Osteochondrogenesis/ joint components Flashcards
bone histogenesis occurs by
intramembranous and endochondral bone formation
Both intramembranous and endochondral bone formation produce bone that appears
histologically identical
Bone formation is accompanied by
bone resorbtion
Bone remodeling is defined as
the combination of bone formation and resorbtion
how long does bone remodeling occur?
remodeling occurs throughout life
Ca++ concentration of body fluids controlled within
narrow limits
Bone is a ______ for Ca
buffer
Old osteons are constantly being
replaced
Osteoclasts form an
erosion tunnel
Remodeling occurs inside
compact bone and at bone surfaces
When new bone is laid down on an eroded surface, a thin layer of _________________ is first produced
cementing substance is first produced
The first layer produced when new bone is laid down on an eroded surface is called
“cementing or reversal line”
About what percentage of bone turns over each year in adults
10%
In flat bone formation, (intramembranous bone formation) mesenchymal cells condense into
primary ossification centers
When mesenchymal cells condense into primary ossification centers-differentiate into osteoblasts they begin secreting
osteoid collagen
Osteoid collagen has
randomly oriented collagen fibrils and the first bone formed from this is called woven bone
With calcification osteoblasts trapped in matrix become
osteocytes
Small spicules of developing bone unite to form
trabeculae
fusion of bony trabeculae produces a
spongy bone
in spongy bone blood vessels invade and other mesenchymal cells give rise to the
bone marrow
areas of mesenchymal tissue that do not undergo ossification differentiate into the
periosteum and endosteum
The woven bone initially formed from an irregular osteoid collagen matrix will convert to
lamellar bone in the outer layers and inner layer remains as spongy bone (dipole)
in endochondral bone formation hyaline serves as a
small model for the bone and as a scaffold for bone development
bone follows _________ (endochondral bone formation)
cartilage
2 stages for endochonral bone formation
development of primary and secondary centers of ossification
primary center of ossification develops at
the midriff of the diaphysis of the cartilaginous model
vascularization of the perichondrium at the primary ossification site transforms chondrogenic cells to
osteoprogenitor cells
after chondrogenic cells are transformed into osteoprogenitor cells they then differentiate into__________ and perichondrium is now called _________
osteoblasts
periosteum
role of osteoblasts on the surface of the cartilaginous model by intramembranous bone formation
osteoblasts produce the subperiosteal bone collar(deep to periosteum)
In ossification, the cartilage matrix in the diaphysis will eventually begin to
CALCIFY
the calcified cartilage matrix inhibits
nutrient diffusion and hypertrophied chondrocytes die
chondrocytes in the primary ossification center become________, and secrete _________ and _________
chondrocytes in the primary ossification center become hypertrophic, and secrete collagen X and vascular endothelial growth factor
in the bone collar osteoclasts create
perforations
role of the perforations in the bone collar created by osteoclasts
permit periosteal buds to enter the primitive marrow cavity in the C-model
periosteal buds (NAME some)
blood vessels, osteoprogenitor cells, and mesenchymal cells
the perforations of osteoclasts cause the walls of these newly created little spaces to be
calcified
in primary ossification, the subperiosteal bone collar thickens and elongates toward the
epiphysis
osteoclasts begin to resorb the calcified cartilage-calcified bone complex which… (primary ossification)
enlarges the primitive marrow cavity
calcified cartilage stains
basophilic
calcified bone stains
acidophilic
Bone matrix(osteoid) made and calcified on the surface of calcified cartilage forms a ________ __________-________ _________ complex
calcified cartilage-calcified bone complex
repetition of the sequence of events involved in primary ossification results in
bone formation spreading toward the epiphyses
Where do secondary ossification centers develop bruh????????????????????????????????????
epiphyses
secondary ossification centers develop at epiphyses after
diaphyseal ossification center is well established
Lauren London or Sanaa Lathan or Scarlett J or the new Yeezys
all of the above
secondary ossification begins when osteoprogenitor cells
invade the epiphyses and differentiate into osteoblasts
These make bone matrix and replace disintegrating cartilage
osteoblasts
when the epiphyses are filled with bone tissue, cartilage is found in what 2 areas
articular surfaces and the epiphyseal plates
articular cartilage remains and thus….
