Bone Cells, Cartilage & Function

Question 1

What type of connective tissue is bone?

Answer 1

Hard

Question 2

What are the functions of bone?

Answer 2

Support body (skeleton)

Muscle attachment (via tendons)

Protection of internal organs

Haematopoiesis (bone marrow)

Mineral homeostasis

Question 3

What does bone generally consist of?

Answer 3

Cells

Matrix (organic)

Mineral (inorganic)

Question 4

How much of bone is mineral?

Answer 4

75%

Question 5

How much of bone is organic matrix?

Answer 5

25%

Question 6

What is bone matrix made up of (and give percentages)?

Answer 6

Collagen type I - 90%

Non-collagenous proteins - 5%

Water - 5%

Question 7

What non-collagenous proteins are present in bone matrix?

Answer 7

Osteocalcin

Osteopontin

Bone sialoprotein

GAGs

Question 8

What is the mineral component of bone made up of?

Answer 8

Hydroxyapatite

Question 9

How many bones are in a typical adult body?

Answer 9

206

Question 10

What shape are osteoblasts?

Answer 10

Cuboidal

Question 11

Where do osteoblasts sit?

Answer 11

On bone surface

Question 12

What do osteoblasts do?

Answer 12

Synthesise osteoid/bone matrix

Question 13

What do osteoblasts contain a lot of and why?

Answer 13

RER and Golgi apparatus

Synthesis of collagen type I

Question 14

What cell junctions are present between osteoblasts?

Answer 14

Gap junctions

Question 15

What are osteocytes?

Answer 15

Terminally differentiated osteoblasts

Surrounded by bone matrix

Question 16

How long do osteocytes live for?

Answer 16

25 years

Question 17

Where are osteocytes found (sitting in)?

Answer 17

Osteocyte lacunae

Question 18

How are osteocytes connected?

Answer 18

Canaliculi (gap junctions)

Question 19

What do lining cells do?

Answer 19

“Resting” and may be reactivated to become osteoblasts

Line bone

Question 20

What are osteoprogenitor cells?

Answer 20

Osteoblast precursors

Question 21

Where are osteoprogenitors found?

Answer 21

Above osteoblasts in periosteum

Question 22

What are osteoclasts?

Answer 22

Bone-resorbing cells

Question 23

Where are osteoclasts found (sitting in)?

Answer 23

Howship’s lacunae

Question 24

How would you distinguish an osteoclast on a slide?

Answer 24

Large, multinucleated

Question 25

What allows attachment of an osteoclast to bone?

Answer 25

Sealing/clear zone

Question 26

What is the ruffled border of an osteoclast for?

Answer 26

Increase surface area for proton and chloride channels for mineral acidification

Question 27

What are the two stem cells of bone cells?

Answer 27

Mesenchymal stem cells = all except osteoclasts Haematopoietic stem cells = osteoclasts

Question 28

What cells are most abundant in cartilage?

Answer 28

Chondrocytes

Question 29

Where do you find chondrocytes (sitting in)?

Answer 29

Chondrocyte lacunae

Question 30

What does fibrocartilage consist of?

Answer 30

Dense collagen I fibres added to hyaline matrix

Question 31

What does elastic cartilage consist of?

Answer 31

Elastin fibres added to hyaline matrix

Question 32

Where is type I collagen found?

Answer 32

Skin Bone Tendons Dentin

Question 33

What type of collagen is found in cartilage?

Answer 33

Type II

Question 34

Where is type III collagen found?

Answer 34

Blood vessels Skin

Question 35

Where is type IV collagen found?

Answer 35

Basement membrane

Question 36

What do proteoglycans consist of?

Answer 36

GAGs attached to a core protein

Question 37

What proteoglycan is prominent in cartilage?

Answer 37

Aggrecan

Question 38

What is the function of osteocalcin?

Answer 38

Calcium binding

Question 39

What is the function of osteonectin?

Answer 39

Calcium binding

Question 40

What is the function of osteopontin?

Answer 40

Attachment of cells to matrix

Question 41

What is the function of bone sialoprotein?

Answer 41

Attachment of cells to matrix

Question 42

What proteins allow attachment of cells to bone matrix?

Answer 42

Osteopontin Bone sialoprotein

Question 43

What proteins are involved in calcium binding?

Answer 43

Osteocalcin Osteonectin

Question 44

What are the functions of biglycan and decorin?

Answer 44

Regulation of collagen fibril formation Mineralisation

Question 45

What is woven/coarse-bundle bone classified as?

Answer 45

Immature bone

Question 46

Where is woven bone found?

Answer 46

During development Fracture healing (or pathological bone)

Question 47

What is lamellar bone classified as?

Answer 47

Mature bone

Question 48

What is the difference between lamellar and woven bone?

Answer 48

Lamellar - lower cellular content, regular parallel collagen fibres, heavily calcified

Question 49

What causes lamellae in bone?

Answer 49

Osteoblasts form/secrete osteoid in waves

Question 50

How thick is a lamella in bone?

Answer 50

~5 microns

Question 51

What is between layers of lamellae?

Answer 51

Interlamellar cement

Question 52

How thick is interlamellar cement?

Answer 52

0.1 microns

Question 53

What are the two types of lamellar bone?

Answer 53

Cortical and trabecular

Question 54

What structures does the arrangement of the lamellae in cortical bone give rise to?

Answer 54

Haversian systems/osteons

Question 55

What are the three types of cortical lamellae?

Answer 55

Circumferential Interstitial Concentric

Question 56

What is an Haversian system/osteon?

Answer 56

Concentric system of lamellae surrounding tubular channels containing blood vessels, nerves, etc

Question 57

What are the nutritive canals found in cortical bone called?

Answer 57

Haversian canals (LS) Volkmann’s canals (connect Haversian canals, TS)

Question 58

Why is the number of lamellae in a single osteon limited?

Answer 58

Oldest osteocytes cannot be too far from blood to get nutrients otherwise it will die (bone isn’t permeable)