Bones and Cartilage Flashcards
What are the three types of Cartilage?
1-Hyaline
2-Elastic
3-Fibrocartilage
What are 4 main differences between cartilage and CT proper?
1-Avascular
2-Only one cell type-chondrocyte
3-Type II collagen
4-Ground substance has aggregan(in hyaline cartilage) and chondronectin
What are cartilage cells derived from?
Mesenchymal stem cells
Which amino acids are important for type I collagen?
- Glycine (33%)
- hydroxyproline (modified proline
- hydroxylysine (modified lysine)
What is critical for amino acid hydroxylation? (absence may lead to scurvy)
Vitamin C
What is the general organization of collagen fibers?
Type I and III fibrils associate to form fibers, type II remains as a fibril with finer structure
What gives tensile strength and resilience to cartilage?
proteoglycan aggregates binding to water and ions
Hyaline cartilage is _________distributed. It has both _______ and _________ locations
Widely, permanent, transient
What is hyaline cartilage primarily made of?
Type II collagen fibrils
What attaches cells to the ECM in hyaline cartilage matrices?
Chondronectin
What surrounds permanent hyaline cartilage? (except articular)
Perichondrium (Type I fibers)
What doe chondroblasts and young chondrocytes do?
Secrete ECM
Where do chondrocytes reside?
Lacunae
Darker staining Matrix, rich in GAGs, found surrounding lacunae is called what?
Territorial matrix
Matrix found in-between individual lacunae is called what?
Interterritorial matrix
What are isogenous aggregates?
groups of 4-8 cells that originate from a single chondrocyte (also called nests)
<p>What are the two grow mechanisms of cartilage?</p>
<p>1-Appositional growth (perichondrium chondroblastsadd to existing cartilage) 2-Interstitial growth (proliferation and hypertrophy of existing chondrocytes)</p>
What is different about elastic cartilage?
matrix contains elastic fibers (more cells/matrix than hyaline cartilage)
What is different about fibrocartilage?
Matrix contains type I and type II collagen fibers (very little ground substance, mostly fiber) Pubic symphysis, intervertebral disks
What are the regions of mature bone made of?
Outer: compact/cortical bone
Interior: trabecular/spongy/cancellous bone
(these are microscopically identical)
What covers the outer surface of bone?
periosteum (attached by sharpey’s fibers)
What covers the interior surface of bone?
endosteum
what is on the end of long bones instead of periosteum?
articular cartilage
What are osteoblasts and osteoclasts derived from?
- bone forming osteoblasts: mesenchyme
- bone resorbing osteoclasts: monocytes
Once surrounded by bone matrix, what are osteoblasts?
osteocytes
What connects the extended processes of osteocytes in canaliculi?
gap junctions
What space is formed under osteoclasts?
howships lacunae
What are the main organic and inorganic components of bone matrix?
organic: Type I colagen, gags and proteoglycans
Inorganic: hydroxyapatite
What are the two processes by which bone is made?
Intramembranous (loose CT)
Endochondral (cartilage matrix)
What are the two steps of bone formation?
1-Primary bone/woven bone
2-secondary bone/lamellar bone
What is the bone surrounding haversians canals called?
osteons
What are the lateral connections between haversian canals called?
volkmanns canals
Growth in diameter of long bones is done by?
intramembranous ossification (also initiates bone formation in diaphysis)
Growth in length of long bones is done by?
endochondral ossification at the epiphyseal growth plate
What regulates bone growth at the epiphyseal growth plate?
Growth Hormones and chondroblast produced factors
Incorrect chondrocyte differentiation resulting in loss of articular cartilage can lead to what?
Osteoarthritis
