Block 2

Question 1

What are two benign bone forming lesions?

Answer 1

Osteoid osteoma and osteoblasoma

Question 2

Osteosarcoma

Answer 2

Malignant mesenchymal tumor, most common sarcoma of bone - mets in lungs, poorly delineated

Question 3

What is the mean age of those diagnosed with osteosarcoma?

Answer 3

Male > Female

15 (peaks again in 50s)

Question 4

Atypical mitoses are indicative of ______________.

Answer 4

Malignancy

Question 5

What is the most common benign tumor of bone?

Answer 5

Osteochondroma

Question 6

Where does osteochondroma occur?

Answer 6

Metaphysis of long bones

Question 7

What causes multiple chondromatosis?

Answer 7

Point mutations in IDH1 or IDH12

Question 8

What are the 4 main functions of bone?

Answer 8

1. Infrastructure
2. House bone marrow
3. Specialized CT
4. Reservoir of Ca and phosphate

Question 9

What is the term for the inorganic material of bone matrix?

Answer 9

Hydroxyapatite - Ca, phosphate

Question 10

What is the term for the organic material of bone matrix?

Answer 10

Osteoid (Type 1 Collagen)

Question 11

What is cartilage made up of?

Answer 11

Water and Type II collagen

No mineral, neuronal, or vascular structures

Question 12

Osteoblasts are specialized __________ and function to ______ bone.

Answer 12

fibroblasts

build

Question 13

Bone formation is completed by __________-mediated deposition of Ca within the osteoid.

Answer 13

Osteocalcin

Question 14

Osteocytes function to ________ bone, they occupy ___________, and they have cytoplamsic process that join those of other osteocytes via ____________.

Answer 14

1. Maintain bone (long lived, most numerous cells in bone)
2. Lacunae
3. Gap junctions

Question 15

Osteoclasts function to ____________ bone matrix and they reside in ____________. They are multinuclear since they develop from __________________.

Answer 15

1. Destroy/remodel bone matrix
2. Howship’s lacunae (hollow matrix areas)
3. Fused macrophages

Question 16

Osteoclasts are inhibited by ___________ and activated by _____.

Answer 16

1. Calcitonin

2. PTH

Question 17

How do osteoclasts break down bone matrix?

Answer 17

They attach to ECM via their ruffled border.

They release cathepsin-K and H+ into the microenvironment created

Question 18

Paget’s Disesase

Answer 18

Lose bone mass - extensively multinucleated osteoclasts

Question 19

Osteoblasts mainly reside in the ___________.

Answer 19

Periosteum

Question 20

Osteoclasts reside attached to the bony matrix on the ______________.

Answer 20

Endosteal side

Question 21

What microscopic differences are observed between compact/cortical bone and spongy/trabecular bone?

Answer 21

None.

Question 22

Osteon

Answer 22

cylinder w/ concentric lamellae

Question 23

Lamellae have _______ that contain osteocyte that communicate via ______________.

Answer 23

Lacunae

Canaliculi

Question 24

Haversian canal

Answer 24

BV, nerves, and lymph run through

Question 25

Intramembranous bone development

Answer 25

Osteoblasts deposit osteoid onto mesoderm

Question 26

Endochondral ossification

Answer 26

Osteoblasts deposit osteoid onto cartilage base.

Question 27

What processes use endochondral ossification?

Answer 27

Long bones in embryo and repair after fracture

Question 28

At the diaphysis and epiphyses osteoblasts invade _______________ and secrete osteoid.

Answer 28

calcified cartilage

Question 29

How do bones get long?

Answer 29

1. Somatomedin induces cells to proliferate 2. Get large and hollow out cartilage (zone of hypertrophy) 3. Zone of calcification - becomes basophilic (blue) 4. Zone of ossification - eosinophilic (red)

Question 30

What happens in the zone of calcification?

Answer 30

Collagen X replaces collagen II --> Osteoblasts can secrete osteoid

Question 31

What happens in the zone of ossification?

Answer 31

Deposition of collagen I

Question 32

Bone Repair

Answer 32

1. Macrophages remove debris 2. Chondroblasts secrete hyaline cartilage 3. Osteoblasts replace with bony callus 4. Primary (woven) bone is deposited then replaced by lamellar bone

Question 33

What are three methods of bone tissue engineering?

Answer 33

1. Bone morphogenic proteins (BMP-2 and BMP-7) 2. Adult stem cells (MSC) - Osteoblasts 3. GFs or cells or both are implanted w/i biodegradable sponges made of collagen 1

Question 34

Osteopetrosis

Answer 34

Dense, heavy bone - osteoclasts lack ruffled border

Question 35

Osteoporosis

Answer 35

Fragile - hollow bone - osteoclasts outpace osteogenesis - deviation from bone mineral density mean with age

Question 36

Osteoclast production: Stromal cells in BM are induced by PTH to secrete which 3 things?

Answer 36

1. M-CSF - macrophage proliferation 2. RANK-L - macrophage diff into osteoclasts 3. OPG - osteoprotegerin antagonizes RANK-L??

Question 37

What allows osteoclasts to attach to bone?

Answer 37

Alpha5-beta3 integrin

Question 38

Osteoblasts are inhibited by ______ and induced by ____.

Answer 38

Leptin | BMP

Question 39

Osteoclasts are inhibited by ________ and ___________ and induced by _________.

Answer 39

1. Calcitonin and osteoprotegerin | 2. RANK-L

Question 40

Spikes of PTH favor __________ formation while constant PTH favors ____________ formation.

Answer 40

Osteoblast | Osteoclast

Question 41

What are three types of anti-resorptive drugs?

Answer 41

1. SERMs 2. Bisphosphonates 3. Calcitonin

Question 42

What are other types of bone saving drugs?

Answer 42

1. Osteoprotegerin, inhibit alpha5-beta3, anabolic agents, CBFA-1 master gene

Question 43

Pathogenesis for most soft tissue tumors is ________.

Answer 43

Unknown

Question 44

40% of sarcomas occur in the ______.

Answer 44

Thigh

Question 45

15% of sarcomas arise in _______ -- incidence _________ with age.

Answer 45

Children | Increases

Question 46

What is the most common soft tissue tumor of adulthood?

Answer 46

Lipoma

Question 47

What is the most common soft sarcoma of childhood and adolescence?

Answer 47

Rhabdomyosarcoma