Bone

Front 1

Lamellar Bone

Back 1

Bone made from alternating alignments of collagen fibers (in adjacent lamella)

Front 2

Differences between bone and cartilage

Back 2

Bone is vascularized and innervated

Bone ECM has a complex architecture and is constantly being remodeled

Cartilage can undergo appositional and interstitial growth, while bone can only undergo appositional growth.

Front 3

Functions of bone

Back 3

structural support and protection of internal organs
locomotion
mineral storage
Acts in hematopoiesis and calcium homeostasis

Front 4

Cortical/compact bone

Back 4

Calcified bone

Front 5

Periosteum

Back 5

Analagous to perichondrium. Has inner osteogenic cellular layer that generates and repairs bone and an outer fibrous layer that merges with surrounding connective tissue. Has lymphatic drainage (bone tissue doesn't)

Front 6

Sharpey's fibers

Back 6

The attachment of tendons and ligaments to bone via insertion of their collagen fibers with the periosteal and bone collagen fibers

Front 7

Trebecular/cancellous/spongy/medullary bone

Back 7

Thin plates of bone with large marrow spaces between them

Front 8

Endosteum

Back 8

Covers trabecular that project inwardly from compact bone and into the marrow(contains osteoprogenitor cells, inactive osteoblasts, and reticular fibers)

Front 9

Red marrow

Back 9

Hematopoietic tissue in which blood cells are formed. In adult, most common in axial skeleton

Front 10

Yellow marrow

Back 10

Replaces red marrow in appendicular skeleton of the adult. Increase of adipose tissue.

Front 11

Components of Osteoid

Back 11

Organic material of bone
Type 1 collagen
GAG's: chondroitin, keratan sulfates, hyaluronin
Adhesion glycoproteins (osteonectin, sialoprotins, alkaline phosphatases)
Growth factors, cytokines, interleukins, bone morphogenetic protein, and RANKL's and CSF-M that lead to osteoclast activation

Front 12

Osteoid

Back 12

Organic part of bone that supports production of inorganic material of bone. It is produced by the osteoblast

Front 13

Hydroxyapatitie

Back 13

Ca10(PO4)6(OH)2 crystals

Front 14

Canaliculi

Back 14

processes from the osteocytes that contact other osteocytes, forming gap junctions. Provides a way to contact capillaries

Front 15

Osteoprogenitor

Back 15

Mesenchymal stem cell present in the endosteum or periosteum. Can differentiate into either osteoblasts (in highly vascularized areas), fibroblasts, or chondroblasts (in avascular regions)

Front 16

Haversian system

Back 16

central Haversian canal containing the vascular supply of the bone- surrounded by 4-20 concentric lamellae of collagen fibers (these contain osteocytes)

each surrounded by a cement line

Constantly being remodelled

Front 17

Volkmann's canals

Back 17

No concentric lamella. These contain blood vessels connecting adjacent Haversian canals

Front 18

Interstitial lamellae

Back 18

Remains of concentric lamellae comprising osteons partially removed during remodeling

Front 19

Circumferential lamellae

Back 19

Oriented parallel to outer surface of the bone

Front 20

Howship's lacnuae

Back 20

depressions in bones made by osteoclasts

Front 21

Osteoclasts

Back 21

Arise from macrophage cells. Large, very eosinophilic, and multinucleated.

Can resorb bone, forming resorption tunnels in compact bone or Howship's lacunae in trebecular surfaces. They become attached to the bony surface by a clear sealing zone of actin filaments and ECM adhesion molecues and exocytose lysosomal hydrolytic enzymes, MMPs, and cathepsin-K proteases, as well as carbonic anhydrase derived protons.

Marker for active ones is tartrate-resistant acid phosphatase (TRAP)

Front 22

Osteoblasts

Back 22

Basophilic and cuboidal. Line trebecular surfaces and produce new bone via intramembranous ossification

Front 23

Bone remodelling

Back 23

Occurs appositionally.
Osteoclasts clear away bone, osteoblasts come back in and rebuild.

Front 24

Ruffled border

Back 24

Where osteoclastic exocytosis of lysosomal hydrolytic enzymes occurs

Front 25

Osteon

Back 25

Haversian system

Front 26

Intramembranous Bone Formation

Back 26

Bone differentiated directly from mesenchyme. Osteoblasts lay down osteoid, which becomes calcified, woven bone. Occurs in frontal and parietal bones, parts of the mandible, maxilla, occipital, and temporal bones.

