Study Guide Chapter 5

Skeletal System

Comprises bones, cartilage, ligaments, joints, and bone marrow.

Bone Marrow

Contains hematopoietic stem cells for blood cell production.

Cartilage

A semi-rigid connective tissue that is weaker but more flexible than bone.

Types of Cartilage

Hyaline, fibrous, and elastic.

Functions of Cartilage

Supports tissues, provides a gliding surface for joints, and serves as a model for bone formation.

Interstitial Growth of Cartilage

Growth from within itself, lengthwise at the epiphyseal plate.

Appositional Growth of Cartilage

Growth along the outside edge or periphery, increasing diameter and thickness.

Flat Bones

Bones with thin and flat surfaces.

Long Bones

Bones that are greater in width and length, and are the most common.

Short Bones

Bones approximately equal in width and length.

Irregular Bones

Bones with an irregular shape.

Osteoprogenitor Cells

Stem cells located in the periosteum and endosteum.

Osteoblasts

Cells that secrete osteoid (bone matrix).

Osteocytes

Mature bone cells that maintain bone matrix, found in lacunae.

Osteoclasts

Cells that dissolve bone matrix through osteolysis.

Composition of Bone Matrix

Primarily collagen fibers and ground substance of hydroxyapatite (calcium phosphate crystals).

Diaphysis

The shaft of a long bone.

Epiphysis

The expanded ends of a long bone.

Metaphysis

The region between the diaphysis and epiphysis.

Articular Cartilage

Hyaline cartilage covering the epiphyses to reduce friction and absorb shock.

Medullary Cavity

The hollow space in the diaphysis containing bone marrow.

Endosteum

The membrane lining the internal bone surface.

Periosteum

The outermost covering of bone, made of dense irregular connective tissue.

Compact Bone

Dense bone found at the perimeter of long bones, composed of osteons.

Osteon

The functional unit of compact bone.

Central Canal

Contains blood vessels and nerves in an osteon.

Concentric Lamellae

Rings of matrix that make up an osteon.

Lacunae

Spaces in bone that house osteocytes.

Canaliculi

Projections for communication between osteocytes.

Perforating Canals

Horizontal channels in bone that contain blood vessels and nerves.

Circumferential Lamellae

Outer layers of bone that surround the osteons.

Spongy Bone

Porous bone found in the epiphyses and center of bones, consisting of trabeculae.

Trabeculae

Parallel lamellae in spongy bone that contain lacunae and osteocytes.

Intramembranous Ossification

The process by which mesenchyme forms flat bones.

Endochondral Ossification

The process where a hyaline cartilage model forms most bones.

Vitamin A

Activates osteoblasts.

Vitamin C

Essential for collagen production.

Vitamin D

Facilitates calcium and phosphate absorption.

Healing a Fracture

1. Fracture hematoma forms, 2. Fibrocartilaginous callus forms, 3. Hard callus forms, 4. Compact bone replaces callus.