Histo Cartilage and Bone Flashcards
What does cartilage do?
1) provides shape and flexibility
2) shock absorber
3) facilitates smooth movements of joints
What is cartilage made up of?
CT,cells, ground substance, and fibers
What is cartilage typically surrounded by?
perichondrium
What doesnt cartilage contain that most other CT does have?
doesnt have blood vessels or nerves
How does cartilage get its nourishment?
via diffusion of gases and nutrients through ECM
Is cartilage prevalent in adults?
nope
Can cartilage grow rapidly?
Why is it important in the developing human?
yes :)
Bones of the skeleton are preceded by a temporary cartilage “model”
(blank) is also formed very early during the repair of bone fractures
cartilage
What sucks about adult cartilage?
it has poor access to nutrients which results in decreased water content and small cavities in matrix which leads to calcification and further compromised nutrition.
What are chondrocytes?
cells of cartilage
What is awesome about the lack of fanciness of cartilage?
it can be used in transplants without worry of antibodies or rejection
Are chondrocytes excellent at keeping pace with repair requirements after acute damage to hyaline or articular cartilage?
No, instead CT of fibrous cartilage picks up the slack and fills in the defect
What does articular cartilage (subset of hyaline cartilage) do?
facilitates movement at the ends of long bones
Whats cute about cartilages abilities?
it keeps our noses and ears warm :)))))
What kind of cartilage is important in utero because it is important for creating the models for all of our long bones?
hyaline cartilage
What is hyaline cartilage useful for?
resisting compression due to its super hydration
Does hyaline cartilage have a perichondrium?
Yes, except for in articular cartilage and epiphyseal plates
Where do we find elastic cartilage?
in things that bounce (ear, larynx, nose)
What is the most cellular cartilage?
elastic
Does elastic cartilage have a periochondrium? Does it undergo calcification?
yes
NO
What is fibrocartilage good for?
resists deformation under stress
What is significant about fibrocartilage?
it contains type I cartilage!!!!!
What type of cartilage is found here:
fetal skeletal tissue, epiphyseal plates, articular surface of synovial joints, costal cartilages of the rib cage, cartilages of the nasal cavity, larynx, rings of trachea and plates in the bronchi?
hyaline cartilage
What type of cartilage is found here:
intervertebral disks, pubis symphysis, articular disks, menisci, triangular fibrocartilage complex, instertion of tendons
fibrocartilage
What type of cartilage is found here:
pinna of external ear, external acoustic meatus, auditory tube, cartilages of larynx
Elastic cartilage
What type of cartilage functions to provide flexible support?
elastic cartilage
What type of cartilage functions in resisting deformation under stress?
fibrocartilage
What type of cartilage functions in resistin compression, providing cushioning, creates smooth and low friction surface for joints, structural support in respiratory system, forms foundation of development of fetal skeleton and further endochondral bone formation and bone growth?
hyaline cartilage
What type of cartilage does NOT have periochondrium?
fibrocartilage
What type of cartilage does NOT undero calcification?
elastic cartilage
What type of cartilage does not have both chondroblasts and chondrocytes?
fibrocartilage, it has chondrocytes and FIBROBLASTS (the other cartilages have just chondrocytes and chondroblasts)
What are the characteristics of the ECM of hyaline cartilage?
Type II collagen fibers
aggrecan
What are the characteristics of the ECM of elastic cartilage?
Type II collagen fibers and elastic fibers, aggrecan
What are the characteristics of the ECM of fibrocartilage?
type II and type I collagen fibers, versican, proteoglycan secreted by fibroblasts
(blank) is highly hydrated.
hyaline cartilage
Are the components of the hyaline matrix evenly distributed?
no
How do you know you are looking at cartilage or bone?
you will see cells in holes
In hyaline cartilage there are darker areas around chondrocytes, what are they?
