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.