Chapter 5 Section 2 The Skeletal System Objectives

Chapter 5 Section 2 The Skeletal System Objectives • Identify the major organs of the skeletal system. • Describe four functions of bones. • Describe three types of joints. • List three injuries and two diseases that affect bones and joints. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Bones • Skeletal system – made of bones, cartilage, and the connective tissue that holds bones together • Bone Structure compact bone - bone tissue with no visible open spaces. spongy bone – provides strength and support. marrow - a soft tissue in the center of the bone. • Bone Growth Most bones start out as cartilage. Eventually, most is replaced by bone. Two exceptions are the tip of the nose and the top of the ear. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System The four functions of bones: Minerals like calcium are deposited by cells called osteoblasts. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Joints • A place where two or more bones meet is called a joint. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Joints, continued Pivot Joint Fixed Joint Saddle Joint Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Connective Tissue • Joints are held together by ligaments. (Bone to bone. ) • Muscle is attached to bone by tendons. (Muscle to bone. ) • Cartilage protects the ends of bones at a joint. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Injuries and Diseases • Bones may be fractured or broken. • Ligaments can be stretched or torn. • Osteoporosis is a disease that causes bones to become less dense. • Arthritis is a disease that causes the joints to swell or stiffen. • Tendinitis is inflammation or irritation of a tendon. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 5 Section 2 The Skeletal System Facts • An adult human skeleton has 206 bones. • Bones are covered with strong fibrous material called periosteum. • Bones are made of three types of cells: • Osteoblasts – bone producing cells • Osteocytes - bone maintaining cells • Osteoclasts – bone-destroying cells • By weight, bones are 5 times stronger than steel. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.