meneghini 2

Question 1

what are the cells in the cartilage that synthesize the ECM?

Answer 1

chondrocytes

Question 2

the ECM is made of?

Answer 2

GAGs and collagen fibers
it is the way to give nutrients and supply from the connective tissue to the avascular cartilage

Question 3

3 types of cartilage

Answer 3

hyaline
fibrous
elastic

Question 4

which type of cartilage induces the lubrification of synovial joints?

Answer 4

HYALINE CARTILAGE

Question 5

Which type of collagen is the most abundant in hyaline cartilage?

Answer 5

type II collagen, it is the bulk of collagen fibers and help the cartilage to resist to intermittent pressures

Question 6

proteoglycans structure

Answer 6

protein core+GAGs

Question 7

what are the GAGs present in hyaline cartilage?

Answer 7

chondroitin sulfate and keratan sulfate

Question 8

each GAG is composed of

Answer 8

long polymers of repeated disaccharide units made of
1 modified sugar (glucosamine or galactosamine)
1 uronic acid (glucoronate or iduronate)

Question 9

what is the most abundant proteoglycan in hyaline cartilage?

Answer 9

-aggrecan

Question 10

structure of aggrecan

Answer 10

100 chondroitin sulfate + 60 keratan sulfate+protein core
the negatively charged sulfate group of the GAGs have high affinity for water

Question 11

hyaluronic acid

Answer 11

-GAG present in the hyaline cartilage
-bonded to aggrecan (proteoglycan aggregate)
-doesn’t form proteoglycans
-made of repeated disaccharide units of glucosamine and glucoronate

Question 12

multiadhesive glycoproteins

Answer 12

-allow the interaction of the ECM with the cell surface
-mediate the interaction of collagen fibrils with proteoglycan aggregate

Question 13

anchorin CII

Answer 13

multiadhesive glycoprotein
acts as a collagen receptor on chondrocytes to link collagen fibers to the cells

Question 14

tenascin and fibronectin

Answer 14

allow the interaction between membrane receptors on chondrocytes and collagen fibers
-a sort of a bridge

Question 15

characteristics of young chondrocytes

Answer 15

-basophilic nuclei
-pale cytoplasm due to large golgi
-large ER for protein synthsesis
-metabilically active in modeling the cartilage ECM
-present lipid droplets and glycogen storage

Question 16

characteristics of old chondrocytes

Answer 16

-less metabolical active
-less basophilic nuclei and smaller golgi

Question 17

what’s the name of the dense connective tissue that sorrund the hyaline cartilage?

Answer 17

perichondrium

Question 18

can we have more than one chondrocyte in each lacuna?

Answer 18

yes
2 or 4 is frequent
–>its called isogenous group
are cells that have just divided

Question 19

different regions of the matrix within hyaline cartilage

Answer 19

-capsular matrix
rich in proteoglycans
rich in collagen type VI
-territorial matrix
-less purple
-rich in collagen type II
interterritorial matrix
-less stained->less proteoglycan
aged cartilage

Question 20

what can we find in the perichondrium?

Answer 20

-fibroblast that produce type I collagen
-chondrocytes progenitors that give rise to chondroblasts
-all the nutrients and the nervous signals that are needed for the correct function and for the survival of chondrocytes are in the perichondrium

Question 21

cartilage can grow in 2 ways

Answer 21

-appositional growth
chondrocytes progenitors in the perichondrium become chondroblasts that syntehtise collagen II molecules. when completely embedded in collagen matrix they become chodnrocytes
-interstitial growth
within the already existing cartilage
chondrocytes proliferate and synthesize new ECM

Question 22

what is absent in articular hyaline cartilage that is present usually in hyaline cartilage?