does not contribute to bone formation
Epiphyseal plates
Epiphyseal plates continue to grow- add new cartilage to epiphyseal end while being replaced at diaphyseal end
Diaphyseal and epiphyseal bone become continuous around age __
20
this signals the beginning of a secondary ossification center
penetration of blood vessels into the epiphysis from the perichondrium
Zone of reserve
small, randomly arranged, inactive chondrocytes
Zone of proliferation (interstitial growth)
region of rapid mitotic divisions, gives rise to row of isogenous cell groups
In the region of calcified cartilage, blood vessels penetrate the region and bring…
osteoprogenitor cells and begin the process of remodeling calcified cartilage into bone
region where the chondrocytes are enlarged
zone of cell hypertrophy and maturation
region where remnants of cartilage matrices become calcified and chondrocytes die
zone of calcification
zone where bone is made upon the calcified cartage, followed by the resorbtion of the calcified bone-calcified cartilage complex
Zone of ossification
periosteal buds penetrate_________ _____ and (does what)
periosteal buds penetrate epiphyseal cartilage and erode away the calcified cartilage
Epiphysis enlarges by ________ growth and ______ replacement
Epiphysis enlarges by cartilage growth and bone replacement
Bone is added to the outer layers of the diaphysis by what type of growth?
appositional growth
inactivated during puberty by estrogen
growth plate
Proliferating chondrocytes secrete _______________ which stimulates
Proliferating chondrocytes secrete Indian hedgehog protein(Ihh) which stimulates chondrogenic periosteal cells to secrete parathyroid hormone-related protein
PTH-RP stimulates______________ to divide but also inhibits ____________________
PTH-RP stimulates reserve zone chondrocytes to divide but also inhibits proliferative zone chondrocyte hypertrophy
Hypertrophic zone chondrocytes secrete
type X collagen and VEGF
Why you always lying?
OMG! sToP
Bone fracture damages _______, _________, and __________
bone fractures damage bone matrix, bone cells and blood vessels
bone fractures damage bone matrix, bone cells and blood vessels AND are usually accompanied by
localized hemorrhaging and blood clot formation
collar of callus forms where (basic)
A callus forms both internally and externally at the fracture site
In bone repair, endochondral bone formation replaces the cartilage with
primary woven bone
irregularly arranged trabecular of primary bone join the ends of fracture bone, forming a ____ ______
bony callus
hairline fractures heal via
intramembranous bone formation that occurs at the periosteal surface
The primary bone is resorped and replaced with _______________ as the fracture heals
The primary bone is resorted and replaced with secondary (lamellar) bone as the fracture heals
immovable joints composed of CT, cartilage, or bone. (unite the first rib to the sternum and connect skull bones)
Synarthroses
Amphiarthroses
slight movement. IV Disks
this type of joint is also called synovial joint
Diarthroses
Diarthroses permit _______ ______ and unite
Diarthroses permit maximum movement and unite long bones
Diarthroses joints are surrounded by a _______ ______ and these joints also contain
2-layered capsule
synovial fluid
colorless, viscous fluid rich in hyaluronic acid and proteins
synovial fluid
Bone repair involves proliferation of ____________ cells from the periosteum and endosteum surrounding the fracture
Bone repair involves proliferation of osteprogenitor cells from the periosteum and endosteum surrounding the fracture
Two layers of Diarthroses joint
1) External (fibrous) capsular layer
2) Internal (synovial) capsular layer - synovial membrane
the external layer of the diarthroses joint is basically a
fibrous layer of dense connective tissue
the internal (synovial) layer of the diarthroses is lined with what type of epithelium
Lined squamous to cuboidal cells on the internal surface
Layer of Diarthroses that contains Type A cells and Type B cells
Internal (synovial) capsular layer - synovial membrane
type B cells in the internal capsular layer of diarthroses resemble fibroblasts and probably secrete
synovial fluid
Nutrients in diarthroses joints diffuse to hyaline cartilage from
synovial fluid
disease characterized by abnormal osteoclast function where bones are brittle and break easily. Marrow cavity is not developed
Osteopetrosis
Deficiency in carbonic anhydrase II - osteoclasts can’t accumulate H+ in Howship lacunae to activate acid requiring lysosomal enzymes
Albers-Schonberg disease (marble bone disease)
Osteoporosis
loss of bone mass. postmenopausal osteoporosis mainly has normal rate of resorbtion, but decreased bone formation
Rheumatoid arthritis starts as an
inflammatory reaction in synovial tissue
Pathogenesis of Rheumatoid arthritis involves what unique cells
involves activation of CD4+ T cells
T cells produce IL-15 which stimulates
synovial macrophages to produce proinflammatory cytokines and metalloproteases
