Osteochondrogenesis/Joint Components

Question 1

What are the two types of bone histogenesis?

Answer 1

Intromembranous and endochondral bone formation

Question 2

What is bone remodeling?

Answer 2

The combination of bone formation and resorption

Question 3

Is remodeling faster in primary or secondary bone?

Answer 3

Primary Bone

Question 4

What is the relationship of Ca and bone?

Answer 4

Bone stores Ca used to buffer the levels of Calcium present in the blood.

Question 5

Describe the mineral and H2O content of old osteons.

Answer 5

Highest mineral concentration and lowest H2O content

Question 6

Describe the process of osteoclast activity.

Answer 6

Erosion tunnel and 2 weeks later, apoptosis

Question 7

Describe the process of new bone being laid down

Answer 7

Osteoblasts –> cementing substance (forms cementing/reversal line) –> blasts get caught, become cytes.

Question 8

Name flat bones.

Answer 8

Skull, facial bones, mandible, clavicle, pelvis

Question 9

What type of tissue houses intramembranous bone formation?

Answer 9

Highly vascular mesenchymal tissue

Question 10

List a few signalling factors involved in intramembranous bone formation.

Answer 10

Wnt, hedgehog, FGF, TGF-beta

Question 11

What forms a primary ossification center?

Answer 11

Condensed mesenchymal cells, which differentiate into osteoblasts

Question 12

What do the osteoblasts in intramembranous bone formation secrete?

Answer 12

Osteoid collagen

Question 13

Whats another term for the bone formed with osteoid collagen?

Answer 13

Woven Bone

Question 14

Collagen secretion eventually causes osteoblasts to…

Answer 14

become caught in the matrix, becoming osteocytes. These unite to form trabeculae.

Question 15

How is spongy bone made?

Answer 15

Fusion of bony trabeculae, followed by invasion of blood vessels, and mesenchymal differentiation into bone marrow.

Question 16

What does mesenchymal tissue that doesn’t undergo ossification become?

Answer 16

Periosteum and Endosteum

Question 17

Woven bone is eventually converted into _______ ____ in the outer layers.

Answer 17

Lamellar Bone

Question 18

Endochondral bone formation is used to make ____ _____ using _______ _________ as a scaffold.

Answer 18

Long Bones. Hyaline Cartilage.

Question 19

What are the two stages of endochondral bone development?

Answer 19

Development of primary ossification center, development of secondary ossification centers.

Question 20

Where does the primary center of ossification occur?

Answer 20

The midriff of the diaphysis

Question 21

What does vascularization do to the perichondrium?

Answer 21

Converts chondrogenic cells to osteoprogenitor cells (which form osteoblasts)

Question 22

After osteoprogenitor cell development, perichondrium converts to….

Answer 22

Periosteum

Question 23

First region of bone generated by osteoprogenitors is…

Answer 23

Subperiosteal bone collar

Question 24

How do chondrocytes respond to the development of the subperiosteal bone collar?

Answer 24

Become hypertrophic, secrete collagen X, and VEGF

Question 25

How does the cartilage matrix respond to the development of the subperiosteal bone collar?

Answer 25

Calcification, Inhibited nutrient diffusion, and eventual death of hypertrophies chondrocytes. Lacunae merge forming marrow cavity.

Question 26

Osteoclasts act on the bone collar to allow....

Answer 26

Periosteal buds (vessels, osteoprogenitors, mesenchymal cells) to enter the cavity. Cartilage in the cavity is now calcified.

Question 27

What is the calcified cartilage-calcified bone complex?

Answer 27

Bone matrix (osteoid) calcified on the surface of calcified cartilage.

Question 28

How does calcified cartilage stain?

Answer 28

Basophilic

Question 29

How does calcified bone stain?

Answer 29

Acidophillic

Question 30

How is the primitive marrow cavity enlarged?

Answer 30

Osteoclasts resorb calcified cartilage-calcified bone complex, allowing for eventual bone formation spreading to epiphysis.

