Lecture 8 Flashcards
list the 3 major classes of cartilage:
Hyaline
Elastic
Fibrocartilage
Differ based on their matrix
Functions of cartilage:
Compressible Resists distortion Absorbs shock in joints Reduces friction in movable joints. Necessary for endochondral bone growth. Involved in fracture repair.
What is it called if cartilage persists to the adult form?`
Neotony
Cartilage is found:
Part or all of the skeletal system
Cartilage FORMING cells
Chondroblasts
Cartilage MAINTENENCE cells
Chondrocytes
What is the extracellular matrix composed of:
Collagen fibers:
[type II collagen]-[type I in fibrocartilage]
Ground substance:
hyaluronan, chondroitin, keratin, glycosaminoglycans
Outer fibrous layer surrounding a mass of cartilage
Perichondrium
Chondrocytes are involved in:
Production of the collagen and proteoglycans in the matrix.
cartilage is vascular or avascular?
AVASCULAR
Chondroblasts
Lay down cartilage maTRIX AND BECOMES CHONDROCYTES
Chondrocytes
Maintain cartilage matrix
Lacunae
Pockets w/in matrix where the Chondroblasts and Chondrocytes are found
Hyaline cartilage characters:
- MOST COMMON type of cartilage
- avascular
- type II collagen
- surrounded by perichondrium
- translucent, bluish gray white
- solid but flexible
- Chondrocytes are often found in cell groups [d/t cell division]
- Growth patterns: Appositional And Interstitial
- mostly a support cartilage
- asso. W/ highly movable joints
Appositional growth
Growth that occurs by adding more material to the outside of existing material
Interstitial growth
Occurs by inserting additional material into existing substance—-only living tissue can do this
Articulate cartilage covered w/ perichondrium?
No perichondrium
Cartilage is avascular; is bone?
Nope, bone develops in regions of high O2 [ ]
Hyaline cartilage location:
Mammals: -External auditory meatus -Ears,nose -MovablE joint surface -Larynx -tracheal, bronchial cartilage -fetal long bone -articulate ends OTher vertebrates: -skeletal systems...
Fibrocartilage characters:
- Increased collagen in matrix
- Reduced cellularity compared to hyaline cartilage
- not surrounded by perichondrium
- opaque appearance from fibrous texture
- Type I collagen
- single sparse Chondrocytes
2 components of bone matrix:
Organic:osteoid- provides flexibility
Inorganic: hydroxyapatite 35-65% of the matrix
3 major types of bone:
Woven bone: occurs during bone development and repair.
Compact bone: lamellar bone
Spongy bone: trabecular or cancellous bone
General histology of compact bone.
Lacks cavities and forms dense plate on outside of long/flat bones.
Consists of concentric [haversian] lamellae which encircle a central blood vessel and nerves forming an osteon or haversian system.
Osteocytes found btw lamellae located in lacunae and are connected to each other and the Haversian canal via caniliculi
Volkmann’s canal run perpendicular to Haversian canals and connect the Haversian canals to each other and to the surface of the bone
Membrane Bone formation:
- bone is laid down in fibrous [collagen] CT matrix.
- osteoblasts use the collagen fibers as a framework to deposit bone matrix
- bone formed w/in the original mesenchyme has a spongy texture: spongy bone
- periosteum may form on either side of the spongy bone.
- periosteum will lay down layers of compact bone on top of the spongy bone (appositional growth)
- generally found in bones that form walls of cavities -cranial vault
- do not form complex articulations
- grow in appositional both diameter and thickness
Endochondral bone formation:
1-primary ossification center in future diaphysis of cartilage model.
2-Chondrocytes become hypertrophic
3-Chondrocytes secrete vascular endothelial growth factor
4-Blood vessels break through perichondrium bringing in osteoprgenitor cells
5-Hypertrophic cartilage cells undergo apoptosis, leaving behind thin strands of calcified matrix.
6-osteoclasts use calcified strands as substrates for deposition of osteoid.
7-osteoid is calcified.
Advantages of endochondral bone growth:
The bone can grow tall/wide and also repair.
