Lecture 11

Question 1

T/F: calcification can occur anywhere in the body.

Answer 1

True

Question 2

What structure of the body is intramembranous bone formation associated?

Answer 2

Calvaria

Question 3

In intramembranous bone formation what does the primary ossification center become?

Answer 3

Trabecula

Question 4

What type of growth primarily occurs in intramembranous bone formation?

Answer 4

Appositional growth

Question 5

In endochondral bone formation cartilage is ________ by bone.

Answer 5

Replaced

Question 6

Steps of endochondral bone formation (summarized)

Answer 6

-1^ ossification center = future diaphysis of cartilage model -Chondrocytes become hypertrophic and secreate vascular endothelial growth factor (VEGF) -BV break thru perichondrium, bringing in osteoprogenitor cells (bone forming cells) -Hypertrophic cartilage undergoes apoptosis, leaving calcified matrix -Osteoblasts use calcified strands as substrates for deposition of osteoid -osteoid is calcified

Question 7

DEB (developing endochondral bone) experiences _______ growth.

Answer 7

interstitial

Question 8

PB (periosteal bone) experiences _______ growth.

Answer 8

Appositional

Question 9

What do osteoblasts do?

Answer 9

-Secrete bone matrix -more darkly stained & irregularly shaped - have alkaline phosphatase and Vit D3 - osteocalcin prtn (high affinity for hydryoxapatite= helps bind to organic component of bone) - RANKL

Question 10

What are osteocytes?

Answer 10

Maintain bone matrix -help cntrl Ca+2, and phosphate levels -derived from osteoblasts

Question 11

What are osteoclasts?

Answer 11

remodel bone thru resorption - dissolve both inorganic and organic matrix - very large and multinucleated

Question 12

Where do osteoprogenitor cells derive from and what do they do?

Answer 12

-Mesenchyme of embryonic somites *** they are stem cells that give rise to osteoblasts and bone lining cells (adult stem cells)

Question 13

Where do osteoclasts derive from and what are they involved in?

Answer 13

• from monocyte lineage - ARF cycle = occurs at remodeling sites & during development

Question 14

What happens with high PTH levels? Low PTH levels?

Answer 14

• osteoblasts stim. release of osteoclasts == bone resorption - increase bone formation by osteoblasts

Question 15

_____ dissolves organic matrix. _____ dissolves inorganic matrix.

Answer 15

• Cathepsin K - HCl

Question 16

Label the epiphyseal plate

Answer 16

A: Proliferative zone

B: Hypertrophic zone

C: Calcification zone

Question 17

Define joint

Answer 17

Where 2 bones come together

Question 18

Cartilagionous joints are known as _______.

What are the 2 types?

Answer 18

• amphiarthroses
• Symphysis (fibrocartilage; ex = intervertebral discs)
• Sychondrosis (hyaline cartilage; ex = EP)

Question 19

Fibrous joints are known as ________.

What are the 3 types?

Answer 19

Synarthroses

• Suture (calvaria)
• Gomphosis (peg in socket - teeth in alveoli)
• Syndesmosis (interosseous firbrous membrane)

Question 20

Synovial joints are known as ________.

What are the types?

Answer 20

Diarthroses

• Monoaxial = Hinge and Pivot
• Biaxial = Condyloid and Saddle
• Triaxial = Ball-and-socket

Question 21

What type of joint is this?

Which portion is innervated?

Which portion is vascularized?

Answer 21

• Synovial joint
• Outer fibrous capsule
• Inner synovial membrane

Question 22

Histology of Synovial joint

Articular cartilage is composed of what? and lacks what?

It is not lined by _______

Answer 22

• Hyaline cartilage
• Perichondrium
• synovial membrane

Question 23

Histology of Synovial joint

Joint capusle made of what? Lined by _____

Answer 23

• Vascularized dense CT
• Synovial membrane

its attached to edges of articular cartilage

Question 24

Histology of Synovial joint

Synovial membrane is highly _______

Has NO _______

Answer 24

• highly vascularized
• no basal lamina

(1-3 layers of synovial cells)