Ch. 6: Skeletal System – Bones and Bone Structure

Introduction

The skeletal system is a fundamental organ system in human anatomy and physiology, providing the framework for the body, supporting movement, and protecting vital organs. This chapter introduces the major components and functions of the skeletal system, as well as the classification and structure of bones.

Organ Systems of the Human Body

Skeletal System Overview

The skeletal system is one of several organ systems in the human body, each with distinct structures and functions. The skeletal system works closely with other systems, such as the muscular and circulatory systems, to maintain overall health and function.

• Main Structures: Bones, tendons, ligaments, cartilage

• Main Functions:

  • Support: Provides structural support for the body (endoskeleton)

  • Protection: Shields internal organs (e.g., skull protects the brain, rib cage protects the heart and lungs)

  • Leverage: Facilitates movement by serving as attachment points for muscles

  • Storage of Minerals and Lipids: Stores essential minerals (e.g., calcium, phosphorus) and lipids (yellow bone marrow)

  • Blood Cell Production: Produces blood cells in red bone marrow (hematopoiesis)

Additional info: The skeletal system also plays a role in maintaining mineral homeostasis and acid-base balance.

Learning Outcomes

Key Objectives for Study

• Describe the major functions of the skeletal system.

• Classify bones according to shape and structure, giving examples of each type, and explain the functional significance of each.

• Explain types of bone markings and their significance.

• Identify the cell types in bone and list their major functions.

• Compare the structures and functions of compact bone and spongy bone.

• Compare the mechanisms of endochondral ossification and intramembranous ossification.

• Describe the remodeling and homeostatic mechanisms of the skeletal system.

• Discuss the effects of exercise, nutrition, and hormones on bone development and on the skeletal system.

• Explain the role of calcium as it relates to the skeletal system.

• Describe the types of fractures and explain how fractures heal.

• Summarize the effects of the aging process on the skeletal system.

Additional info: These outcomes guide the study of bone anatomy, physiology, and pathology.

6-1 Skeletal System

Components and Functions

The skeletal system consists of several key components that work together to support and protect the body.

• Bones: Rigid organs that form the skeleton and provide structure.

• Cartilages: Flexible connective tissue found in joints, ear, nose, and other areas.

• Ligaments: Connect bones to other bones, stabilizing joints.

• Tendons: Connect muscles to bones, enabling movement.

Primary Functions of the Skeletal System:

• Support: The endoskeleton maintains the shape and posture of the body.

• Storage of Minerals and Lipids: Bones store minerals such as calcium and phosphorus, and lipids in yellow bone marrow.

• Blood Cell Production: Red bone marrow produces red blood cells, white blood cells, and platelets.

• Protection: Bones protect internal organs from mechanical damage.

• Leverage: Bones act as levers to facilitate movement when muscles contract.

Classification of Bones:

• Shape: Bones are classified as long, short, flat, irregular, sesamoid, and sutural based on their shape.

• Structure: The internal structure of bones includes compact and spongy bone, as well as bone marrow.

Example: The femur is a long bone, the parietal bone is a flat bone, and the vertebrae are irregular bones.