unit 5

Question 1

what is the origin of chondroblasts? where are they located?

Answer 1

paraxial mesoderm
located in the periphery

Question 2

what is chondrogenesis?

Answer 2

matrix producing during development and growth

Question 3

what is appositional tissue growth?

Answer 3

when chondroblasts secrete new matrix along existing surfaces, causes cartilage to expand and widen

Question 4

what is the origin of chondrocytes? where are they located?

Answer 4

chondroblast
central/deep location

Question 5

what are chondrocytes the primary cell for?

Answer 5

primary matrix producing cells within mature cartilage resulting in interstitial tissue growth

Question 6

what is interstitial growth?

Answer 6

chondrocytes secrete new matrix within the cartilage, grows the bone in length

Question 7

what is the composition of cartilage?

Answer 7

semi-solid, not highly organized with randomly dispersed cells
aggrecan-hyaluronan aggregates and cartilage-specific collagen molecules

Question 8

why is cartilage firm yet pliable?

Answer 8

due to interaction of GAGs and PGs

Question 9

what type of collagen molecules are found in cartilage?

Answer 9

type II collagen, and VI, IX, X, and XI

Question 10

why is a semi-solid composition in cartilage important?

Answer 10

crucial for diffusion of nutrients and waste

Question 11

cartilage is…

Answer 11

avascular and aneural

Question 12

what is a lacunar space?

Answer 12

void space in cartilage where a cell resides
located in the ECM, accommodate chondrocytes

Question 13

isogenic groups

Answer 13

regions where chondrocytes sit next to each other
represent cells that have recently divided

Question 14

capsular (pericellular) matrix

Answer 14

directly surrounds lacunae, stains darkest
high concentration of PGs, GAGs, MAPs

Question 15

territorial matrix

Answer 15

surrounds isogenic groups, stains in the middle

Question 16

interterritorial matrix

Answer 16

occupies space between IGGs, stains light

Question 17

what determines the intensity of cartilage matrices?

Answer 17

proximity of produced micromolecules

Question 18

where is hyaline cartilage found?

Answer 18

articular surfaces of synovial joints, costal cartilage, nasal cavity, larynx (thyroid, cricoid, arytenoid), trachea, bronchi, fetal skeletal tissue, epiphyseal plates

Question 19

where is fibrocartilage found?

Answer 19

IV discs, pubic symphysis, articular discs, menisci of knee, wrist joint, insertions of tendons

Question 20

where is elastic cartilage found?

Answer 20

pinna of external ear, external auditory meatus, auditory tube, larynx (epiglottis, corniculate, cuneiform)

Question 21

hyaline cartilage

Answer 21

most common, weakest
staining appears homologous

Question 22

what is hyaline cartilage surrounded by? what can it undergo?

Answer 22

perichondrium
calcification (endochondrial ossification at epiphyseal plate)

Question 23

what does type II collagen do for hyaline cartilage?

Answer 23

allows it to withstand pressure

Question 24

fibrocartilage

Answer 24

less cellular, less able to repair and regenerate, NO perichondrium
type I collagen

Question 25

why is type I collagen important in fibrocartilage?

Answer 25

helps with tension structure of collagen forces the chondrocytes into linear rays

Question 26

elastic cartilage

Answer 26

type II collagen, GAGs, PGs, GPs, elastic fibers, lamellae

Question 27

what is osteoarthritis?

Answer 27

mechanical breakdown of cartilage chondrocytes are worn away, the tissue loses the ability to retain water

Question 28

what is articular cartilage

Answer 28

hyaline cartilage covering a moveable joint more organized with NO perichondrium

Question 29

articular cartilage

Answer 29

Question 30

what is the origin of osteoblasts? where are they located?

Answer 30

mesoderm or ectoderm bone surface

Question 31

how do osteoblasts contribute to bone formation?

Answer 31

they cover themselves in osteoid which is then mineralized around them

Question 32

what is the origin of osteocytes? where are they located?

Answer 32

osteoblasts in lacunar spaces where matrix isn't ossified

Question 33

what allows for osteocytes to do mechanosensation?

Answer 33

fluid moving through lacunar-canalicular network

Question 34

what do lacunar-canalicular networks allow for?

Answer 34

communication between adjacent cells and free surface cells

Question 35

what is the origin of osteoclasts? where are they located?

