Bone & Cartilage

Question 1

What is the CT that surrounds the outside of compact bone

Answer 1

Periosteum

Question 2

What is the CT that lines inner surface of bone facing marrow cavity and haversian canals

Answer 2

endosteum

Question 3

What are osteoblasts

Answer 3

secrete bone matrix (uncalcified); found only at the boundary bet bone and periosteum/endosteum

Question 4

What are osteocytes

Answer 4

osteoblasts that have become “trapped” within lacunae of calcified matrix; connected to one another by gap jxns via processes that extend through canaliculi for the transport of nutrients and wastes.

Question 5

what are osteoclasts

Answer 5

large, blood derived (related to macrophages) multinucleated cells that degrade the bone matrix (secretes H+ and lysosomal enzymes) for reabsorption.

Question 6

What is bone matrix composed of

Answer 6

Organic: collagen (type 1) GAGs, glycoproteins

Inorganic salts: Calcium phosphate crystals

Question 7

what are details of immature bone

Answer 7

layed down randomly; forms trabeculae that grow together.

Question 8

Osteon=

Answer 8

concentric rings of lamellae. With lacunae

Question 9

Bone is highly vascular:

Answer 9

blood vessels within marrow
blood vessels peripherate in marrow
blood vessels in matrix of bone.

Question 10

What is the haversian canal

Answer 10

the vessels that run through the center of the osteon

Question 11

what is volkmanns canal

Answer 11

interconnect the central canal and is a way to get blood vessels bet central canals

Question 12

what are canaliculi

Answer 12

small canals; connect neighboring lacunae

Question 13

immature bone has a randomly:

Answer 13

interwoven collagen fiber HAP matrix

Question 14

Osteoblasts lay down new:

Answer 14

matrix in concentric lamellae

Question 15

Cartilage is avascular CT T/F

Answer 15

T

Question 16

What type of collagen in cartilage

Answer 16

Type II

Question 17

Chondrocytes, unlike osteocytes:

Answer 17

Actively secrete matrix

Question 18

where does chondroblast exist

Answer 18

between cartilage and CT; differentiate into chondrocytes as soon as they completely get surrounded by matrix.

Question 19

What dont you see in cartilage

Answer 19

No vasculature!

Question 20

what is the CT associated with cartilage

Answer 20

perichondrium; dense CT; contains fibroblasts and type I collagen. Has blood vessels but dont go into cartilage matrix.

Question 21

Perichondrium is NOT present in:

Answer 21

articular surfaces and epiphyseal plates

Question 22

what are chondroblasts derived from. They secrete matrix via ___ growth

Answer 22

progenitor cells in perichondrium; appositional

Question 23

Chondrocytes secrete matrix via ____growth

Answer 23

interstitial; actively divide

Question 24

What is hyaluronic acid composed of

Answer 24

a GAG; extremely long that has proteins, smaller GAGs attached via aggregan molecules

Question 25

What is the cartilage matrix composed of

Answer 25

1. Water
2. Fibers: hyaline (type II collagen), elastic (type I and elastic fibers), and fibrocartilage (type I and II collagen)
3. Hyaluronic acid
4. Proteoglycans & GAGs: Aggrecan, choidroitin sulfate and keratin sulfate.

Question 26

The cartilage matrix forms a large molecule with a lot of ____charge which binds cations and water forming hydrated gel that is resistant to compression

Answer 26

negative

Question 27

What are features of hyaline cartilage

Answer 27

1. homogenous, amourphous matrix
2. “typical” cartilage
3. Not uniformly distributed: capsular, territorial and interterritorial matrix

Question 28

where is hyaline cartilage found

Answer 28

1. articular surfaces
2. epiphyeal plates
3. costal cartilages
4. thyroid
5. trachea
6. fetal skeleton

Question 29

What are features of elastic cartilage

Answer 29

1. contains elastic fibers

2. found in pinna of ear, ear canal, and epiglottis

Question 30

what are features of fibrocartilage

Answer 30

1. contains fibroblasts and type 1 collagen fibers. (inc tensile strength)
2. resist compression bc it has hyaluronic acid in its ground substance
3. NO perichondrium
4. Found at symphysis of joints (pubic) and intervertebral discs), and articular discs and menisci.

Question 31

Type I cartilage is very ___

Answer 31

eosinophilic; so fibrocartilage will appear very pink.

Question 32

fibrocartilage have ___groups of cells

Answer 32

columnar.

Question 33

What is endochondral ossification

Answer 33

bone is formed through the ossification of a cartilagenous model.

Question 34

what is intermembranous ossification

Answer 34

mesenchyme within CT differentiated directly to osteoblasts which create bone de novo.

Question 35

what are the zones of endochondral ossification

Answer 35

1. zone of resting cartilage: quiscent cartilage @ end of epiphyseal plate
2. zone of proliferation: chondrocytes actively divide producing columns of isogenous cells.
3. zone of hypertrophy: chondrocytes inc in size and accumulate glycogen
4. zone of calcification: chondrocytes degenerate; HAP crystals form within cartilage.
5. zone of ossification: Osteoblasts synthesize bone over the layer of calcified cartilage.

Question 36

What are phases of fracture repair

Answer 36

1. Hematoma (blood clot)
2. CT invades hematoma
3. Build precallus (big knot of cartilage in between two pieces of broken bone)
4. Calcification and further ossification creates immature bone = callus
5. Remodeling creates mature bone

Question 37

Scurvy is related to:

Answer 37

Wound healing: all collagen sythesis requiers Vitamin C for an intial step to hydroxylate proline molecules. Another problem could be bone deformation, and weak bones.