Bone & Skeletal System – Video Review (Vocabulary Flashcards)

A comprehensive set of vocabulary flashcards covering the major concepts from the bone and skeletal system lecture notes.

Skeletal system functions

Support, protection, movement, mineral homeostasis (calcium), hematopoiesis, and fat storage.

Hematopoiesis

Blood cell production, occurring primarily in red bone marrow.

Mineral homeostasis

Maintenance of mineral reserves in bone, especially calcium; about 99% of body calcium stored in bone.

Yellow marrow

Fat storage within the medullary cavity; energy reserve.

Long bone

Bone longer than it is wide with a diaphysis and two epiphyses; optimized for leverage and movement.

Short bone

Cube-like bones (e.g., carpals, tarsals) that provide stability with limited motion.

Wormian bone

Small extra bone formed within cranial sutures.

Flat bone

Thin, curved bones with two layers of compact bone sandwiching cancellous bone (diploe); e.g., sternum.

Irregular bone

Bones of complex shapes (e.g., vertebrae) that don’t fit other categories.

Sesamoid bone

Small bone enclosed within a tendon, such as the patella, to improve mechanical advantage.

Diaphysis

Shaft of a long bone; hollow cylinder with compact bone around a medullary cavity.

Epiphysis

Expanded end of a long bone; contains spongy bone and red marrow.

Metaphysis

Region between diaphysis and epiphysis; contains growth area in developing bone.

Articular cartilage

Hyaline cartilage covering joint surfaces to reduce friction and absorb shock.

Periosteum

Dense outer membrane with two layers: an outer fibrous layer and an inner osteogenic layer.

Endosteum

Membrane lining the inner surfaces of bone, including the medullary cavity; contains osteogenic cells.

Medullary cavity

Central cavity of diaphysis containing bone marrow (red in youth, yellow in adults).

Red bone marrow

Site of hematopoiesis; found in trabecular spaces of certain bones.

Osteon

Basic unit of compact bone; concentric lamellae arranged around a central (Haversian) canal.

Concentric lamellae

Rings of bone matrix within an osteon formed during remodeling.

Interstitial lamellae

Lamellae filling spaces between osteons due to remodeling.

Circumferential lamellae

Lamellae that encircle the entire bone (inner and outer surfaces).

Lacunae

Small chambers containing osteocytes within bone matrix.

Canaliculi

Tiny channels that connect lacunae, allowing nutrient and waste exchange between osteocytes and vessels.

Compact bone

Dense, solid bone tissue forming the outer layer and containing osteons.

Spongy bone (trabecular bone)

Porous, lattice-like bone tissue with trabeculae; houses red marrow.

Sharpey’s fibers

Collagen fibers that anchor the periosteum to the underlying bone.

Osteoblasts

Bone-forming cells that produce matrix and initiate mineralization; mature into osteocytes.

Osteocytes

Mature bone cells housed in lacunae; maintain bone tissue and communicate via canaliculi.

Osteoclasts

Large, multinucleated cells that resorb bone by secreting acids and enzymes.

Osteogenic cells (osteoprogenitor cells)

Stem cells that differentiate into osteoblasts to form bone.

Endochondral ossification

Bone formation from a cartilage model; forms most bones, including long bones; involves primary and secondary ossification centers.

Intramembranous ossification

Direct bone formation from mesenchyme; forms flat bones (skull, clavicles) without a cartilage model.

Primary ossification center

First site of bone formation in endochondral ossification, typically in the diaphysis.

Secondary ossification center

Site of bone formation in epiphyses; appears after birth.

Epiphyseal plate (growth plate)

Cartilaginous area between epiphysis and metaphysis responsible for longitudinal growth; becomes the epiphyseal line after growth ends.

Epiphyseal line

Radiographic line indicating closure of the growth plate and cessation of lengthwise growth.

Interstitial growth

Growth in length; chondrocyte proliferation within the growth plate.

Appositional growth

Growth in bone diameter/thickness via periosteal bone formation.

Ossification

Process of bone tissue formation.

Calcification

Deposition of calcium salts in tissues; mineralization of osteoid in bone.

Growth hormone (GH)

Pituitary hormone that stimulates growth; acts largely through IGF-1 to promote bone growth in children.

IGF-1 (insulin-like growth factor 1)

Mediator of GH effects on bone; promotes chondrocyte and osteoblast activity.

Hypothalamus

Brain region that produces GHRH to stimulate GH release from the pituitary.

GHRH (growth hormone-releasing hormone)

Hypothalamic hormone that stimulates pituitary GH secretion.

Thyroid gland

Gland producing calcitonin and thyroid hormones; involved in calcium regulation.

Calcitonin

Thyroid hormone that lowers blood calcium by inhibiting osteoclast activity.

Parathyroid hormone (PTH)

Parathyroid hormone that raises blood calcium by increasing bone resorption and activating vitamin D.

Calcitriol

Active form of vitamin D; increases calcium and phosphate absorption from gut and supports bone mineralization.

Hypocalcemia

Low blood calcium; triggers PTH release and bone resorption.

Hypercalcemia

High blood calcium; can suppress PTH and calcitriol production.

Gigantism

Excess GH before epiphyseal closure in childhood; excessive linear growth.

Acromegaly

Excess GH after epiphyseal closure in adulthood; thickened bones of face, hands, and feet.

Estrogen

Hormone that protects bone by inhibiting osteoclasts; deficiency contributes to osteoporosis after menopause.

Testosterone

Sex hormone that supports bone formation and density; contributes to peak bone mass.

Osteopenia

Lower-than-normal bone mineral density; precursor to osteoporosis.

Osteoporosis

Severely reduced bone mass and density leading to porous bones and fracture risk.

Weight-bearing exercise

Physical activity that loads bones (e.g., squats) to stimulate bone formation.

Strain magnitude

Amount of mechanical load applied to bone; larger magnitudes stimulate more bone formation.

Strain rate

Speed of loading; higher rates (e.g., jumping) can enhance bone adaptation.

Strain frequency

How often loading occurs; repeated loading promotes bone health.

Tensile forces

Forces that stretch or pull on bone; collagen provides resistance.

Compressive forces

Forces that push bones together; hydroxyapatite provides resistance.

Torsional forces

Twisting forces acting on bone; architecture resists torsion.

Hydroxyapatite

Calcium phosphate mineral that provides bone rigidity in combination with collagen.

Collagen

Protein giving bone tensile strength and a scaffold for mineral deposition.

Extracellular matrix (bone)

Composite of water, collagen fibers, and mineral salts (hydroxyapatite) that forms bone.

Lacunocanalicular system

Network of lacunae and canaliculi enabling osteocyte nutrition, signaling, and waste transfer.