Chapter 06: Bones and Skeletal Tissues - Vocabulary

Vocabulary flashcards covering skeletal cartilages, bone functions, classifications, anatomy, cells, histology, ossification, remodeling, and bone disorders.

Skeletal Cartilage

Highly resilient, molded cartilage tissue consisting primarily of water that contains no blood vessels or nerves.

Perichondrium

A layer of dense connective tissue surrounding cartilage that helps resist outward expansion and contains blood vessels for nutrient delivery.

Hyaline Cartilage

The most abundant skeletal cartilage type, containing collagen fibers only; provides support, flexibility, and resilience in articular, costal, respiratory, and nasal areas.

Elastic Cartilage

Cartilage similar to hyaline cartilage, but containing both collagen and elastic fibers; located in the external ear and epiglottis.

Fibrocartilage

Cartilage with thick collagen fibers that provides great tensile strength; found in the menisci of the knee, pubic symphysis, and intervertebral discs.

Appositional Growth

Cartilage or bone growth in which new matrix is laid down on the surface by cells in the surrounding membrane.

Interstitial Growth

Cartilage growth in which chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within.

Hematopoiesis

Blood cell formation that occurs in the red bone marrow of certain bones.

Osteocalcin

A hormone produced by bones that helps regulate insulin secretion, glucose homeostasis, and energy expenditure.

Axial Skeleton

The division of the skeleton forming the long axis of the body, consisting of the skull, vertebral column, and rib cage.

Appendicular Skeleton

The division of the skeleton consisting of the bones of the upper and lower limbs and the girdles that attach limbs to the axial skeleton.

Long Bones

Bones that are longer than they are wide, containing a medullary cavity extending the length of the shaft, such as most limb bones.

Short Bones

Cube-shaped bones located in the wrist and ankle.

Sesamoid Bones

Special short bones that form within tendons, such as the patella.

Flat Bones

Thin, flat, and slightly curved bones, such as the sternum, ribs, and most cranial bones.

Irregular Bones

Bones with complicated shapes that do not fit other categories, such as vertebrae and hip bones.

Compact Bone

The dense outer layer on every bone that appears smooth and solid to the naked eye.

Spongy Bone

Internal bone tissue composed of a honeycomb of small, needle-like or flat pieces called trabeculae.

Diploë

The internal layer of spongy bone found within short, irregular, and flat bones.

Diaphysis

The tubular shaft forming the long axis of a long bone, consisting of compact bone surrounding a central medullary cavity.

Epiphyses

The ends of a long bone consisting of compact bone externally and spongy bone internally, covered by articular cartilage on joint surfaces.

Periosteum

A white, double-layered membrane covering external bone surfaces (except joints), consisting of an outer fibrous layer and an inner osteogenic layer.

Endosteum

A delicate connective tissue membrane covering internal bone surfaces, lining canals of compact bone and trabeculae of spongy bone.

Osteoprogenitor Cells

Mitotically active stem cells located in the periosteum and endosteum that differentiate into osteoblasts or bone-lining cells.

Osteoblasts

Actively mitotic bone-forming cells that secrete unmineralized bone matrix called osteoid.

Osteoid

Unmineralized bone matrix secreted by osteoblasts, composed of collagen and calcium-binding proteins.

Osteocytes

Mature bone cells in lacunae that no longer divide, functioning to maintain the bone matrix and sense mechanical stress or strain.

Bone-Lining Cells

Flat cells found on bone surfaces that help maintain matrix; termed periosteal cells on external surfaces and endosteal cells on internal surfaces.

Osteoclasts

Giant, multinucleate bone-resorbing cells derived from hematopoietic stem cell lineage, possessing a ruffled border to increase enzymatic degradation area.

Osteon (Haversian System)

The structural unit of compact bone consisting of an elongated cylinder running parallel to the long axis, made of concentric rings of lamellae.

Central (Haversian) Canal

A canal running through the core of each osteon that contains blood vessels and nerve fibers.

Perforating (Volkmann's) Canals

Canals lined with endosteum that lie at right angles to central canals, connecting blood vessels and nerves of the periosteum, medullary cavity, and central canal.

Canaliculi

Hairlike canals connecting lacunae to each other and to the central canal, allowing osteocytes to communicate and exchange nutrients and wastes.

Hydroxyapatites

Inorganic mineral salts (mainly tiny calcium phosphate crystals) making up 65% of bone mass, responsible for bone hardness and resistance to compression.

Endochondral Ossification

The process of bone development in which bone forms by replacing a pre-existing hyaline cartilage model.

Intramembranous Ossification

The process of bone development in which bone forms directly from fibrous connective tissue membranes formed by mesenchymal cells.

Parathyroid Hormone (PTH)

A hormone released by the parathyroid glands in response to falling blood calcium levels that stimulates osteoclasts to resorb bone matrix.

Wolff's Law

An anatomical principle stating that bones grow or remodel in response to the physical demands and stresses placed on them.

Osteomalacia

A disease in adults characterized by poorly mineralized, soft, and weak bones due to inadequate calcium salt deposition in osteoid.

Rickets

A condition in children equivalent to osteomalacia, caused by vitamin D deficiency or insufficient calcium, resulting in bowed legs and deformed bone ends.

Osteoporosis

A group of bone diseases in which bone resorption outpaces bone deposit, causing a decline in bone mass while matrix composition remains normal.

Paget's Disease

A bone disorder characterized by excessive and haphazard bone deposit and resorption, producing abnormally soft and weak Pagetic bone.