Skeletal Tissue Vocabulary

Glossary

A

• Appositional growthAn increase in size and number of cells. – The process of bone widening and thickening by adding layers to the surface.
• Articular cartilageA flexible connective tissue found in joints, the ear, nose, and rib cage. Cartilage can be of three – Smooth hyaline cartilageThe most abundant cartilage type, found in joints, ribs, and the nose. covering joint surfaces to reduce friction.

C

• Calcification – The hardening of tissues due to calcium salt depositionThe process of bone matrix formation by osteoblasts..
• Calcitonin – A hormone from the thyroid that lowers blood calcium levels by inhibiting osteoclasts.
• Calcitriol – The active form of vitamin D, promoting calcium absorption in the intestines.
• Calculus – An abnormal calcified mass in tissues.
• Canaliculi – Tiny channelsProtein passages in the cell membrane that allow specific molecules to pass through. that connect osteocytes, allowing communication and nutrient exchange.
• Cartilage – A flexible connective tissue found in joints, the ear, nose, and rib cage.
• Central canal – A hollow canal in an osteon containing blood vessels and nerves.
• ChondrocytesMature cartilage cells housed in lacunae. – Mature cartilage cellsThe basic structural and functional units of life. housed in lacunae.
• Circumferential lamella – Outer layers of bone tissue that encircle the entire bone.
• Compact bone – Dense, strong bone tissue forming the outer layer of bones.
• Concentric lamellaeRings of bone matrix surrounding the central canal in an osteon. – Rings of bone matrix surrounding the central canal in an osteon.

D

• Deposition – The process of bone matrix formation by osteoblasts.
• Diaphysis – The shaft of a long bone.
• Diploë – The spongy boneA porous bone tissue found inside bones, providing lightweight support. layer sandwiched between compact boneDense, strong bone tissue forming the outer layer of bones. in flat bones.

E

• Elastic cartilage – A flexible cartilage type found in the ear and epiglottisA flap of cartilage that covers the trachea during swallowing to prevent food from entering the airw.
• Endochondral ossification – Bone formation replacing a cartilage model, common in long bones.
• Endosteum – A thin connective tissue lining the marrow cavityThe hollow space inside bones that contains bone marrow..
• Epiphyseal line – A remnant of the epiphyseal plateA growth plate in developing bones made of cartilage., marking where growth stopped.
• Epiphyseal plate – A growth plate in developing bones made of cartilage.
• Epiphysis – The expanded ends of a long bone.

F

• Fibrocartilage – A tough, shock-absorbing cartilage found in intervertebral discs and menisci.
• FracturesBreaks in bones due to stress or injury. – Breaks in bones due to stress or injury.

H

• Hard callus – A bony structure that stabilizes a fracture during healing.
• Hematoma – A blood clot that forms at the site of a fracture.
• Hyaline cartilage – The most abundant cartilage type, found in joints, ribsCurved bones forming the rib cage; articulate with thoracic vertebrae and most with the sternum., and the nose.
• Hydroxyapatite – A mineral form of calcium phosphate giving bone its hardness.
• Hypercalcemia – Excess calcium in the blood, leading to nervous and muscular dysfunction.
• Hypocalcemia – Low calcium levels in the blood, causing muscle spasms and weakness.

I

• Interstitial growth – Bone growth from within, increasing bone length.
• Interstitial lamellae – Layers of bone matrix found between osteonsThe structural unit of compact bone, consisting of concentric lamellae around a central canal..
• Intramembranous ossification – Bone formation from mesenchymal tissue, producing flat bones.

L

• LacunaeSmall spaces in bone tissue where osteocytes reside. – Small spaces in bone tissue where osteocytes reside.

M

• Marrow cavity – The hollow space inside bones that contains bone marrow.
• Mesenchyme – The embryonic connective tissue that gives rise to bone and cartilage.
• Metaphysis – The region between the epiphysisThe expanded ends of a long bone. and diaphysisThe shaft of a long bone., where bone growth occurs.
• Mineralization – The process of depositing mineralsInorganic elements essential for body function. into bone tissue.

O

• Ossification centers – Regions where bone formation begins.
• Osteoblasts Bone-forming cells that secrete osteoid. – Bone-forming cells that secrete osteoid.
• OsteoclastsBone-resorbing cells that break down bone matrix. – Bone-resorbing cells that break down bone matrix.
• OsteocytesMature bone cells that maintain bone tissue. – Mature bone cells that maintain bone tissue.
• Osteogenic cellsStem cells that develop into osteoblasts. – Stem cells that develop into osteoblasts.
• Osteoid – The organic matrix of bone before it becomes mineralized.
• Osteolysis – The breakdown of bone tissue by osteoclasts.
• Osteon – The structural unit of compact bone, consisting of concentric lamellae around a central canal.
• Osteoporosis – A disease characterized by weak, brittle bones due to decreased bone mass.

P

• Perforating canalsCanals that connect central canals, allowing blood flow between osteons. – Canals that connect central canalsA hollow canal in an osteon containing blood vessels and nerves., allowing blood flow between osteons.
• Perichondrium – A connective tissue layer surrounding cartilage.
• Periosteum – A fibrous membrane covering bones, providing blood supply and attachment points.
• PTH (Parathyroid Hormone)A hormone that increases blood calcium by stimulating osteoclasts. – A hormone that increases blood calcium by stimulating osteoclasts.

R

• Reabsorption – The breakdown and recycling of bone minerals into the bloodstream.
• Red marrow – Bone marrow that produces blood cells.
• Remodeling – The ongoing process of bone resorption and deposition to maintain strength.

S

• Sacrificial bonds – Molecular bonds in bone collagenA structural protein in the dermis that provides strength and elasticity. that break to absorb impact and reduce fracture risk.
• Soft callus – The cartilage and fibrous tissue that forms in early fracture healing.
• SpiculesSmall, needle-like pieces of bone found in spongy bone. – Small, needle-like pieces of bone found in spongy bone.
• Spongy bone – A porous bone tissue found inside bones, providing lightweight support.

T

• TrabeculaeThe lattice-like structures in spongy bone that support stress distribution. – The lattice-like structures in spongy bone that support stress distribution.
• Twister resistor – A term describing bone’s ability to resist twisting forces.

W

Y

• Yellow marrow – Fatty bone marrow found in long bones, serving as an energyThe capacity to do work or cause change. reserve.

Z

• Zone of bone deposition – The region where new bone tissue is added during growth.
• Zone of calcificationThe hardening of tissues due to calcium salt deposition. – The area where cartilage matrix hardens before becoming bone.
• Zone of cell proliferation – The region where chondrocytes multiply, increasing bone length.
• Zone of hypertrophy – The area where cartilage cells enlarge before calcifying.
• Zone of reserve cartilage – The resting layer of cartilage that serves as a growth reserve.