Skeletal System Overview

Skeletal System Overview

• The skeletal system forms a supportive framework of bones and connective tissues.
• Its functions include: protecting body tissues and organs, anchoring skeletal muscles.
• Main organs are bones and joints.

Types of Skeletons

• Exoskeletons: External skeletons made of chitin and calcium carbonate. Provide protection to insects and crustaceans. A disadvantage is the need to molt and limited growth potential.
• Endoskeletons: Internal skeletons of animals (vertebrates), composed of bone and cartilage. An advantage is growth with the animal. A disadvantage is less protection.

Main Functions of Skeletal System

• Support and Protection: Supports soft tissues, anchors muscles, protects internal organs.
• Movement: Works with the muscular system for movement.
• Blood Cell Production: Red bone marrow in some bones produces blood cells (red blood cells, white blood cells, and platelets). Red blood cells carry oxygen, white blood cells fight infection, and platelets help clot blood.
• Storage: Stores minerals (calcium, phosphorus), yellow marrow, and chemical energy (fatty acids).
• Homeostasis: Absorbs or releases calcium to maintain a stable body environment.

Bones of the Human Body

• An adult human skeleton has 206 bones.
• Bones are classified into long, short, irregular, flat, and sesamoid bones.
• Long bones: Support weight, facilitate movement (e.g., humerus, radius, ulna, femur).
• Short bones: Cube-shaped, provide stability (e.g., carpals, tarsals).
• Irregular bones: Complex shape, protect internal organs (e.g., vertebrae, sacrum).
• Flat bones: Protect organs (e.g., cranial bones, ribs, sternum).
• Sesamoid bones: Reinforce tendons (e.g., patella).
• The skeletal system is composed of two parts:
  • Appendicular skeleton (126 bones): Provides support and flexibility (mostly appendages and girdles).
  • Axial skeleton (80 bones): Protects internal organs (along the body's vertical axis).

Bone Tissue

• Compact bone: Dense outer layer of bone.
• Periosteum: Tough membrane covering and protecting the outer surface of the bone.
• Spongy bone: Lighter, less dense inner layer of bone containing pores and bone marrow.
• Bone marrow: Connective tissue producing blood cells.

Connective Tissues

• Ligaments: Attach bone to bone.
• Tendons: Attach muscle to bone.

Female vs. Male Skeletons

• Female pelvis is wider and flatter for childbirth.
• Female skeletons are generally less massive and dense than male skeletons.
• Female rib cage is more rounded and smaller.

Skeletal Diseases

• Osteoporosis: Loss of bone tissue, common in the elderly.
• Osteomalacia: Softening of bones due to vitamin D deficiency.
• Arthritis: Inflammatory disease damaging joints and surrounding tissue.
• Scoliosis: Side-to-side curve in the spine, often during adolescence.
• Bone cancers: Occur in approximately 1% of all cancers.
• Fractures, breaks, and strains: Bones can break with significant pressure (25-160 lbs). A compound fracture involves the bone breaking through the skin.

Explore the structure and functions of the skeletal system in this quiz. Understand the differences between exoskeletons and endoskeletons, as well as the multiple roles bones play in support, protection, and movement. Test your knowledge on how the skeletal system contributes to blood cell production and overall body function.