Skeletal System Overview

Study Notes

Introduction

The skeletal framework is a complex system of bones, cartilage, and ligaments providing structure, support, and protection for the body.
It plays a crucial role in movement, blood cell production, and mineral storage.

Skeletal Components

Bones: Hard, calcified tissues forming the majority of the skeleton.
- Different bone types exist: long bones (e.g., femur), short bones (e.g., carpals), flat bones (e.g., ribs), irregular bones (e.g., vertebrae), and sesamoid bones (e.g., patella).
- Bone composition includes collagenous proteins and minerals like calcium and phosphate.
- Bone structure features compact bone (dense outer layer) and spongy bone (porous inner layer) for strength and weight distribution.
Cartilage: Flexible connective tissue found in areas needing cushioning or support.
- Types of cartilage include hyaline, elastic, and fibrocartilage with varying degrees of flexibility and strength.
- Cartilage lacks blood vessels; healing is slower than bone.
Ligaments: Strong bands of fibrous connective tissue connecting bones to bones at articulations (joints).
- They provide stability and limit excessive movement at joints.

Functions of the Skeletal System

Support: Provides structural framework for the body.
Protection: Encloses and shields vital organs (e.g., skull protects the brain, rib cage protects the heart and lungs).
Movement: Acts as levers for muscles, facilitating locomotion and movement.
Blood cell production (hematopoiesis): Bone marrow within certain bones produces red and white blood cells and platelets.
Mineral homeostasis: Stores and releases minerals like calcium and phosphorus, crucial for various bodily functions.

Types of Skeletal Systems

Axial skeleton: Forms the central axis of the body, including the skull, vertebral column, and rib cage providing protection and support for vital organs.
Appendicular skeleton: Consists of the bones of the limbs (arms and legs), pectoral girdle (shoulder), and pelvic girdle (hips), enabling movement and interaction with the environment.

Joints (Articulations)

Joints are points where two or more bones meet.
Types of joints based on movement:
- Synarthroses (immovable): E.g., sutures in the skull.
- Amphiarthroses (slightly movable): E.g., pubic symphysis.
- Diarthroses (freely movable): E.g., shoulder and knee joints, commonly characterized by a joint cavity, articular cartilage, and ligaments.
Types of joints based on structure:
- Fibrous joints
- Cartilaginous joints
- Synovial joints

Bone Growth and Development

Intramembranous ossification: Bone forms directly from mesenchymal (embryonic) tissue, typical of flat bones.
Endochondral ossification: Bone forms by replacing hyaline cartilage, a characteristic of long bones.
Growth plates (epiphyseal plates) are significant for longitudinal bone growth during adolescence; eventually ossify to become epiphyseal lines.

Bone Remodeling and Repair

Bone is dynamic tissue continuously being remodeled and repaired.
Bone remodeling involves osteoclasts (bone-resorbing cells) and osteoblasts (bone-forming cells).
Repairs occur from the formation of a hematoma, followed by callus formation, and finally remodeling.

Skeletal Diseases

Osteoporosis: Loss of bone density, weakening bones and increasing fracture risk.
Arthritis: Inflammation of joints, causing pain and limited mobility.
Fractures: Breaks in the bone, requiring immobilization and healing.
Scoliosis: Abnormal sideways curvature of the spine.
Kyphosis: Exaggerated outward curvature of the thoracic spine.
Lordosis: Exaggerated inward curvature of the lumbar spine.

Aging Effects on the Skeleton

Bone density decreases with age, increasing fracture risk.
Joint mobility often decreases, limiting movement.
The natural healing process slows, with longer recovery times for injuries.

Description

Explore the complex structure and function of the skeletal framework in this quiz. Learn about the different types of bones, their composition, and the crucial role cartilage plays. Test your knowledge on how these components contribute to the body's movement, support, and protection.