Answer 35

lateral mesoderm bone surface

Question 36

what are osteoclasts?

Answer 36

bone macrophages, monocyte that left circulation to participate in bone resorption

Question 37

organic composition of bone

Answer 37

type I collagen, BMPs, CBPs, MAPs, ALP allows the bone to stretch to a point

Question 38

inorganic composition of bone

Answer 38

calcium phosphate forming hydroxyapatite crystals allows for compression resistance

Question 39

bone is...

Answer 39

vascular and neural arteries branch in central and perforating canals

Question 40

what do calcium binding proteins do?

Answer 40

bind extracellular Ca2+ which stimulates osteoblasts to secrete alkaline phosphatases

Question 41

what do alkaline phosphatases do?

Answer 41

increase local concentration of PO4 ions, further increases the Ca2+ concentration

Question 42

what do osteoblast ectosomes do?

Answer 42

accumulate Ca2+ and PO4, assemble hydroxyapatite crystals

Question 43

what do bone matrix proteins do?

Answer 43

contribute to formation of ECM collagen scaffold for mineral deposition

Question 44

what do hydroxyapatite crystals do after they exit the matrix vesicles?

Answer 44

develop as mineralized nodules within the ECM collagen scaffold

Question 45

what does the ruffled border of the osteoclast do?

Answer 45

increases SA, which in turn increases proton secretion and hydrolytic enzyme exocytosis

Question 46

what does increased proton secretion lead to?

Answer 46

decalcification

Question 47

what does increased hydrolytic enzyme exocytosis lead to?

Answer 47

collagen degradation by cathepsin K

Question 48

what is the clear zone?

Answer 48

tight seal between osteoclast plasma membrane and bone matrix, ensures mineralization is localized

Question 49

what is the basolateral region of the osteoclast for?

Answer 49

exocytosis of bone debris

Question 50

osteoporosis

Answer 50

imbalance in bone producing osteoblasts and bone resorbing osteoclasts bone resorption> bone formation

Question 51

what is an osteon?

Answer 51

function unit of bone

Question 52

bone organization

Answer 52

Question 53

how is bone classified?

Answer 53

by organization

Question 54

trabecular or cancellous bone

Answer 54

spinuols of bone

Question 55

compact bone

Answer 55

plate of bone

Question 56

endochondral ossification

Answer 56

mesoderm -> paraxial mesoderm -> somites -> cartilage -> bone most axial and appendicular bones

Question 57

endochondral ossification steps

Answer 57

cartilage model periosteal bony collar cartilage matrix mineralized blood vessel formation & periosteal migration cartilage matrix reabsorbed and replaced with bone matrix (most axial and appendicular skeleton) https://www.youtube.com/watch?v=YXDyQiVepWk

Question 58

intramembranous ossification

Answer 58

ectoderm --> neural crest --> mesenchyme --> bone flat bones of skull and face

Question 59

interstitial growth

Answer 59

cartilage resorption and bone deposition osteoclasts and osteoblasts work together

Question 60

appositional growth

Answer 60

uncoupled bone resorption and formation "bone modeling" osteoclasts and osteoblasts work independent

Question 61

what can cells in the zone of reserved cartilage do?

Answer 61

go through mitosis

Question 62

epiphyseal growth plate layers

Answer 62

zone of reserved cartilage zone of proliferation zone of hypertrophy zone of calcified cartilage zone of resorption (primary spongiosa)

Question 63

how can bone remodeling be described?

Answer 63

stochastic (random) or targeted

Question 64

stochastic bone remodeling

Answer 64

osteoblast actives -> osteoclast resorbs -> osteoblast forms

Question 65

targeted bone remodeling

Answer 65

repair microcracks osteoclasts bore a hole in bone to get to crack, form a cutting cone, osteoblasts form bone

Question 66

what does bone maintenance require?

Answer 66

mechanical stimulation

Question 67

woven bone formation

Answer 67

osteoblasts can't keep up with the demand so osteoid is laid down in an unorganized manner

Question 68

when are osteoblasts and osteoclasts equal

Answer 68

in bone maintenance

Question 69

when are there more osteoblasts than clasts?

Answer 69

bone formation, woven bone formation

Question 70

when are there more osteoclasts than blasts?

Answer 70

disuse bone loss

Question 71

calcium regulation via PTH

Answer 71

Question 72

how is a bone fracture healed?

Answer 72