Cartilage Flashcards
Characteristics of cartilage:
-avascular
-no nerve supply or lymphatics
-extracellular matrix
What are the cells of cartilage?
chondroblasts or chondrocytes
What are the functions of cartilage?
-bear mechanical stresses without distortion
-shock absorber
-frictionless movement at joints
-bone repair
-fracture repair
What the three types of cartilage?
hyaline
elastic
fibrocartilage
What is perichondrium?
dense connective tissue interface around hyaline and elastic cartilage
-carry blood supply
-source of new cartilage cells
What are fibrogenic cells?
outer perichondrium, become fibroblasts and give rise to fibers and ground substance
What are chondrogenic cells?
inner perichondrium, give rise to chondroblasts and osteoprogenitor cells
When are chondroblasts formed?
when there is not high amounts of oxygen
When are osteoprogenitors formed?
where there is oxygen present
What are chondroblasts?
replicating cells that secrete cartilaginous extracellular matrix
-flatter cells with large nucleus
What are chondrocytes?
round cells with small, dark nuclei
-often in groups of 2-8 cells (isogenous groups)
What are chondroclasts?
cells in cartilage that is removing calcified cartilage
-appear to enter cartilage with vasculature
What does the matrix of cartilage do?
resist compressive forces
What are the components of cartilage matrix?
fibers (collagen) and GAGs
What are proteoglycans?
core proteins with GAG side chains
What is the most abundant monomer of GAGs in proteoglycans?
aggrecan
What causes the gel like consistency of matrix of cartilage?
electrostatic bonds between collagen fibers and GAG side chains
-bind of water to GAGs
What attach matrix components to one another?
glycoproteins
What are the glycoproteins associated with matrix?
link proteins, fibronectin, and chondronectin
What do chondronectin bind to?
C-4 and C-6 sulfates , HA and integrins
What is the territorial matrix?
matrix found around each chondrocytes
-high amounts of GAGs and low collagen
What is the inter-territorial matrix?
surrounds the territorial matrix
-more collagen II, fewer proteoglycans
What forms the consistency of hyaline cartilage?
extensive cross linkinh
What do proteoglycans associate with in hyaline cartilage?
collagen II fibrils
What surrounds hyaline cartilage? (except for in articular surfaces)
surrounded and nourished by perichondrium
Where is hyaline cartilage?
-temporary skeleton in embryo
-epiphyseal plates
What causes growth of hyaline cartilage?
hormones
What causes abnormal growth and calcification of hyaline cartilage?
hormones and vitamins
What is a characteristic of elastic cartilage?
increased flexibility
-returns to original shape after deformation
Where is elastic cartilage found?
auricle, auditory tube, ear, epiglottis, and laryngeal cartilages
Characteristics of fibrocartilage:
-no perichondrium
-chondrocytes in rows
-abundant collagen I and II
-ground substance has dermatan and chondroitin sulfate
Where is fibrocartilage found?
ligaments, articular surfaces, symphysis pubis, menisci, labrum, intervertebral discs
What can form due to damage in hyaline cartilage?
fibrocartilage
What is appositional growth?
new cartilage forming on surfaces of pre-existing cartilage
Where does appositional growth occur?
inner layer of perichondrium
What do chondrogenic cells make?
collagen I (in perichondrium)
What do chondroblasts secrete?
collagen II and ground substance
What are the stages of interstitial growth?
take place within cartilage mass itself
-chondrocytes divide within lacunae (make more isogenous groups)
-chondrocytes secrete more matrix, which increase mass of cartilage
-overall growth due to secretion of new matrix
What limits interstitial growth?
avascular nature
What typically repairs damaged cartilage?
perichondrium
Are a lot of chondrocytes produced in adulthood?
no, few are produced
What replaces cartilage?
dense connective tissue or bone (if vascularized)
What stimulates bone growth instead of cartilage repair?
proximity of blood vessels
