chapter-40-muscle-biology-for-test-prep-examinations-solutions-sm17

Functions of a Skeleton

• Support: Provides framework for the body, maintaining its shape.

• Protection: Shields vital organs (e.g., skull protects the brain, ribcage protects the heart and lungs).

• Movement: Facilitates movement through connections with muscles (lever systems).

• Mineral Storage: Stores minerals such as calcium and phosphorus, releasing them into the bloodstream as needed.

• Blood Cell Production: Houses bone marrow, which produces blood cells (red and white).

Types of Animal Skeletons

1. Hydrostatic Skeleton:

   • Definition: A fluid-filled cavity surrounded by muscles; provides support through pressure.

   • Example: Earthworms utilize hydrostatic skeletons to aid in movement.

2. Exoskeleton:

   • Definition: A rigid external covering for the body; provides protection and support.

   • Example: Insects have exoskeletons made of chitin.

3. Endoskeleton:

   • Definition: An internal skeleton made of bone or cartilage; supports the body internally and allows for growth.

   • Example: Humans and other vertebrates possess endoskeletons.

Divisions of the Vertebrate Skeleton

• Axial Skeleton: Composed of the skull, vertebral column, ribs, and sternum.

• Appendicular Skeleton: Includes limbs and girdles (pectoral and pelvic) that support movement.

Structure and Function of Dense vs. Spongy Bone

• Dense Bone (Osteon System):

  • Structure: Composed of tightly packed osteons, providing strength and protection.

  • Function: Primarily supports weight and withstands stress.

• Spongy Bone (Canalicular Bone):

  • Structure: Lattice-like arrangement allowing for space; contains trabeculae.

  • Function: Provides lightweight support, houses bone marrow, and aids in shock absorption.

Red vs. Yellow Bone Marrow

• Red Bone Marrow:

  • Function: Produces red blood cells, white blood cells, and platelets; found mainly in flat bones and the ends of long bones.

• Yellow Bone Marrow:

  • Function: Stores fat and serves as an energy reserve; can be converted to red marrow in times of need.

Structural Types of Bones

1. Long Bones: Longer than they are wide; examples include femur and humerus.

2. Short Bones: Approximately equal in length and width; examples include carpals and tarsals.

3. Flat Bones: Thin and flat; examples include the skull, scapulae, and sternum.

4. Irregular Bones: Complex shapes; examples include vertebrae and pelvis.

Anatomical Regions of a Long Bone

• Diaphysis: Shaft or central part of a long bone.

• Epiphysis: Ends of the long bone; contains spongy bone and articulates with other bones.

• Metaphysis: Region between diaphysis and epiphysis, where growth occurs in children.

• Articular Cartilage: Smooth tissue covering the epiphysis, aiding in joint movement.

• Periosteum: Dense layer of vascular connective tissue enveloping the bones.

Endochondral vs. Intramembranous Bone Formation

• Endochondral Formation:

  • Definition: Bone develops from cartilage model; replaces cartilage with bone.

  • Example: Long bones such as femur form through this process.

• Intramembranous Formation:

  • Definition: Bone develops directly from mesenchymal tissue.

  • Example: Flat bones of the skull form this way.

Types of Joints and Joint Movements in the Human Skeleton

• Types of Joints:

  • Fibrous Joints: Immovable (e.g., sutures in the skull).

  • Cartilaginous Joints: Slightly movable (e.g., intervertebral discs).

  • Synovial Joints: Freely movable (e.g., knee and elbow).

• Types of Movements:

  • Flexion/Extension: Bending and straightening movements.

  • Abduction/Adduction: Movement away from and towards the body midline.

  • Rotation: Circular movement around an axis.