What are the light spots?
territorial matrixes
interterritorial matrixes
In hyaline cartilage, chondrocytes will be grouped into (blank) groups which represent mitosis of these chondroblasts.
isogenous groups
What makes up the perichondrium?
an outter fibrous layer and an inner chondrogenic layer (made up of chondroblasts and chondroenic progenitor cells)
What is interstitial growth of cartilae?
the ability of chondroblasts to divide inside the cartilage and have the inside grow (made from isogenous group)
What is appositional growth?
growth on the outside of cartilage via chondroblasts
So what are the two ways cartilage can grow?
interstitially and apositionally
What is articular cartilage and what does it do?
it is a type of hyaline cartilage that transforms ends of bone into lubricated, wear proof and compressible surfaces that reduce friction
Does articular cartilage have a perichondrium or vascularization?
no
no
What are the zones that articular cartilage are divided into?
Outside towards bone
tangential layer-> transitional layer-> radial layer-> calcified cartilage
Describe the tangential layer of the articular cartilage
tangential layer-> small, flattened chondrocytes, superifical layer devoid of cells (lamina splendens).
very fine collagen fibers in matrix that run parallel to surface of cartilage.
Describe the transitional zone of the articular cartilage
large and round chondrocytes that occur singly and in isogenous groups. Collagen fibers take an oblique course through matrix of transitional zone
Describe the radial zone of the articular cartilae
fairly large chondrocytes form radial columns oriented perpendicular to the articulating surface, collagen fibers follow the course of the chondrocyte columns
Describe the calcified cartilage layer
it rests on the underlying cortex of the bone and stain darker than the matrix of the others
The important thing to take home is that bone and cartilage are (blank)
dynamic
In articular cartilage, any fibers that we find in the (blank) will run parallel to the surface. if we come down to the (blank) we will see that the cells as well as the fibers will run obliquely. The (blank) will have perpendicular columns of cells and fibers that reinforces (i.e for strength) the pounding that the articular surface is going to take.
tangential layer
transitional zone
radial layer
What will we see if we are looking at an H&E of elastic cartilage?
lots of cells, elastic fibers and occasionally some type II collagen fibers if they arents covered by the elastic fibers
Chondrocytes in (blank) retain a fairly high mitotic rate throughout life and this type of cartilage does not calcify
elastic cartilage
What is this:
a form of connective tissue transition between dense CT and hyaline cartilage.
fibrocartilage
Tell me about fibrocartilage
no perichondrium
parallel columns of chondrocytes
collagen type I
What part of the intervertebral disc is made up of fibrocartilage?
the anulus fibrosis
Where does all cartilage come from?
mesenchymal cells
What give rise to cartilage proper?
chondroblasts
What gives rise to the perichondrium (dense irregular CT)?
fibroblasts
What are the two types of growth that cartilage undergoes?
appositional growth
interstitial growth
What kind of growth is this:
Chondrogenic cells from inner layer of perichondrium become chondroblasts
In newly forming cartilage, the growth is mainly this.
appositional
In older cartilage what is growth mainly?
interstitial due to lack of chondrogenic cells
What is this:
Only growth that occurs in articular and fibrocartilage because both lack a perichondrium
Important for the growth of long bones at the epiphyseal plate.
interstitial growth
T or F
Cartilage has a very high ability for repair
F
Explain the histogenesis of hyaline cartilage
mesenchyme is precursor tissue-> mitotic proliferation-> chondroblasts separated by matrix formation-> multiplication of cartilage cell-> isogenous groups-> surrounded by territorial (capsular) matrix
(blank)is one of the hardest substances of the body, is the primary structural framework for support and protection of the organs of the body including the brain and spinal cord.
bone
What are the functions of the bone?
protection of internal organs support and movement hemopoiesis (red marrow) energy storage (yellow marrow-fat) mineral reservoir (99% body calcium)
What is the structure of bone?
ECM w/ organic and inorganic components and cells :)
What are the organic components of the ECM of bone?
(35% of bone matrix)
made by osteoblasts, type 1 collagen, proteoglycans (aggrecan), glycoproteins (osteocalcin, osteopontin,osteonectin)
What are the inorganic components of the ECM of bone?
