Msi Week 1: Histology Lecture 2

Front 1

List the general contents of bone organs (7).

Back 1

1. Bone tissue
2. Other connective tissue
3. Fat
4. Cartilage
5. Bone marrow
6. Blood vessels
7. Nerves

Front 2

List the elements that compose bone tissue.

Back 2

1. Cells (osteoblasts, osteocytes..)
2. Extracellular matrix (type I collagen, ground substance)
3. Hydroxyapatite crystals (within collagen fibrils and ground substance)

Front 3

Describe the gross appearance of the inside and outside layers of bone.

Back 3

Inside --> Spongy (trabecular, cancellous)
Outside --> Compact (dense, cortical)

Front 4

Cylindrical units within mature bone are called..?

Back 4

Osteons

Front 5

Which type of bone (immature or mature) has randomly oriented cells with interlacing arrangements of fibers?

Back 5

Immature bone (primary, woven)

(mature bone forms cylindrical units and is structurally superior)

Front 6

Is lamellar bone immature or mature bone?

Back 6

Mature

Front 7

Is woven bone immature or mature bone?

Back 7

Immature

(gets replaced by lamellar/mature bone)

Front 8

Is compact bone in the adult composed of lamellar or woven bone?

Back 8

Lamellar

Front 9

Name the canals that blood travels through as it moves from the marrow cavity through the bone to the periosteum.

Back 9

Haversian canal --> --->Volkmann's canal

Front 10

Name the canal located in the center of an osteon.

Back 10

Haversian canal

Front 11

Name of remnants of previous concentric lamellae.

Back 11

Interstitial lamella

Front 12

List the components of an osteon.

Back 12

1. Haversian canal (contains blood vessels)
2. Concentric lamellae
3. Lacunae (contain osteocytes)
4. Canaliculi

Front 13

What canals connect blood vessels of adjacent Haversian canals?

Back 13

Volkmann's canals

Front 14

Name the 5 cells of bone tissue.

Back 14

1. Osteoblasts (bone forming cells)
2. Osteocytes (in lacunae)
3. Osteoprogenitor cells (stem cells of periosteum)
4. Bone lining cells (quiescent osteoblasts of endosteum)
5. Osteoclasts (bone resorbing cells)

Front 15

Name of bone-forming cells.

Back 15

Osteoblasts

Front 16

Name of stem cells of periosteum.

Back 16

Osteoprogenitor cells

Front 17

Name of quiescent osteoblasts of endosteum.

Back 17

Bone lining cells

Front 18

Bone resorbing cells.

Back 18

Osteoclasts

Front 19

Which cells can be either quiescent osteoblasts or osteoprogenitor cells?

Back 19

Endosteal cells

Front 20

Beginning with mesenchymal stem cells, describe the differentiation process to osteocytes.

Back 20

1. Mesenchymal stem cell -->
2. Osteoprogenitor cells --->
3. Osteoblasts --->
4. Either: osteocytes or bone-lining cells

Front 21

What do osteoblasts synthesize?

Back 21

Osteoid
(unmineralized bone matrix)

Front 22

What structures allow cellular processes in canaliculi to be in contact with each other?

Back 22

Gap junctions

Front 23

Osteocytes are entrapped within ________.

Back 23

Lacunae

Front 24

Which cellular layer are osteoprogenitor cells located within?

Back 24

Periosteum
(also in endosteum in early development-- but not in adult bones).

Front 25

Simple squamous cells on all bone surfaces.

Back 25

Bone lining cells (quiescent osteoblasts)

Front 26

Bone lining cells are located within which layers of bone?

Back 26

Periosteum and endosteum

Front 27

Osteoclasts are derived from...

Back 27

Fusion of monocytes

Front 28

Osteoclasts form a subosteoclastic compartment known as...

Back 28

Howship's lacunae

Front 29

How do osteoclasts break down bone tissue?

Back 29

They create an acidic environment via proton pumps and release hydrolytic enzymes onto the bone surface.

Acidic environment does 2 things:
1. Demineralizes osteoid (Ca2+ deposits leak out)
2. Provides optimal enviro for acid hydrolases

Front 30

Name the 2 types of ossification.

Back 30

1. Intramembranous ossification
2. Endochondral ossification

Front 31

Type of ossification in which bone is formed directly by condensation of mesenchymal cells.

What type of bones are formed this way?

Back 31

Intramembranous ossification

*Flat bones of skull and face, mandible, and clavicle.

Front 32

Type of ossification in which bone is formed in relation to a previously formed cartilage (hyaline) model.

What types of bones are formed this way?

Back 32

Endochondral

*Bones of extremities, axial skeleton.

Front 33

Name the 6 general steps of endochondral ossification.

Back 33

1. Formation of cartilage model
2. Formation of periosteal bone collar
3. Hypertrophy of chondrocytes (production of Type II collagen)
4. Invasion of blood vessels (osteoprogenitor and hemopoietic cells)
5. Production of bone matrix on calcified cartilage.

Front 34

Which cells lay down bone matrix on calcified cartilage model during bone development and growth?

Back 34

Osteoblasts

Front 35

What structure forms between the primary and secondary ossification centers?

Back 35

Epiphyseal plate

Front 36

Which region of a long bone permits growth throughout adolescence?

Back 36

Epiphyseal plate

Front 37

Describe the 4 zones of the epiphyseal plate.

Back 37

1. Reserve (resting) zone--> source of new cells
2. Proliferative zone --> produce new cartilage matrix to lengthen bone
3. Hypertrophy and calcification zone ---> apoptosis occurs here to maintain width of epiphyseal plate
4. Ossification zone --> vascular invasion

Front 38

In which zone of the epiphyseal plate is the cartilage matrix produced?

Back 38

Proliferation zone

Front 39

During bone growth at the epiphyseal plate, resorbed cartilage is replaced by...?

Back 39

Trabecular (spongy) bone
(*Woven bone first, then lamellar bone later)

Front 40

What type of growth occurs to increase bone width at the periosteum? (interstitial or appositional?)

Back 40

Appositional

Front 41

During bone remodeling, osteoclasts form ________ canals to form new osteons.

Back 41

Resorption canals.