Unit 1 Lesson 2 The Skeletal and Muscular

Unit 1 Lesson 2 The Skeletal and Muscular Systems Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What’s Inside? What are the main functions of the skeletal system? • A skeleton is a system of bones which are alive. • The skeletal system is the organ system that supports and protects the body and allows it to move. • An endoskeleton is a skeleton inside the body. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are the main functions of the skeletal system? • The skeletal system stores minerals and produces red blood cells. • Bones, like the ribcage and skull, provide protection for organs like the heart and brain. • Bones provide support for your body and make it possible to stand sit. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are the main functions of the skeletal system? • Bones provide a place for muscles to attach. The muscles pull on bone and cause movement. • Marrow is a soft tissue at the center of bones. Red marrow makes red and white blood cells. • The hard outer layer of bone, called compact bone, stores minerals such as calcium. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems No Bones About It! What are the parts of the skeletal system? • The skeletal system is divided into two parts. • The skull, vertebrae, and ribs make up the axial skeleton, which supports and protects the internal organs. • The appendicular skeleton includes the arms, legs, shoulders, and pelvis. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are the parts of the skeletal system? • Bones are alive. They have a blood supply and nerves. • A ligament is the tough, flexible strand of connective tissue that holds bones together. • Cartilage is a strong, flexible, and smooth connective tissue found at the end of bones that allows them to move smoothly. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are bones made of? • Compact bone is dense and hard, with no visible open spaces. • Spongy bone provides most of the strength and support for the bone. It has many open spaces. • Bones also contain marrow, the soft tissue in the center of bones. • Calcium, the most plentiful mineral in bones, is deposited by bone cells called osteoblasts. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are bones made of? • Connective tissue is made mostly of a protein called collagen, which allows bones to be a bit flexible. • Red marrow, at the center of flat bones, makes red and white blood cells. • Yellow marrow, at the center of long bones, stores fat. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are bones made of? • What are the functions of each of the parts of bone? v Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems How do bones grow? • Babies have cartilage that is later replaced by bone. • Growth plates are locations where long bones lengthen. • Osteocytes are bone cells that move into cartilage and harden it into bone. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems Bone Connections How are bones connected? • A joint is the place where two or more bones connect. • Fixed joints are found in the skull and allow no movement between bones. • Movable joints allow movement of the bones. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems How are bones connected? • Ball and socket joints allow one of the bones to rotate in a large circle. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems How are bones connected? • Gliding joints allow flexibility in the wrist and ankles. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems How are bones connected? • Hinge joints allow bones to move back and forth. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are some injuries and disorders of the skeletal system? • Fractures are bones that are broken. • Sprains are injuries to a ligament caused by stretching a joint too far. • Osteoporosis is a disease that causes bone to become thin and weak. • Arthritis is a disease that causes joints to stiffen, swell, and become painful. Sometimes the joint becomes misshapened. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems Keep Moving! What are the main functions of the muscular system? • The muscular system is mostly made of the muscles that allow a body to move and be flexible. • Muscle is the tissue that contracts and relaxes, making movement possible. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are three types of muscles? • The three types of muscle are skeletal, smooth, and cardiac. • Voluntary muscle is skeletal muscle that you are able to control. • Involuntary muscle is the smooth and cardiac muscle you cannot control. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are three types of muscles? • Smooth muscle is found in internal organs and blood vessels. • Cardiac muscle is the tissue that makes up the heart. • Skeletal muscle is attached to bones by tough strands of tissue called tendons. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are three types of muscles? • Most skeletal muscles work in pairs around a joint. • The flexor bends the joint. • The extensor straightens the joint. • As one muscle contracts, the other muscle relaxes. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are three types of muscles? • Point out the location of a flexor muscle and an extensor muscle. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems Move It or Lose It! What are some injuries and disorders of the muscular system? • A strain is a muscle injury in which a muscle is overstretched or torn. • Muscular dystrophy causes skeletal muscle to become weaker over time. • Tendinitis occurs when tendons become inflamed or torn. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are some benefits of exercise? • Exercise is any activity that helps improve physical fitness and health. • Exercise can increase strength, endurance, and flexibility. It can also improve heart and lung function and reduce stress. • People should get 30 to 60 minutes of exercise a day. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 1 Lesson 2 The Skeletal and Muscular Systems What are some benefits of exercise? • Resistance exercises are anaerobic exercises. Anaerobic exercises do not require oxygen for contraction, and involve short bursts of intense effort. • Endurance exercises are aerobic exercises. Aerobic exercises require oxygen for contraction, and involve extended periods of movement. • Flexibility is improved by stretching muscles. Copyright © Houghton Mifflin Harcourt Publishing Company