(65%of bone matrix) hydroxyapatite crystals (calcium and phosphorus)
What happens to adults red marrow? When can this change?
it converts to yellow marrow to store fat
In cases of anemia or hemmorage (yellow can convert to red)
What are the cells of bone (5)?
osteoprogenitor osteoblasts osteocytes bone lining cells osteoclasts
(blank) cells are derived from mesenchymal cells
osteoprogenitor
(blank) develop from osteoprogenitor cells that line the inner periosteum, the endosteum, and lining the haversian canal. These synthesize the organic components of bone matrix; some gradually become surrounded by matrix and become osteocytes
osteoblasts
(blank) lie in a lacuna within the matrix; involved in exchange of nutrients and waste with blood via canaliculi.
osteocytes
(blank) are cells that remain on the bone surface when there is no active growth
bone lining cells
(blank) are derived from bone marrow precursor. They secrete enzymes and biochemically concentrate H+ ions to dissolve bone and calcium salt crystals thereby releasing minerals into blood.
osteoclasts
Do osteoclasts come from mesenchyme?
no they come from macrophage precursors (CFU-GM)
Describe the creation of bone cells.
mesenchymal cells-> osteoprogenitor cells (primordial germ cells)-> make all cells (cept for osteoclasts)-> osteoblasts-> osteocytes-> bone lining cells (periosteal cells).
Where will you find osteoblasts?
in periosteum and endosteium and canal.
The (blank) synthesizes all the organic components of the bone matrix and when they get surrounded by the bone matrix they become osteocytes
osteoblasts
how do osteocytic processes communicate?
via gap junctions and will form cannuliculi.
What do the cannuliculi of bone allow for?
exchange of nutrients and ridding of waste
Do bone lining cells add to interstital growth or appositional growth?
appositional growth
Where do the precursors of osteoclasts originate?
What do osteoclasts have on them?
in the bone marrow
receptors for hormones (including calcitonin)
What are large, motile, and multinucleated cells that contain up to 50 nuclei and have an acidophillic cytoplasm?
osteoclasts
osteoclasts occupy shallow depression called (blank)
howships lacunae (that identify regions of bone resorption)
What does PTH do?
targets osteoblats-> release osteoclast stimulating factor-> increases osteoclast activity-> increases calcium levels and breakdown of collagen via collagenase.
(blank) cells secrete calcitonin inhibiting resorption by osteoclasts.
parafollicular cells
Osteoclasts have a bone marrow precursor in common with (blank)
monocytes
Osteoclasts occupy shallow depressions called (blank). What do these identify?
howships lacunae
regions of bone resoprtion
How do you get bone resorption via osteoclasts?
osteoclasts meet up with bone, release lysosomal enzymes and hydrogen ions into microenvironment, takes out the calcium and phosphate from bone matrix and put into osteoclast cytoplasm and then transferred to blood
Where do we get collagenase?
from the amazing osteoblasts! They knew from the very beginning that one day their amazing creation of bone would have to go so they laid down collagenase in there!
Describe layers of bone, outside to in
periosteum-> compact bone-> endosteum-> spongy bone
What is this:
Bone is covered on its external surface (except at synovial articulations) with this.
periosteum
What does the periosteum consist of?
outer layer of dense fibrous CT and inner cellular layer containing osteoprogenitor (osteogenic) cells and periosteal cells
What is the endosteum?
The lining of the central cavity of the bone
What is the endosteum made up of?
a specialized thin CT composed of a monolayer of osteoprogenitor cells, osteoblast, and endosteal cells
Following injury, cells in the layers of the periosteum and endosteum do what?
they differentiate into osteoblasts to repair damaged bone
What are concentric lamallae?
they are the circlar rings of the osteon
What is an osteon?
they are numerous circular rings of osteocytes with a haversion canal in the center
Where will you see compact bone?
diaphysis of long bones
outer bone table of flat bones
What is this:
concentrically arranged lamella of bone surrounds canal containing capillaries
Haversion system or osteon
What are lacunae?
they are the little spaceships that the osteocytes sit in and hold hands with the other space ships via canaliculi
How do the osteocytic processes hold hands?
via canaliculi
What are the volkmann’s canal?
they are horizontal channels containing blood vessels from bone marrow and periosteum
What do the volkmanns canals do?
provide blood and interconnect haversian canals
What are the different kinds of lamallae?