Front 27

Endochondral Bone Formation

Back 27

Bone formed from hyaline cartilage primordium.
1. Formation of primary ossificaiton center.
2. Formation of secondary ossification center
3. Epiphysis - growth plate and its zones

Front 28

Osteogenesis

Back 28

Osteoblasts secrete matrix vesicles containing osteoid, calcium, and phosphorus. Alkaline phosphatase hydrolyzes pyrophosphate, which is hydrolyzed to phosphate ions that can form hydroxyapatite

Front 29

Formation of primary ossificaiton center

Back 29

Osteoprogenitor cells differentiate into osteoblasts, producing a bony collar at the diaphysis (and a name change to periosteum). Chondrocytes secrete type X collagen and VEGF.

Front 30

Formation of secondary ossification center

Back 30

Vascular buds break into epiphyses. Matrix calcifies as it does in primary ossification

Front 31

Epiphyseal disk or plate

Back 31

Cartilage that is left over from the original primordium. Remains throughout childhood and puberty.

Front 32

Zone of reserve cartilage

Back 32

Part of the hyaline cartilage in growing bone. Little mitosis or synthesis of new cartilage. Mitosis stimulated by PTH-rP

Front 33

Zone of cartilage cell multiplication (proliferative zone)

Back 33

Part of the hyaline cartilage in growing bone. High mitotic activity and synthesis of new matrix with cells in isogenic cell nests. PTH-rP induces chondrocyte mitosis and delays differentiation into hypertrophic state

Front 34

Zone of cartilage cell hypertrophy

Back 34

MMPs degrade matrix, VEFG and type X collagen are secreted. Chondroblasts hypertrophy.

Front 35

Zone of cartilage mineralization

Back 35

Cartilage matrix is calcified as chondrocytes die via apoptosis (calcification limits diffusion). Blood vessels invade resorption channels.

Front 36

Zone of ossification

Back 36

Osteoblasts align spicules of cartilage and lay down osteoid

Front 37

Puberty

Back 37

Ossification accelerates and overtakes the rate of cartilage expansion. Estrogen inactivates the growth plate.

Front 38

PTH

Back 38

Hypocalcemia - more PTH secretion - stimulates osteoblasts to release cytokines IL-G and RANK ligand, and M-CSF

Front 39

IL-6 and RANK ligand

Back 39

induce existing pre-osteoclasts to fuse and resorb bone matrix, releasing serum calcium and suppressing osteoblast secretion of matrix

Front 40

M-CSF

Back 40

induces increased proliferation of osteoclast mononuclear precursors

Front 41

Vitamin D hydroxylation

Back 41

Occurs in liver and kidney, increasing intestinal and renal absorption

Front 42

Calcitonin

Back 42

Minimal role in humans. Secreted by thyroid. Opposes effect of PTH. Decreases osteoclast activity and increases osteoblast activity

Front 43

GH and IGF-1

Back 43

GH stimulates IGF-1 to stimulate chondrocytes in growth plate

Front 44

Estradiol and testosterone

Back 44

increase bone mass by limiting osteoblast cytokine production and shifting balance to osteoblast matrix deposition

Front 45

Synovial cavity

Back 45

between articular cartilage of two bones in freely moving joinrs

Front 46

Joint capsule

Back 46

Encloses synovial cavity. Made from extensions of the periostea around the joint

Front 47

Synovial fluid

Back 47

reduces friction between hyaline cartilage of opposing articular surfaces

Front 48

Synovial membrane

Back 48

lines synovial cavity. Made of two non-epithelial cells without a basal lamina - macrophage-like (type A) and fibroblast-like (type B)

Front 49

Menisci

Back 49

C-shaped fibrocartilagenous extensions into the synovial cavity of the knee; inner edge is avascular fibrocartilage and the outer edge is dense fibrous connective tissue with blood vessels and nerves

Front 50

Suture

Back 50

a fibrous joint; thin ligamentous sheet connecting bones in the skull

Front 51

Syndesmoses

Back 51

Fibrous joint - ligaments connecting bone

Front 52

Gomphoses

Back 52

Fibrous joint - ligament attaching tooth root to bone

Front 53

Amphiarthroses

Back 53

Cartilagenous joint - intervertebral disk joint

Front 54

Nucleus pulposus

Back 54

Inner mucoid core of the flexible disc in the intervertebral disc. It absorbs shock.

Front 55

Anulus fibrosus

Back 55

outer fibrocartilagnous casing of the nucleus pulposus that distributes shock across the joint

Rupture is a herniated disk

Front 56

Synchondroses

Back 56

Hyaline cartilage in growth plate that directly connects head and shaft regions of bone - limited to no movement.