Chapter 6: Bone And Cartilage

Front 1

Cartilage

Back 1

- semirigid connective tissue that is weaker than bone but more flexible and resilient

- cells scattered throughout a matrix of protein fibers with ground matrix

Front 2

Chondroblasts

Back 2

- cells that produce the matrix of the cartilage

Front 3

Chondrocytes

Back 3

- chondroblasts that are produced and secreted

Front 4

Function of Cartilage

Back 4

- support soft tissue

- provides gliding surface where to bones meet

- provides model for the formation of most of the bones

Front 5

Interstital

Back 5

- growth within the cartilage

- growth in length

Front 6

Appositional

Back 6

- growth on the outside of the cartilage

- growth in diameter/thickness

Front 7

Intersitional Growth Steps

Back 7

1) chondrocytes housed in the lacunae undergo mitotic cell divison

2) the two new cells occupy a single lacuna

3) cells begin to synthesize ans secrete new cartilage matrix and they are pushed apart and now reside in their own lacunae

4) new cells in thier own lacunae are chondrocytes

Front 8

Appostitonal Growth

Back 8

1) stem cells at internal edge of perichondrium divide, forming new stem cells and committed cells

2) committed cells differentiate into chondroblasts

3) chondroblasts located at periphery of old cartilage produce and secerte new cartilag matrix. they push apart and become chondorcytes occupying thier own lacunae

4) new matrix on pheripherally is produced

Front 9

Bone

Back 9

- primary component is bone connective tissue

Front 10

Functions of Bone

Back 10

- suport and protection

- movement

- hemopoiesis: the process of blood production

- storage for minerals and energy

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Long Bones

Back 11

- have greater length than width

Front 12

Short Bones

Back 12

- lengnth nearly equal to their width

- external surface covered by compact bones and interior by spongy bone

Front 13

Flat Bones

Back 13

- have flat thin sufaces

- composed of rough parallel surface of compact bone with layer of internally placed spongy bone

Front 14

Irregular Bones

Back 14

- elaborate complex shapes

Front 15

Diaphysis

Back 15

- shaft, or long part of the bone

Front 16

Epiphysis

Back 16

- each end of the bone

- en larged to strengthen the bone

- composed of an outer layer of compact bone and inner spongy bone

Front 17

Metaphysis

Back 17

- regin between the epiphysis and diaphysis

- contains the epiphyseal palte and thin layer of hyaline cartilage

Front 18

Articular Cartilage

Back 18

- thin layer of cartilage covering the epiphysis at joint surfaces

Front 19

Medullary Cavity

Back 19

- hollow space witin the diaphysis

- yellow bone marrow inside

Front 20

Endosteum

Back 20

- incomplete layer of cells that covers all internal surfaces of the bones

Front 21

Periosteum

Back 21

- covers outersurface of bone

- except for areas with articular cartilage

- made of dense irregular connective tissue

Front 22

Osteoprogenitor

Back 22

- stem cells derived from msesenchyme

- when they dvide they produce another stem cell and committed cell that matures to become an osteblasts

- located at periostem and endosteum

Front 23

Osteoblasts

Back 23

- fromed form osteoprogenitor comitted cell

- secrete initial semi solid organic form of bone called osteiod

- then osteiod hardens and becomes as a result of calcuim slat despostion

- osteoblasts produce new bone and secrete and become osteocytes

Front 24

Osteocytes

Back 24

- matured bone cells that derive form osteoblasts

- reside in small spaces in the lacunae

- maintain the bone matrix

- sends infomration to osteoblasts ans may resut in bone matrix

Front 25

Osteoclasts

Back 25

- large multicunealr phagocytic cells

- derive from fused bone marrow

- located within or adjacent to a drepression or pit on bone surface

- bone reabsorption by secreting hyrochloric acid which dissolves the mineral parts of the bone matrix

- lysosomes within the osteoclasts secerte enzymes that dissolve organic part of matrix

Front 26

Osteon

Back 26

- the basic unit of compact bone

- three dimensional structure that has several components

Front 27

Central Canal

Back 27

- cylindrical channel that is n the center of osteon

- inside of canal are blood vessels and nerves

Front 28

Cocentric Lamellae

Back 28

- rings of connective tissue that surrond the centeral cannal and from the bulk of the osteon

- contain collagen fibers oreintated in one direction opposite of the one next to it

Front 29

Osteocytes

Back 29

housed in the lacunae and between adjacent ocentric lamaellae

Front 30

Canaliculi

Back 30

- interconnecting channels within bone connective tissue that extend from each lacaunae, travel to each lamaelle and connect other cunae and central canal

Front 31

Interstitial Lamellae

Back 31

- leftover part of osteon that have been partially reobserved

Front 32

Ossification

Back 32

- formation and development of bone connective tissue

- begins in embryo and continue to grow in childhood and adolescence

Front 33

Step 1 of Ossification

Back 33

- ossification centers form within thick regions of mesenchyme and divide and committed cells become osteoprogenitor cells

