bone. Compact bone-very hard and dense Spongy bone-filled with spaces and acts as a shock absorber. Marrow-soft tissue inside bones where blood is produced. There are two types: red and yellow. Most of your blood cells are manufactured in red marrow. Some bone marrow produces red blood cells and others produce white cells.

6. Development of Bone The skeleton begins development long before birth. A newborn baby’s skeleton is made mostly of cartilage. Eventually most of this cartilage is replaced by bone in the process of ossification. During this process, minerals, such as calcium and phosphorus, are deposited within the cartilage, making it hard. Ossification began before you were born and will continue until you are 20 to 25 years old. Fracture- a break in the bone. Incomplete fracture Complete fracture Open/Compound fracture

7. Incomplete Fracture A break that does not go all the way across the bone and the pieces of bone do not separate.

8. Closed/Complete Fracture Broken bone does not pierce the skin

9. Compound/Open Fracture Bone pierces the skin and germs can get inside the body and infect body tissues, including the broken bone.

10. Joint Disorders: Dislocation, Sprain, Torn cartilage, Bursitis, Arthritis Dislocation- the ends of the bones are forced out of their normal positions in a joint. Sprain- consists of overstretched or torn ligaments or tendons. Sprains occur more frequently than any other joint injury. Torn cartilage- damage to the cartilage that covers the ends of bones in a joint. Occurs most often among athletes who participate in sports that involve severe stress on the knees.

11. Joint Disorders; continued Bursitis is a painful irritation of the bursa which is a fluid-filled sac that cushions certain joints and tendons. May be caused by injury or repeated strenuous activity. Arthritis-inflammation or irritation of a joint. One of the most common non- infectious diseases, affecting nearly one in every seven people in the United States.

12. Scoliosis An abnormal curvature of the spine. In this condition, which is more common in girls than in boys, the vertebrae in the backbone line up in such a way that the backbone twists to one side. This condition can be inherited, it can also result from certain diseases, including rheumatoid arthritis and cerebral palsy. Early symptoms include shoulders that are not level, uneven hips, and an uneven waistline.

13. Osteoporosis As people become older, their bones begin to lose some of their calcium. This loss can lead to osteoporosis, a condition in which bones become weak and break easily. Elderly women are more likely to develop osteoporosis than are elderly men. Evidence indicates that regular exercise can help prevent this disorder. Your calcium intake now, during adolescence, can help you avoid osteoporosis later in life.

14. Your Muscular System How Muscles Work Types of Muscles- different kinds of muscles perform different functions. You have three types of muscles in your body: skeletal, smooth, and cardiac. Skeletal muscle is voluntary muscle, you control its movement deliberately. These muscles are attached to the bones of your skeleton and enable you to do such things as run, throw, and eat. Skeletal muscles are attached to bones by thick strands of connective tissue called tendons. Most skeletal muscles work in pairs, one muscle in the pair moves the bone in one direction, while the other moves the bone in the opposite direction.

15. Smooth and Cardiac Muscles Smooth Muscle - Works automatically to control movements inside your body, such as those involved in digestion. Smooth muscles in the walls of your esophagus and intestine push food through your digestive system. Cardiac Muscle - Found only in the heart. Like smooth muscle, it is also involuntary. Cardiac muscle contracts automatically, over and over, approximately 70 times a minute. What do you think is the strongest muscle in the body?

16. Muscle Contraction All muscles do their work by contracting, or becoming shorter and thicker. Muscle cells (fibers) contract when they are stimulated by impulses from the nervous system. Even when muscles are not moving, some of their fibers are contracting. Muscle tone is the slight, constant contraction of a muscle that is due to the contraction of some of its fibers. Muscle tone enables you to maintain your posture. (Ex. The muscles in your neck may not contract enough to move your head, but they contract enough to keep your head upright.) Muscles use energy when they contract. Sugar glucose + oxygen(carried in blood) = energy When a muscle group is highly active, oxygen cannot be supplied fast enough to the muscle fibers. Lack of oxygen forms a chemical reaction that produces a substance called lactic acid as a waste product.

17. Did you know ? l What are two main functions of the skeletal system? l The human body is made up of _____ bones. l Can you name 4 bones in the human body? l What is the supportive tissue called that is found between every joint in the body? l What is the name of the tissue that holds two bones together at a joint? l Can you name the three types of muscles in your body? l When do your bones stop growing?