Question 31

Where/When do secondary centers of ossification develop?

Answer 31

Epiphyses when diaphyseal ossification is well established

Question 32

How do secondary ossification centers develop?

Answer 32

Basically the same as primary ossification centers...Osteoprogenitors invade, make matrix, replace certilage

Question 33

When initial bone formation is complete, what two sites can cartilage be found? How does this change at approx. age 20?

Answer 33

Initially cartilage at articular surfaces and epiphyseal plates. After bone growth is done, just on articular surfaces.

Question 34

Describe the action occurring in an epiphyseal plate.

Answer 34

Addition of new cartilage. Replacement with bone at epiphyseal end.

Question 35

Describe the cells of the Zone of Reserve

Answer 35

Small, randomly arranged, inactive chondrocytes

Question 36

Describe the cells of the Zone of Proliferation

Answer 36

Rapid mitotic divisions, rows of isogenous cells

Question 37

Describe the cells of the Zone of Cell Hypertrophy and Maturation.

Answer 37

Enlarged Chondrocytes

Question 38

Describe the cells of the Zone of Calcification.

Answer 38

Cartilage Matricies Calcifies, Dead Chondrocytes

Question 39

Describe the cells of the Zone of Ossification

Answer 39

Bone made on calcified cartilage, followed by resorption of the bone/cartilage complex.

Question 40

List the zones of the epiphyseal plate.

Answer 40

Reserve, Proliferation, Cell Hypertrophy & Maturation, Calcification, Ossification

Question 41

Epiphysis enlarges by _________ growth and _______ replacement.

Answer 41

Cartilage. Bone.

Question 42

Hypertrophic chondrocytes secrete what two substances.

Answer 42

Type X Collagen and VEGF

Question 43

Describe the process of post-fracture bone repair.

Answer 43

Blood Clotting --> Osteoprogenitor Proliferation --> Callus Formation --> Fibrous Connective Tissue/Cartilage --> Woven Bone/Bony Callus --> Secondary Bone Formation

Question 44

Hairline fractures heal via what type of bone formation?

Answer 44

Intramembranous

Question 45

What are synarthroses? Example?

Answer 45

Immoveable joints. First rib to sternum, skull bone connections

Question 46

What are amphiarthroses? Example?

Answer 46

Slightly Moveable Joints. IV Discs

Question 47

What are diarthroses?

Answer 47

Synovial Joints (Maximum Movement).

Question 48

What cell type make the external (fibrous) capsular layer of diarthroses?

Answer 48

Dense Connective Tissue

Question 49

What cell type forms the lining of the internal (synovial) capsular layer of diarthroses?

Answer 49

Squamous to cuboidal cells on internal surface

Question 50

What are type A cells of the synovial membrane?

Answer 50

A -- Phagocytic (with well developed Golgi and many lysosomes)

Question 51

What are type B cells of the synovial membrane?

Answer 51

B -- Probably synovial fluid secretors, well developed rER

Question 52

What is osteopetrosis?

Answer 52

Abnormal osteoclast function, leading to mostly woven, not lamellar bone. No marrow cavity development.

Question 53

What is Albers-Schonberg disease?

Answer 53

Deficiency in carbonic anhydrase II makes it so not enough H+ can accumulate to activate lysosomal anzymes.

Question 54

What is osteoporosis?

Answer 54

Loss of bone mass. May be caused by increase in speed of breakdown or slowdown of formation of bone.

Question 55

Rheumatoid arthritis is the product of what type of reaction?

Answer 55

Inflammatory

Question 56

What type of cells are activated in Rheumatoid Arthritis?

Answer 56

CD4 T Cells

Question 57

CD4 T Cells produce what to stimulate macrophage activity?

Answer 57

IL-15

Question 58

What inflammatory cytokines are involved in rheumatoid arthritis?

Answer 58

TNF-alpha, IL-1, IL-6, metalloproteases