Chapter 7: Bone Tissue

Comprehensive vocabulary flashcards covering the histology, anatomy, development, regulation, and pathology of bone tissue from Chapter 7 of BIOL 2401 Anatomy & Physiology I.

Osteology

The scientific study of bones.

Ligament

Connective tissue band that connects bone to bone.

Tendon

Connective tissue structure that connects muscle to bone.

Bone tissue (osseous tissue)

Connective tissue that is hardened by mineral deposition.

Bone organ

An entire bone structure containing multiple tissues, including bone tissue, cartilage, marrow, fat, nerves, and connective tissue.

Mineralization

The process of hardening bone tissue through mineral deposition.

Long bone

A bone that is longer than it is wide, such as the femur, humerus, radius, or tibia.

Short bone

A bone of approximately equal length and width, such as carpals and tarsals.

Flat bone

A thin, protective, often curved bone, such as the sternum, ribs, skull bones, or hip bones.

Irregular bone

A bone with a complex shape that does not fit into other shape categories, such as vertebrae.

Diaphysis

The shaft of a long bone that provides leverage.

Epiphysis

The enlarged end of a long bone.

Metaphysis

The transition zone between the epiphysis and diaphysis of a long bone; functions as the region of growth.

Periosteum

The external covering of a bone consisting of an outer fibrous layer of collagen and an inner osteogenic layer of bone-forming cells; aids in growth and repair.

Endosteum

The membrane lining the internal surfaces of a bone.

Articular cartilage

A layer of hyaline cartilage covering joint surfaces of bones.

Medullary cavity

The internal central cavity within the shaft of a long bone that contains bone marrow.

Epiphyseal plate

A layer of hyaline cartilage in the metaphysis where long bones grow in length.

Epiphyseal line

The bony remnant left behind after the epiphyseal growth plate closes in adulthood.

Red marrow

Bone marrow responsible for the production of blood cells (hematopoiesis).

Yellow marrow

Bone marrow that functions primarily in the storage of fats (triglycerides).

Diploë

The spongy bone middle layer sandwiched between two layers of compact bone in flat bones; absorbs shock and houses marrow spaces.

Osteogenic cell

A stem cell in bone that divides to produce osteoblasts.

Osteoblast

A bone-forming cell that builds bone and deposits the bone matrix.

Osteocyte

A mature bone cell residing in a lacuna that maintains the bone matrix and senses mechanical stress.

Osteoclast

A specialized cell that breaks down and resorbs bone tissue (osteolysis).

Lacunae

Small cavities within the bone matrix that house osteocytes.

Canaliculi

Tiny channels connecting adjacent lacunae that allow for the exchange of nutrients, metabolic wastes, and cellular signals.

Osteoid

The unmineralized organic component of the bone matrix.

Organic bone matrix

Constitutes approximately $\frac{1}{3}$ of the dry weight of bone matrix, mainly composed of collagen and protein-carbohydrate complexes, providing flexibility and shock absorption.

Inorganic bone matrix

Constitutes approximately $\frac{2}{3}$ of the dry weight of bone matrix, composed mostly of mineral salts ($85\%$ hydroxyapatite and $10\%$ calcium carbonate), providing hardness and strength.

Hydroxyapatite

The primary crystallized calcium phosphate salt making up $85\%$ of the inorganic mineral matter in bone.

Rickets

A condition characterized by soft, deformed bones caused by inadequate mineral deposition.

Osteogenesis imperfecta

A brittle bone disorder caused by a defect in collagen synthesis.

Osteon

The basic structural and functional unit of compact bone.

Central (Haversian) canal

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

Concentric lamellae

Circular layers or rings of calcified bone matrix surrounding a central canal in an osteon.

Perforating canals

Transverse channels that deliver blood vessels and nerves from the periosteum through compact bone to the central canals.

Trabeculae

Thin, interconnected plates of bone that form the structural network of spongy bone.

Intramembranous ossification

The process of bone development in which bone forms directly from embryonic mesenchymal connective tissue, producing flat skull bones and clavicles.

Endochondral ossification

The process of bone development in which bone forms by replacing a pre-existing hyaline cartilage model, producing most bones of the body.

Interstitial growth

The growth that increases the length of long bones through cartilage division at the epiphyseal plate and its replacement by bone.

Appositional growth

The growth that increases bone thickness and diameter through matrix deposition on the bone surface.

Zone of reserve cartilage

The region of resting hyaline cartilage located farthest from the diaphysis in the metaphysis.

Zone of cell proliferation

The metaphysis zone where chondrocytes actively divide and align into longitudinal columns.

Zone of cell hypertrophy

The metaphysis zone where chondrocytes cease division and enlarge significantly.

Zone of calcification

The metaphysis zone where the temporary cartilage matrix calcifies.

Zone of bone deposition

The metaphysis zone closest to the marrow cavity where cartilage breaks down and osteoblasts deposit new bone matrix.

Bone remodeling

The continuous coupled breakdown and rebuilding of bone tissue throughout life, replacing approximately $10\%$ of the skeleton each year.

Wolff's law

The physiological principle stating that bone architecture adapts and reinforces in response to the mechanical stresses placed upon it.

Parathyroid hormone (PTH)

A hormone secreted by the parathyroid glands that acts to raise blood calcium concentration when it falls below the normal range of $9.2\text{--}10.4\,\text{mg/dL}$.

Calcitonin

A hormone secreted by C cells of the thyroid gland that lowers blood calcium levels by inhibiting osteoclasts and stimulating osteoblasts.

Calcitriol

The active form of vitamin D that enhances calcium and phosphate absorption in the intestines.

Comminuted fracture

A bone fracture in which the bone shatters or breaks into $3$ or more pieces.

Greenstick fracture

An incomplete fracture in which one side of the bone breaks while the other bends, commonly seen in children.

Colles fracture

A fracture occurring at the distal end of the radius.

Pott fracture

An ankle fracture that involves breaks in both lower leg bones.

Osteoporosis

A skeletal disorder characterized by a severe loss of bone density, preferentially affecting metabolically active spongy bone and creating high fracture risks.