Lecture 7

Question 1

Bone?

Answer 1

Specialized CT

Question 2

Is Bone Vascular?

Answer 2

Yes, blood supply allows for bone repair

Question 3

Bone can be ___ or ___?

Answer 3

-Compact (made of osteons)
-Spongy (trabecular + NO osteons)

Question 4

Bone is covered by?

Answer 4

Periosteum (dense irregular CT)

Question 5

Function of Bone?

Answer 5

Structural support, anchoring muscle, calcium storage

Question 6

Cells + ECM (fibers)=?

Answer 6

Intercellular component of Bone

Question 7

Osteocytes are housed in?

Answer 7

Lacunae in the matrix

Question 8

~90% of calcium is stored in the?

Answer 8

Bone as matrix

Question 9

Matrix Components?

Answer 9

-Calcium phosphate (hydroxyapatite crystals)
-Type I collagen –> produced by osteoblasts
-Ground substance = PGs + GAGs (keratin/chondroitin sulfate) + Glycoproteins (laminin, fibronectin)

Question 10

Fibroblasts produce?

Answer 10

Collagen Fibers

Question 11

Fibroblasts, Chondroblasts, and Osteoblasts produce?

Answer 11

Collagen Fibers

Question 12

Fibrocartilage also has?

Answer 12

Type I collagen fibers

Question 13

Epiphysis?

Answer 13

Ends of Long bones (made up of spongy bone) (contains red marrow –> produces RBCs)

Question 14

Epiphyseal Line?

Answer 14

Growth Plate (made up of hyaline cartilage –> replaced with compact bone)

Question 15

Diaphysis?

Answer 15

Shaft of Long Bones (made up of compact bone) (contains medullary cavity)

Question 16

Medullary Cavity?

Answer 16

Site of Bone Marrow

Question 17

Periosteum?

Answer 17

Outer covering of dense irregular CT covering bone (contains osteoblasts)

Question 18

Bone Marrow can be?

Answer 18

Red or Yellow
(red= blood cells)
(yellow= adipose (fat) cells)

Question 19

Compact Bone is made up of?

Answer 19

Lamellae

Question 20

Lamellae?

Answer 20

Rings of Thin Bone

Question 21

Perichondrium covers?

Answer 21

Cartilage and contains chondroblasts

Question 22

Compact Bone has Osteons, Spongy Bone has?

Answer 22

Trabeculae

Question 23

Bone Marrow?

Answer 23

Innermost layer of bone (located in medullary cavity as blood or adipose cells)

Question 24

Endosteum?

Answer 24

Inner CT lining medullary cavity (contains osteoblasts)

Question 25

Haversian Systems?

Answer 25

Lamellae around a central canal (Compact Bone)

Question 26

Haversian Systems?

Answer 26

Lamellae around a central canal (Compact Bone)

Question 27

Basic unit of compact bone?

Answer 27

Osteons

Question 28

Osteons are made up of?

Answer 28

Lamellae (rings of thin bone) around a central (haversian) canal (mature bone cells (osteocytes) sit in lacunae of bone matrix)

Question 29

Canaliculi?

Answer 29

Small tunnels in bone matrix (connect neighboring cells in lacunae for cell-cell communication via gap junctions)

Question 30

Bones under constant stress?

Answer 30

Remodel fastest

Question 31

Osteoblasts?

Answer 31

Immature bone cells (secrete matrix --> type I collagen fibers) (mitotically active --> further divide to form osteocytes)

Question 32

Osteocytes?

Answer 32

Mature bone cells (housed in lacunae) (maintain bone matrix) (help absorb calcium into blood with PTH)

Question 33

Osteoclasts?

Answer 33

Bone Remodeling Cells (housed in Howship's lacunae with enzymes to digest bone) (PTH activates osteoclasts --> increases blood calcium) (Calcitonin inhibits osteoclasts --> decreases blood calcium)

Question 34

PTH activates?

Answer 34

Osteoclasts which increase blood calcium

Question 35

Calcitonin inhibits?

Answer 35

Osteoclasts which decrease blood calcium

Question 36

Bone Remodeling?

Answer 36

-Osteoclasts digest bony matrix of an area (resorption bay) -Osteoblasts follow behind osteoclasts + deposit new bony matrix

Question 36

Bone Remodeling?

Answer 36

-Osteoclasts digest bony matrix of an area (resorption bay) -Osteoblasts follow behind osteoclasts + deposit new bony matrix

Question 37

Osteoid?

Answer 37

Uncalcified bone matrix

Question 38

Intramembranous Bone Formation?

Answer 38

-Occurs in mesenchyme (embryonic CT) --> mesenchyme cells turn into osteoblasts -Osteoblasts secrete boney matrix (osteoid) which create bony spicules -As boney spicules enlarge, they become interconnected forming trabeculae

Question 39

Intramembranous Bone Formation expands by?

Answer 39

Appositional Growth (ex. osteoblast mediated bone growth) (bone is added to surface; this is the only way bone grows)

Question 40

Endochondral Bone Formation?

Answer 40

-Occurs in hyaline cartilage --> mesenchymal cells turn into osteoblasts at bony collar near diaphysis -Chondrocytes within cartilage hypertrophy --> secrete alkaline phosphate --> then calcify -Osteoblasts cover calcified cartilage with its own uncalcified bony matrix (osteoid)

Question 41

Bony Collar is formed by?

Answer 41

Intramembranous bone formation via osteoblasts

Question 42

Bony Collar cuts off?

Answer 42

Supply to the cartilage, thus chondrocytes die

Question 43

Bony Collar cuts off?

Answer 43

Supply to the cartilage, thus chondrocytes die

Question 44

Calcified cartilage stains?

Answer 44

Purple

Question 45

Osteoid stains?

Answer 45

Pink

Question 46

Zone of Ossification?

Answer 46

Pink Hue/Tone indicated Type I collagen because collagen stains pink

Question 47

Zone of Calcification?

Answer 47

Cartilage is now calcified

Question 48

Zone of Hypertropy?

Answer 48

Where chondrocytes grow in size (get puffy) (start to calcify cartilage)

Question 49

Zone of Proliferation?

Answer 49

Has Isogenous Groups

Question 50

Zone of Reserve?

Answer 50

Has no Isogenous Groups just a bunch of lacunae

Question 51

(Top to Bottom) Zones of Bone?

Answer 51

-Zone of Ossification -Zone of Calcification -Zone of Hypertrophy -Zone of Proliferation -Zone of Reserve

Question 52

Bone Fracture Healing?

Answer 52

1) Hematoma formation 2) Fibrocartilage Callus Formation 3) Bony Callus Formation 4) Bone Remodeling