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Skeletal System Review Flashcards

Skeletal System Overview

  • The skeletal system is vital for the physical support and locomotion of an organism.
  • It is categorized into different types:
    • Hydrostatic
    • Exoskeleton
    • Endoskeleton (e.g., present in rats and other vertebrates)
  • Comprised of all bones, which are considered living organs made of various tissues.

Functions of the Skeletal System

  • Provides framework, giving shape and support to the body.
  • Protects internal organs.
  • Acts as a major attachment point for muscles, facilitating movement.
  • Facilitates hematopoiesis: formation of blood cells, mostly in red marrow of certain bones.
  • Serves as a storage organ for calcium and phosphorus compounds.

Bone Marrow

  • Contains two types:
    • Yellow bone marrow: stores fat.
    • Red bone marrow: responsible for blood cell production (hematopoiesis).

Bone Classification

  • The adult human skeleton has 206 bones, divided into five categories based on their shape and function:
    • Long Bones: Longer than wide;
    • Examples: Femur, tibia, fibula.
    • Short Bones: Cube-like,
    • Examples: Carpals, tarsals.
    • Flat Bones: Thin and curved,
    • Examples: Sternum, ribs, scapulae.
    • Irregular Bones: Complex shapes,
    • Examples: Vertebrae, facial bones.

Bone Structure Details

  • Diaphysis: Hollow shaft containing yellow marrow (medullary cavity).
  • Epiphysis: Wider ends filled with spongy bone; contains red marrow.
  • Metaphysis: Area where diaphysis meets epiphysis; contains epiphyseal plate in growing bones which becomes an epiphyseal line in adults.
  • Endosteum: Inner layer of bone cells aiding growth and remodeling.
  • Periosteum: Outer layer containing blood vessels and nerves, significant for attachment of tendons and ligaments.

Bone Cell Types

  1. Osteogenic Cells (Stem Cells): Multipotent cells that develop into bone cells.
  2. Osteoblasts: Form bone matrix and mineralize tissue.
  3. Osteocytes: Mature bone cells maintaining bone tissue and regulating mineral content.
  4. Osteoclasts: Resorb bone tissue, critical for growth and remodeling.

Axial and Appendicular Skeleton

Axial Skeleton:

  • Consists of:
    • Skull
    • Mandible
    • Hyoid
    • Ribs
    • Sternum
    • Vertebrae

Appendicular Skeleton:

  • Consists of:
    • Pectoral girdle
    • Pelvic girdle
    • Limbs

Differences Between Rat and Human Skeletons

  • Rats:
    • 57-60 vertebrae, specialized for balance with tails, opposable thumbs not present.
  • Humans:
    • 33 vertebrae, opposable thumbs allow grasping, no long tail.

Joints

  • Joints connect two or more bones. Key types:
    • Synovial Joints: Most common, allowing movement.
    • Non-Synovial Joints: Immovable,
    • Example: Sutures between skull bones.

Types of Synovial Joints:

  1. Hinge Joints: e.g. elbow, knee.
  2. Ball and Socket Joints: e.g. hip, shoulder.
  3. Pivot Joints: e.g. atlas and axis.
  4. Gliding Joints: e.g. wrist bones.
  5. Saddle Joints: e.g. thumb joint.
  6. Planar (Gliding): e.g. vertebrae.

Conclusion

  • The skeletal system is an intricate structure that supports the body, enables movement, and protects vital organs through a complex array of bones and joints. Understanding its components and functionalities is crucial in the field of biology and medicine, specifically related to anatomy and bodily mechanics.