Skeletal System - Key Lecture Notes

Overview

• The skeletal system is a significant organ system in the body.
• Human body comprises 206 bones.
• Learning anatomy involves understanding vocabulary (roots of words help).

Key Terms and Word Roots

• Osteo: bone
• Sido/Site: cell
• Genic: to build
• Chondro: cartilage
• Peri: around
• Indo: inside
• Heme/Hemato: blood
• Clast: to break
• Enter: between
• Poi: to produce
• Blast: build (Latin: bud)

Functions of the Skeletal System

1. Support: Framework for the body, supporting organs and the skeleton itself.
2. Protection: Protects vital organs (e.g., rib cage, skull).
3. Movement: Provides attachment points for muscles.
4. Inorganic Salt Storage: Stores minerals like calcium and phosphorus.
5. Hematopoiesis: Blood cell formation occurs in red bone marrow.
6. Energy Storage: Fat storage in yellow marrow.

Bone Structure

• Bone Tissue: A connective tissue, vascularized, and biphasic (organic and inorganic phases).
  • Organic Phase: Bone cells and collagen (flexibility & strength).
  • Inorganic Phase: Calcium phosphate providing rigidity.

Bone Types

• Compact Bone: Dense outer layer, provides structural strength.
• Spongy Bone: Contains trabeculae, light and supports bone marrow.

Bone Membranes

• Periosteum: Double-layered protective membrane around bone.
• Endosteum: Lines the inner surfaces of bones.

Cartilage and the Embryonic Skeleton

• Hyaline Cartilage: Forms preliminary shapes for bone formation.
• Elastic Cartilage: Found in ear and epiglottis.
• Fibrocartilage: Provides tough support in intervertebral discs and knees.

Bone Development and Age

• Epiphyseal Plates: Growth plates that eventually fuse as we age.
• Bone aging: Determined by characteristics such as density and epiphyseal plate status.

Bone Classification

• Long Bones: Shaft and two ends (e.g., femur, humerus).
• Short Bones: Cube-like (e.g., carpals).
• Flat Bones: Thin, protective (e.g., skull, ribs).
• Irregular Bones: Complex shapes (e.g., vertebrae, hip bones).
• Sesamoid Bones: Develop within tendons (e.g., patella).
• Wormian/Sutural Bones: Extra bone pieces within sutures of the skull.

Important Concepts

• Diaphysis: Shaft of a long bone.
• Epiphysis: Ends of a long bone.
• Yellow Marrow: Fat storage.
• Red Marrow: Blood cell production.
• Trabeculae: Structural support within spongy bone.

Real vs. Fake Bones in Labs

• Real bones have characteristics such as ossification levels and growth plate indicators.
• Fake bones are anatomically correct but less fragile.

Conclusion

• Understanding the skeletal system involves both structural and functional aspects.
• Bones and cartilages work together to provide support, protection, movement, and storage in the body.