HISTO: Cartilage, Bone Flashcards
What is a general characteristic of cartilage
- abundant ECM o type 2 fibrils
- no vascular
- GAGs
What is function of cartilage
mechanical stress, diffusion, weight, shock absorber, model for bone
types of cartilage:
hyaline, elastic, fibrocartilage
characteristic of hyaline cartilage
matrix containing type II collagen fibers
elastic cartilage characteristic
elastic fibers and lamellae in addition to hyaline
fibrocartilage charateristic
abundant type I collagen fibers in addition to hyaline
hyaline collagen matrix is synthesized by
chondrocytes
types of molecules that make hyaline cartilage matrix
collagen
proteoglycans
multiadhesive glycoproteins
which collagen fibers are used in hyaline cartilage
type 2**
type 9, 11
type 6, 10
which proteoglycans are found in hyaline cartilage
GAGs:
AGGRECAN
hyaluronan
chondroitin sulfate
The most important proteoglycan monomer in hyaline cartilage is
aggrecan - water affinity
which multiadhesive proteins are found in hyaline cartilage
anchorin CII - collagen receptor on chondrocytes
fibronectin and tenascin - anchor chondrocytes to matrix
chondrocytes function:
produce and maintain the extracellular matrix
cell line from mesenchymal cell in cartilage:
growing cartilage - chondroblast - chondrocytes
function of chondroblast
secrete ecm and form lacuna
chondrocytes secrete:
matrix and MMP (degrades matrix) proteoglycans
what is an insterstitial growth - isogenous group
mitotic activity
what TF triggers cell differentiation into chondroblasts which secrete matrix
SOX-9
what are the types of cartilage growth
appositional and interstitial
3 components layers of hyaline cartilage matrix
intrterritorial matrix - fibrils
territorial matrix - collagen 2, 9, protegylcans
capsular matrix - proteoglycans, collagen 6, 9
which type cartilage forms model of skeleton in fetus
hyaline cartilage as growth plstes
what type of hyaline cartilage is in adults
articular cartilage - synovial and costal, nasal, bronchi, larynx
why is hyaline cartilage highly hydrated
resilience and diffusion of small metabolites
how can cartilage repair occur
if perichondrium is involved, type I collagen
Cartilage at the proximal and distal end of the bone serves as growth sites called
epipheseal growth plates
Hyaline cartilage of articular joint surfaces do not posses
perichondrium
Degenerative joint disease related to aging
ostheoarthritis
what plays important part in ostheoarthritis
chondrocytes: produce interleukin-1 and tumor necrosis factor a, so type II colagen is inhibited
is a more severe form where the immune system attacks the cartilage, bone and synovial membrane
rheumatoid arthritis
what does elastic cartilage form
auricles, auditory tube larynx
elastic cartilage differs from hyalin because
larger chondrocytes, yellowish, does not calcifty, less matrix
Elastic cartilage is distinguished by the presence of
elastin in cartilage matrix
which cartilage need specialized tint to view
elastic cartilage
what does fibrocartilafe form
IV discs, symphisis pubis, knee joint
what is fibrocartilage composed of
dense regular connective tissue and hyaline cartilage
what makes fibrocartilage different than hyaline and elastic
no perichondrium present
what type of collagen is fibrocartilage
type I mainly and type II
in older age. fibrocartilage is mostly collagen type:
II because of metabolic activity of chondrocytes
a proteoglycan monomer secreted by fibroblasts in fibrocartilage
versican
more than aggrecan (hyaline)
IV disc degeneration is associated with:
proteolytic degradation of proteoglycan aggregates
what collagen in tumor is associated with good prognosis
type 2 and 10
what collagen in tumor is associated with poor prognosis
type I
what can affect hyaline cartilage
hormones and vitamins a, c, d
what is bone (special ct) characterized by
mineralized matrix
mineralized matrix is made of
calcium phosphate in the form of hydroxyapatite crystals
to visualize organic component study technique
decalcified
