Bone, Cartilage and Osteogenesis - Hovorka Flashcards
What are the 3 types of cells found in bone?
Osteoblasts
Osteocytes
Osteoclasts
Where are osteoblasts found?
At border between bone and periosteum
What do osteoblasts secrete?
Uncalcified bone matrix
Osteoblasts differentiate from what? Where?
Progenitor cells
Periosteum
From what do osteocytes differentiate?
Osteoblasts - only once they are surrounded by calcified bone matrix
Where are osteocytes found?
In lacunae
How do osteocytes receive nutrients?
From a central artery via their connections to neighboring cells in contact with the artery
What type of junctions to the osteocyte processes contain?
Gap junctions
What are osteoclasts?
Large, multinucleated cells that degrade bone matrix
From what do osteoclasts differentiate?
Monocytes
How do osteoclasts degrade bone matrix?
By secretion of protons and lysozomal enzymes
Differentiation and activity of osteoclasts increases due to which hormone?
Parathyroid hormone
What are the organic components of bone matrix?
Mostly type I collagen
Very little ground substance
How does bon become calcified?
By the deposition of calcium phosphate (hydroxyapatite) around the collagen fibers, displacing water
How is mature bone matrix organized?
Lamellae and osteons surrounding small central arteries
What is periosteum made of?
Dense connective tissue - containing fibroblasts and collagen bundles
The periosteum is continuous with what?
The tendons that insert on it
Where are the progenitor cells contained?
In the periosteum
What is the cylindrical unit of mature bone called?
Osteon
What are lamellae?
Rings of calcified bone matrix with collagen fibers oriented in a single direction
What contains the vessels and nerves in bone?
Haversian canal (central canal)
What are canaliculi?
Canals that interconnect lacunae within the osteon and facilitate the transport of nutrients and wastes between osteocytes
What interconnects central canals and periosteum/endosteum?
Perforating canals
What are the 5 steps to healing bone?
- Hematoma
- Connective tissue invades
- Precallus - hyaline cartilage model
- Callus - calcification and ossification of cartilaginous model creates immature bone
- Mature bone
How do nutrients/wastes get in/out of cartilage?
Diffuse through the matrix to/from the surrounding perichondrium
What are the 2 cells types in cartilage?
Chondroblasts
Chondrocytes
Chondroblasts differentiate from what cells?
Progenitor cells
Where are progenitor cells found?
Border between bone and perichondrium
