Connective tissue – Bone and Cartilage Flashcards
Origin of cartilage
Mesenchyme during the 5th week of development
General features of cartilage
Avascular, poor ability for regeneration
Growth types of cartilage
Appositional (from the surface) and interstitial (from the inside)
Perichondrium
covers cartilage, made of dense irregular tissue
Cell types in cartilage
Chrondroblasts and chondrocytes
Chondroblasts
Cells close to the surface, appositional growth, secrete the matrix
Chondrocytes
Embedded chondroblasts that occupy the lacunae, produce/maintain the ECM, interstitial growth
Isogenous groups
Cell clusters of divided chrondrocytes
Main type of collagen found in cartilage
Type II collagen
What attaches chondrocytes to the cell matrix?
multi adhesive glycoproteins
Territorial matrix
area that surrounds the lacunae that is richer in GAGs
Interterritorial matrix
matrix in-between the lacunae, less intensely staining
Types of cartilage
Hyaline, elastic, fibrocartilage
Hyaline cartilage
well developed perichondrium, dense irregular tissue, ECM has no visible fibers, chondrocytes are often in isogenous groups
Elastic cartilage
Well developed perichondrium, ECM has elastic fibers, chondrocytes are in large/distended lacunae
Fibrocartilage
Hybrid b/t hyaline and dense irregular connective tissue, does NOT have a perichondrium, has BOTH type I&II collagen
Chondrosarcoma
Malignant proliferation of cartilage, wide age range with a slight male predominance
Compact bone
Outer ridge shell of bone
Spongy bone
spicules/trabeculae on the inner side of the bone
Marrow cavity
Reticular, hemopoietic connective tissue or adipose tissue
Periosteum
Dense irregular tissue that covers the external layer of bone, will have 2 layers of bone is actively growing (external-fibrous and internal-osteogenic)
Osteoprogenitor cells
cells that form from the mesenchyme that will differentiate into osteoblasts
Organic bone matrix
Type I collagen, little ground substances, has unique multiadhesive glycoproteins to bind matrix material
Inorganic bone matrix
Most calcium phosphate, calcium carbonate, Mg, Na, K
Osteoblasts
principle bone-forming cells, only found at the boundary between bone and the adjacent tissue
Osteocytes
Osteoblast that are trapped in the matrix, housed in lacunae, form canaliculi to connect the lacunae
Osteoclasts
Large-multinucleated cells; reabsorb the bone
Clear zone
Actin-rich area that osteoclasts attach to
Ruffled border
part of the osteoclast in direct contact with the bone
Osteosarcoma
Malignant proliferation of osteoblasts, 20% of primary bone cancers, high metastatic
Osteoid osteoma
Small, benign tumor usually in the appendicular skeleton or spine that causes acute night pains
Paget’s disease
Enlarged, deformed bones that are prone to fracture
Primary (woven) bone
Immature type of bone laid down for bone repair
Secondary (lamellar) bone
main structural unit is the osteon
Haversian canal
Longitudinal canal with the neurovascular bundle
Lamellae
Surrounds the canals concentrically
Canaliculi
Connect the lacunae
Lacunae
Houses the osteocytes between the lamellae
Volkmann’s canal
Transverse canals with neurovascular bundles
Interstitial lamellae
Remnants of the old Haversian system
Types of ossification
Intramembranous and Endochondrial
Intramembranous ossification
Bone formed directly from connective tissue
Primary ossification center
Region of initial intramembranous ossification
Endochondrial ossification definition
Replacement of cartilaginous tissue with bony tissue
Endochondrial ossification steps
1) hyaline cartilage model forms 2)cartilage grows 3)cuff of bone formed around diaphysis 4)midregion of cartilage calcifies (lack of nutrients) 5)chondrocytes die 6) blood vessels/osteoprogenitors degenerate cartilage 7) osteoblasts secrete bone matrix 8)matrix replaces cartilage
Primary ossification center for long bones
Diaphysis
Secondary ossification center for long bones
Epiphyses
Epiphyseal plate zones
Reserve cartilage, proliferation, hypertrophy, calcification, ossification
Epiphyseal plate zones: reserve cartilage
hyaline cartilage with chondrocytes
Epiphyseal plate zones: Proliferation
rapid tissue growth, chondrocytes divide to form stacked cells parallel to the long axis of the bone
Epiphyseal plate zones: Hypertrophy
Chondrocytes swell in size
Epiphyseal plate zones: Calcification
Chondrocytes lost via apoptosis, matrix is calcified
Epiphyseal plate zones: ossification
Osteoblasts synthesize bone tissue over the calcified cartilage