1) inner, outer circumferential
2) interstitial
So what are all the things that a compact bone has?
osteon
volkmanns canal
lamallae (circumferential, interstitial)
periosteum, endosteum
What is special about the collagen fibers in lamellae?
they are oriented in different directions in each osteon to provide strength to compact bone
Cancellous, spongy or trabeculated bone is found within……?
long, short, flat, irregular bones
AND
in bone marrow of diaphysis epiphysis
What does cancellous, spongy or trabeculated bone have within it?
lamellae BUT NO OSTEONS!!!!
Tell me about Lamella?
there is an outter circumferential lamella that runs around the bone
There is an inner circumferential lamella that runs around the whole marrow cavity
There is an interstitial lamella that are between the osteons/haversions system
What do interstital lamella tell us?
that bone remodeling has occured
What are the processes of bone formation?
intramembranous bone formation and endochondral
What is intramembranous bone formation?
osteoblasts make bone in flat bones (direct mineralization)
What is endochondral bone formation?
deposition of bone matrix on a preexisting cartilage matrix
i.e. within cartilage
What is mature intramembranous bone?
spongy bone/trabecular bone
Most flat bones are formed by (blank)
intramembranous bone formation
What exactly is intramembranous bone formation?
it is the process of making bone from vascularized mesenchymal tissue that are a series of connected cells (long processes)
Mesenchymal cells differentiate into (blank) that secrete bone matrix.
osteoblasts
What is the structure of the bone matrix that osteoblasts create?
network of spicules and trabeculae with randomly oriented collagen fibers which make an osteoid
Explain briefly the creation of osteocytes.
mesenchyme-> osteoblasts-> osteoid and bone matrix-> solidification and creation of osteocytes
What quickly follows osteoid formation?
calcification, which traps osteoblasts and makes them become osteocytes
During the development of bone formation is there a time that the cells are not connected?
no, they are always connected even when they are fully mature
osteocytes retain their contacts which establishes a system of ….?
canaliculi
How does bone formation continue?
mitosis of mesenchyme makes osteoprogenitor cells which make osteoblasts
How do we make compact bone?
mesenchymal cells form periosteum and endosteum
What do osteoprogenitor cells from the periosteum and endosteum form?
the outer and inner plates of compact bone
What covers trabeculi of spongy bone?
endosteum
What is found in the endosteum?
osteoprogenitor cells, osteoblasts, and endosteal cells
Most of the long and short bones of the body develop by (blank)
endochondral bone formation
Bone is made from components of (blank)
cartilage
As soon as we vascularize long bone, the (blank) cells are released and thus we get bone formation.
osteoprogenitor
Bone formation depends on (blank)
hyaline cartilage model
What is the hyaline cartilage model>
it is the use of cartilages products to make bone
Explain how we get perichondtrium and osteoblasts in endochondral bone formation
you start with hyaline cartilage-> vascularization at diaphysis->chondrogenic cells become osteoprogenitor cells-> osteoblasts-> periochondrium becomes periosteum
What secretes bone matrix and allows for the formation of the subperiosteal bone collar by intramembranous bone formation?
osteoblasts
The (blank) within the core of the cartilage model die resulting in future marrow cavity
hypertrophied chondrocytes
Holes etched in the bone collar by osteoclasts permit a (blank) to enter the concavities within the cartilage model.
periosteal bud (osteogenic bud)
Osteoprogenitor cells divide to form (blank), producing bone matrix on the surface of the calcified cartilage.
osteoblasts
(blank) becomes thicker and grows in each direction from the midriff of the diaphysis toward the epiphyses.
subperiosteal bone
How do we get an enlarged marrow cavity?
osteoclasts baby
Where do primary ossification centers appear?
where do secondary ossification centers appear?
in the diaphysis
in the epiphysis
How do you get bones to grow in length?
interstitial growth of cartilage
How do you make bones grow in girth?
by appositional growth at the periosteum
New cartilage is formed on the epiphyseal side of the plate at the the same (blank) that new bone is formed on the diaphyseal side of the plate.
