Understanding the Human Skeletal System

Sep 16, 2024

Human Skeletal System

Overview

  • Skeletal system includes bones and connective tissues (ligaments, tendons, cartilage).
  • Bones are living tissues.
  • Functions:
    • Support and protect the body.
    • Store minerals.
    • Produce red and white blood cells.
    • Facilitate movement with muscles (musculoskeletal system).

Types of Skeletal Systems in Organisms

  • Hydrostatic Skeleton: Fluid-filled, e.g., earthworms.
  • Exoskeleton: Hard outer layer, e.g., insects (made of chitin, molting required for growth).
  • Endoskeleton: Internal skeleton, e.g., humans.

Structure of the Human Skeleton

  • Total bones: 206 in adults (more in babies due to fusion).
  • Divisions:
    • Axial Skeleton: Skull, ear bones, hyoid, vertebral column, rib cage.
    • Appendicular Skeleton: Arms, shoulders, legs, pelvic girdle.

Classification of Bones by Shape

  • Long Bones: Cylindrical, longer than wide (e.g., femur, tibia, humerus).
  • Short Bones: Cube-like (e.g., carpals, tarsals).
  • Sesamoid Bones: Roundish (e.g., patella).
  • Flat Bones: Thin and curved (e.g., skull bones, scapulae).
  • Irregular Bones: No specific shape (e.g., vertebrae).

Bone Tissue

  • Compact Bone: Hard outer layer.
  • Spongy Bone: Contains bone marrow (red and yellow marrow).
    • Red Marrow: Produces blood cells and platelets.
    • Yellow Marrow: Stores fat.

Bone Cells

  • Osteoblasts: Build bone, mature into osteocytes.
  • Osteocytes: Maintain bone structure.
  • Osteoclasts: Break down bone using lysosomes and acids.
  • Chondroblasts: Produce cartilage, mature into chondrocytes.

Bone Remodeling

  • Regular replacement process (5-10% annually).
  • Responds to stress and injury.
  • Releases minerals like calcium.

Bone Growth

  • Length growth ceases in early adulthood; diameter growth can continue.
  • Involves various zones (growth plate zones).

Bone Fractures

  • Fracture Hematoma: Blood collection at break site.
  • Callus Formation: Internal (cartilage) and external (cartilage + bone) calluses form.
  • Healing time varies (typically 6-8 weeks).

Disorders and Conditions

  • Osteogenesis Imperfecta: Genetic disorder affecting collagen production, leading to brittle bones.
    • No cure; treatment focuses on mobility and fracture prevention.

Interesting Facts

  • Bones are vascular with a rich blood supply.
  • In emergencies, medications/fluids can be delivered through bones similar to IV.

The Amoeba Sisters emphasize the interconnectedness of the body's systems and the importance of staying curious about biological processes.