Answer 22

the perichondrium
->no chondrocyte progenitors
no new chondroblasts
no repair after damage of the tissue

Question 23

3 zones of articular hyaline cartilage

Answer 23

superficial zone
in contact w synovial fluid
flattened chondrocytes
compact collagen type II fibers to sustain the pressure of the synovial fluid
intermediate zone
rounded chondrocytes
sparse
less organized fibers
similar to normal hyaline cartilage

deep zone
chondrocytes form sort of columns

Question 24

elastic cartilage structure

Answer 24

similar as hyaline cartilage
-chondroblasts /chondocytes
-type II collagen
-aggrecan
-contains elastic fibers made of elastin
-can’t undergo calcification during aging
-present the perichondrium

Question 25

fibrocartilage structure

Answer 25

-chondrocytes arranged in lines or isogenous groups inside lacunae->secrete type II collagen -fibroblasts are present and produce type I collagen which makes this type of cartilage more resistant to compression ->shock absorber -fibroblast generate versican (proteoglycan made of less chondroitin sulfate) -no perichondrium -can undergo calcification

Question 26

the perichondrium is present in which types of cartilage

Answer 26

hyaline (no articular hyaline) elastic cartilage

Question 27

in which types of cartilages is the perichondrium absent?

Answer 27

articular hyaline cartilage and fibrocartilage

Question 28

in which types of cartilages can calcification occur?

Answer 28

hyaline and fibrocartilage

Question 29

in the diaphysis is more present compact or trabecular bone?

Answer 29

compact bone

Question 30

what surrounds the external compact bone?

Answer 30

the periosteum

Question 31

where is the marrow cavity present ?

Answer 31

in the diaphysis

Question 32

is more present compact or trabecular bone in the epiphysis?

Answer 32

trabecular

Question 33

metaphysis

Answer 33

between each epiphysis and the diaphysial shaft

Question 34

types of collagen in bone

Answer 34

type I and type V

Question 35

what is that makes the bone matrix more compact compared to cartilage?

Answer 35

the presence of hydroxyapatite crystals

Question 36

OSTEONECTIN

Answer 36

multiadhesive glycoprotein mediate attachment of hydroxyapatite crystal with collagen

Question 37

OSTEOPONTIN

Answer 37

multiadhesive glycoprotein mediate attachment of cells to the bone matrix

Question 38

OSTEOCALCIN

Answer 38

protein that regulate blood calcium levels can uptake calcium from the circulation

Question 39

RUNX2

Answer 39

transcription factor that allows osteoprogenitor cells to differentiate into osteoblasts

Question 40

osteoid

Answer 40

initial non mineralized matrix produced by osteoblasts made of collagen type I and organic matrix protein

Question 41

shape of inactive osteoblasts

Answer 41

flattened with elongated nuclei

Question 42

shape of active osteoblasts

Answer 42

round and basophilic

Question 43

passive bone mineralization 3 stages

Answer 43

1. precipitation of salts 2. nucleation 3. crystallization

Question 44

active bone mineralization

Answer 44

-happens in the osteoid mediated by the matrix vescicles of osteoblasts that contain a lot of phosphate and calcium (thanks to active transports and specific enzymes) ->first crystal, calcium ortophosphate is formed the crystal goes out from the vesicle into the osteoid and into the matrix. in the matrix we have a lot of calcium thanks to calcitonin and this calcium adds to the orthophosphate and there is the formation of hydroxyapatite crystal ->main component of mineralized matrix

Question 45

thanks to what the osteocytes can go in direct contact with blood vessels?

Answer 45

canalicoli

Question 46

osteocytes can be in 3 different states

Answer 46

quiescent formative-metabolically active-release matrix molecules resorptive->lysis of the matrix, release of calcium and phosphate in the blood for calcium and phosphate homeostasis

Question 47

main cells that regulate the process of bone degradation

Answer 47

osteoclasts derive from hematopoietic stem cells large, multinucleated reside in hownship lacunae

Question 48

what's the name of the canal that we have at the center of the osteon?

Answer 48

Haversian, contains blood vessels and nerves

Question 49

what connects the different Haversian canals?

Answer 49

Volkmann's canal

Question 50

osteoporosis

Answer 50

mutation affecting osteoblasts no bone apposition only resorption weak bones

Question 51

osteopetrosis

Answer 51

-mutation affecting osteoclast -irregular bone growth, no bone resorption