to visualize inorganic component study technique
ground bone - undecalcified
secreted by osteoblasts
extracellular matrix and osteoid
major fibers of bone
collagen type I
disease of collagen type I in bone
osteogenesis imperfecta - brittle bones
multiadhesive glycoproteins of bone include:
osteonectin, osteopontin and sialoproteins
Bone-specific vitamin K- dependent proteins:
osteocalcin
protein s
Gla-proteins - vascular calcification
bone growth factors and cytokines include:
IGFs, TNF-a, TGF-b, BMPs, ILs
used clinically to induce bone growth after bone surgery involving large bone defects, spinal fusions, or implantation of graft materials
BMP-7 = OP-1
bone matrix contains ___ connected by canaliculi
lacunae
small tunnels extended by osteocytes
canaliculi
osteocyte processes communicate by
gap junctions
bone cell types:
osteoprogenitors - osteoblast - osteocyte - bone lining - osteoclast
osteoctyes are used for
intramembranous ossification
bone tissue is classified by
spongy cancellous or compact dense
bone coverings include
periosteum
endosteum
growth of bone tissue is
appositional
Mature bone is composed of structural units called
osteons (Haversian system)
lateral canal in bones
Volkmann’s canals
The matrix in immature woven bone stains more intensely with
hematoxylin
markers of osteoblastic activity
TNAP and osteocalcin
responsible for the calcification of the bone matrix
osteoblast
true or false: the majority of osteoblasts undergo apoptosis
true
released from the osteoblast at the osteoblast–osteoid interface
matrix vesicles
what forms hydroxyapatite crystals
Ca2+ and PO4
current concept of osteocytic remodeling is that the osteocyte is responsible for
calcium and phosphate ion homeostasis
osteocyte functional states:
quiescent - few rer and m
formative - more rer and golgi
resorptive - rer, golgi, m and l
part of the Mononuclear Phagocytic System
osteoclast
responsible for bone resorption
osteoclast
essential for osteoclast differentiation and maturation
RANK and rank ligand RANKL
Osteoclasts when actively resorbing bone, exhibit 3 specialized regions
ruffled border, clear zone, basolateral region
the most important regulator of calcium and phosphate levels in the extracellular fluid
PTH parathyroid hormone
what is the function of PTH?
-increases bone mass in osteocytes and osteoblast CAMP
-increase RANKL causing osteoporisis
what does estrogen and OPG suppress?
cytokines RANKL production by T lymphocytes
reduces osteoclastic activity
calcitonin
marker for osteoclastic activity
TRAP
causes osteopetrosis, a congenital disease bone mass - defective osteoclast function
less cathepsin K, carbonic anhydrase II
characterized by progressive loss of normal bone density accompanied by the deterioration of its microarchitecture
osteoporosis
what initiates intramembranous ossification
mesenchymal condensation - week 8
mesenchyme bone cells differentiate into
osteoprogenitor cells and CBFA1 TF
plays a role in fracture repair
intramembranous ossification
what parts interconnect with each other and form trabeculae in Intramembranous ossification
bone spicules
how does endochondral ossification begin
by 12th week FGFs and BMPs
first signs of ossification
bony collar
chondrocytes in the midregion become hypertrophic and synthesize
alkaline phosphatase
This first site when bone begins to form in the dyaphysis of a long bone is
primary ossification center
develops in the proximal epiphysis
secondary ossification center
Hyaline cartilage persists between the two epiphyses as
epiphyseal plate
cartilage is replaced by
bone
Growth in length of long bones depends on the presence of the
epiphyseal plates
epiphyseal plate zones (5):
reserve cartilage - resting
proliferation
hypertrophy - mature VEGF
calcified cartilage
resorption - spicules
The initial response to the bone injury produces a
fracture hematoma
what fills the gap at the fracture site producing a soft callus
fibrocartilage
what forms after bone necrosis in a fracture
soft callus which is then calcified into hard callus
