Bone Tissue - Anatomy and Physiology I Flashcards

Vocabulary flashcards covering bone tissue structures, cells, compact and spongy bone features, long bone anatomy, bone classification, and ossification pathways based on Anatomy and Physiology I notes.

Skeletal System

The body system composed of bones, cartilage, and ligaments that functions to support the body, allow movement, protect internal organs, produce blood cells, and store minerals such as calcium and phosphate.

Bone Tissue

An active and living connective tissue composed of living cells surrounded by a hard extracellular matrix (ECM) that undergoes constant remodeling based on stress, growth, healing, and calcium needs.

Bone Remodeling

The process where old bone tissue is removed through resorption and new bone tissue is formed through ossification.

Inorganic Matrix

The non-cellular portion of the bone matrix that makes up 70% of its structure, consisting of about 2/3 calcium phosphate as hydroxyapatite crystals to provide hardness and compression resistance.

Hydroxyapatite Crystals

Rigid calcium phosphate crystals formed within the inorganic bone matrix that give bone its stiffness, hardness, and strength.

Organic Matrix

The non-cellular portion of the bone matrix making up 25% of its structure, composed of about 1/3 collagen fibers to provide flexibility, tensile strength, and shock absorption.

Osteogenic Cells

Undifferentiated mesenchymal stem cells found in the innermost layer of the periosteum and inner lining of the endosteum that divide to produce osteoblasts and assist in fracture repair.

Osteoblasts

Immature bone-forming cells derived from osteogenic cells located on existing bone surfaces, periosteum, and endosteum that synthesize osteoid and initiate calcification.

Osteoid

An unmineralized organic bone matrix mainly composed of collagen fibers produced by osteoblasts during bone synthesis.

Calcification

The process during bone synthesis where calcium builds up in the osteoid matrix, causing the tissue to harden.

Osteocytes

Mature, multinucleated bone cells located within lacunae that maintain the bone matrix, regulate calcium and phosphate levels, and signal osteoblasts and osteoclasts for remodeling.

Lacunae

Tiny cavities within the hard bone matrix that house osteocytes.

Osteocytic Osteolysis

The process by which mature osteocytes release calcium ions from the surrounding matrix into the bloodstream.

Osteoclasts

Large, multinucleated cells derived from white blood cells that reside on bone surfaces and perform bone resorption by secreting acids to dissolve minerals and organic components.

Bone Resorption

The enzymatic and acid-mediated breakdown of the mineral and organic components of bone matrix by osteoclasts.

Compact Bone

Dense, solid, and tightly packed bone tissue organized into osteons that forms the outer layer of all bones and the diaphysis of long bones to resist physical stress.

Osteon

The cylindrical, functional structural unit of compact bone composed of concentric lamellae surrounding a central canal.

Concentric Lamellae

Circular rings of hard bone matrix that surround the central canal inside an osteon.

Interstitial Lamellae

Layers of bone matrix located in the gaps and spaces between individual osteons.

Circumferential Lamellae

Layers of bone matrix located along the outer edge of a bone that encircle multiple osteons.

Central Canal (Haversian Canal)

A longitudinal channel running through the center of an osteon that contains blood vessels and nerves.

Perforating Canals (Volkmann's Canals)

Transverse channels that connect blood vessels and nerves between central canals of adjacent osteons.

Canaliculi

Tiny channels in the bone matrix that connect lacunae with each other and with blood vessels, allowing osteocytes to communicate and share nutrients.

Spongy Bone

A light, porous bone tissue made of a trabecular framework located deep to compact bone and inside flat bones and long bone epiphyses.

Trabeculae

Thin struts of bone that form the supportive open framework of spongy bone.

Red Bone Marrow

Specialized tissue situated within the spaces of spongy bone trabeculae responsible for producing blood cells.

Yellow Bone Marrow

Adipose-rich tissue stored within the medullary cavity of long bones that functions in fat storage.

Periosteum

A thick connective tissue membrane covering the outer surface of bones, excluding joint surfaces, where osteoblasts and osteoclasts reside.

Endosteum

A thin membrane lining the internal surfaces of bone, including the medullary cavity and spongy bone trabeculae.

Diaphysis

The central shaft of a long bone, primarily made of compact bone, containing the internal medullary cavity.

Epiphysis

The expanded ends of a long bone, composed mostly of spongy bone filled with red marrow and capped with articular cartilage.

Epiphyseal Line

A visible remnant line between the epiphysis and diaphysis in adult bones where the cartilaginous epiphyseal plate allowed childhood bone elongation.

Articular Cartilage

A smooth layer of hyaline cartilage covering the epiphyses at joint surfaces to reduce friction and absorb shock.

Long Bones

Bones that are longer than they are wide, consisting of a diaphysis and two epiphyses, designed for movement and weight support (e.g., femur, humerus).

Short Bones

Cube-shaped bones with roughly equal length, width, and height that provide stability with limited mobility (e.g., carpals, tarsals).

Flat Bones

Thin, slightly curved bones consisting of spongy bone sandwiched between compact bone layers, specialized for organ protection and muscle attachment (e.g., skull, sternum).

Irregular Bones

Bones with complex, unique shapes that do not fit standard structural categories (e.g., vertebrae, pelvic bones).

Sesamoid Bones

Small, round bones embedded within tendons to protect tendons and reduce friction (e.g., patella).

Bone Ossification

The process by which new bone tissue is synthesized and formed.

Intramembranous Ossification

A bone development process where bone forms directly from a fibrous connective tissue membrane without a prior cartilage stage, producing flat bones such as the skull and clavicles.

Endochondral Ossification

A bone development process where bone tissue replaces a pre-existing hyaline cartilage model, responsible for forming most bones including long, short, and irregular bones.

Primary Ossification Center

The region in the center of the diaphysis during endochondral ossification where invading blood vessels bring mesenchymal cells to form spongy bone.

Secondary Ossification Center

The region appearing in the epiphyses of bones after birth during endochondral ossification where cartilage is replaced by spongy bone without forming a medullary cavity.