So what does this tell us?
rate
tells us that eiphyseal plate remains the same thickness, but the length of the diaphysis increases
What are the 5 zones of the epiphyseal plate?
resting zone proliferative zone hypertrophic cartilage zone calcified cartilage zone ossification zone
Chondrocytes become chondroblasts and undergo proliferation in the (blank)
proliferative zone
yeah, its weird that chondrocytes become chondroblasts
Describe the journey of a lowly chondrocyte
hangs out and gets its rest in the resting zone, then undergoes mitosis in the proliferation zone,undergoes hypetrophy in hypertrophic zone, undergoes calcification -> hits the ossification zone -> BOne
Is there appositional growht at the epiphyseal plate?
no
What is this: Fracture breaks blood vessels of bone and periosteum and endosteum causing bleeding and formation of a clot.
Hematoma Formation
What is this: soft, fibrous tissue produced as a hematoma is infilitrated by blood capillaries and fibroblasts.
granulation tissue
What infiltrates granulation tissue?
Where do they come from?
Macrophages (eat the blood clot), osteoclasts, and osteogenic cells
Periosteal and endosteal sides of the fracture
How long does it take for osteogneic cells to build up numbers?
48 hours
Describe healing of bone after a fracture
1) hematoma formation (blood clot)
2) Formation of granulation tissue (osteoclast, macrophages, osteogenic cells and increase blood flow)
3) Soft callus formation-> fibroblasts placing collagen
hard callus formation->
4) osteogenic cells turn into osteoblasts and form bony collar around callus (like a hard splint, takes 4-6 weeks)
5) Remodeling
Fibroblasts deposit collagen in granulation tissue, while some osteogenic cells become chondroblasts and produce patches of fibrocartilage called (blank)
soft callus tissue.
Osteogenic cells build and differentiate into osteoblasts that produce a (blank).
bony collar
The (blank) that acts as a temporary splint- cements to the dead bone around injury (takes 4 to 6 weeks). Need for immobilization during this period.
hard callus
The hard callus persists for (blank) as osteoclasts dissolve small fragments of bone. (blank) bridge the gap between the broken ends with spongy bone. This is subsequently remodeled into (blank). Usually leaves a thickening of the bone. In adults 80% strength at 3 months
3 to 4 months
osteoblasts
compact lamellar bone
(blank) is produced when osteoblasts produce osteoid rapidly which occurs initially in all fetal bones (but is later replaced by resilient lamellar bone).
woven bone
So what happens to your fetal bones initially?
you make woven bone via rapid osteoid formation
When do adults get woven bones?
after fractures or in pagets disease
Describe the structural of woven bone.
weak with small amount of collagen fibers that forms quickly
(blank) is an articular cartilage repair surgical technique that works by creating tiny fractures in the underlying bone. This causes new cartilage to develop from a so-called super-clot.
Microfracture surgery
Human bone mass peaks between ages ….?
20-30
What has happening at age 20-30 with your bones?
cancellous/spongy bone is turning over at a higher rate than cortical bone. (after this age you have decline in bone mass for both sexes)
What is the most common metaobolic disease of the bone?
osteoporosis
What is this:
a disease in which bone volume is DECREASED but the bone that is present is NORMALLY calcified?
osteoporosis
What can this cause: lots of glucocorticoids drop of estrogen hyperthyroidism hyperparathyroidism
osteoporosis
HOw do postemenopausal women get osteoporosis?
loss of estrogen-> increased osteoblasts-> increased bone loss
What are the first clinical signs of osteoporosis?
kyphosis (vertebral fractures), wrist and hip fractures.
What has very high concentrations of cancellous bone and thus are among the first bones to show signs of thinning and fracture?
vertebrae and epiphysis of the femur