- osteoprogenitors turn into osteoblasts that secrete semisolid organic components of bone matrix called osteoid

Front 34

Step 2 of Ossfication

Back 34

- osteoid goes through calficification

- calcium salts are depositied onto the osteiod and then cystalized

- calcification entraps osteoblasts within lacuane in the matrix and become osteocytes

Front 35

Step 3 of Ossification

Back 35

- woven bone and its surronding periosteum forms

- woven bone: newly formed connective tissue that immature and unorganized

- woven bone is replaced by lamellar bone

- mesenchyme that surronds the woven bone begins to thicken that forms periosteum

- oesteoblasts are continually produced as mesenchymal cells grow and develope

Front 36

Step 4 of Ossification

Back 36

Lamellar bone replaces woven bone as compact bone and spongy bone form

Front 37

Step 1 of Endochondrial Ossification

Back 37

- the fetal hyaline cartilage developes

- chondroblasts have become chondrocytes trapped with lucane

- perichondrium surrongs cartilage

Front 38

Step 2 of Endochondrial Ossification

Back 38

- cartilage calcifies and a periosteal bone collar forms

- at center of cartilage model chondrocytes start to hypertrophy and resorb some of the surronding cartilage matrix producing larger holes in the matrix

- chondrocytes die in the region and result in large holes where they once where

- stem cells in the pericardium divide to form osteoblasts

- osteoblasts in the peristeum start to secrete a layer of osteiod

- osteiod hardens and forms a periosteal bone colar around the shaft

Front 39

Step 3 of Endochondrial Ossification

Back 39

- primary ossification center forms in diaphysis

- remaining cartilage serve as a template on which osteoblasts begin to produce osteoid

Front 40

Primary Ossificaiton Center

Back 40

- region where bone replaces cartilage in the center of the diapysis of hylaine cartilage model

- development extends toward the epiphyses from the primary ossificaiton center

Front 41

Step 4 of Endochondrial Ossification

Back 41

- secondary ossification center froms in epiphysis

- hyaline cartilage in each epiphysis calcifies and degenerates

- oestoclats resorb some bone matrix, within the diaphyis accreating collwo medullary cavity

Front 42

Step 5 of Endodochondrial Ossification

Back 42

- bone replaces cartilage excapt the articular cartialge and epiphyseal plates

Front 43

Step 6 of Endodcondrial Ossfication

Back 43

- epiphyseal plates ossify and from epiphyseal lines

- epiphyseal plate exhibits five distinct zones

Front 44

Zone of resting cartilage

Back 44

- futhes from the medullary cavity of diaphysis and near epiphysis

- composed of chondrocytes and resembles mature healthy hyaline cartilage

- secures epiphysis to epiphyseal plate

Front 45

Zone of Proliferation Cartilage

Back 45

- chondrocytes undergo rapid mitotic cell division, enlarge, and become alligned into longitudinal colums of flattened lacunae

Front 46

Zone of Hypertrophic Cartilage

Back 46

- chrondrocytes cease dividing and enlarge greatly

- walls of lacunae become thin bc condrocytes resorb matrix during hypertrophy

Front 47

Zone of Calcified Cartilage

Back 47

- minerals are depostied in the matrix betq3een columns of lacune

- calfication kills condrocytes and makes matrix appear opaque

Front 48

Zone of Ossification

Back 48

- walls break down between lacunae colums, forming longitudinal channels

- spaces invaded by capillaries and osteoprogenitor cells

Front 49

Intersitital Growth

Back 49

- occurs within epiphyseal plate as chondrocytes undergo mitotic cell division in zone 2 and 3

- push resting cartilage toward epiphysis while bone is being produced in zone 5

Front 50

Appositional Growth

Back 50

- occurs within periosteum

- osteoblasts lay down bone matrix parallel to the surface called external circumferential lamella

- increase in lamellae increase in width

- osteoclasts along with medullary cavity resorb bone matrix creating an expanding medullary cavity

Front 51

Bone Remodeling

Back 51

- continual despostion of new bone connecitve tissue and the removal

- helps maintain calcium and phosphate in body fluids and can be stimulated by stress on a bone

- occurs at periosteal and endosteal surfaces

- changes the total amountof mineral deposited in the skeleton

Front 52

Blood Supply

Back 52

- blood vessels enter from the periosteum

- typical long bone has four set of major blood vessels

Front 53

Metaphyseal Blood Vessels

Back 53

- provide the blood supply to the diaphyseal side of the epiphyseal plate which is the resgion where new bone ossfication forms bone connective tissue to replace cartilage

Front 54

Epiphyseal Arteries and Veins

Back 54

- provide blood supply to the epiphyses of bone

Front 55

Periosteal Blood Vessels

Back 55

- provide blood to the external circumference of lamellae and the superifical osteons within the compact bone and external edge of bone

Front 56

Growth Hormone

Back 56

- produced by the anterior pituitary gland

- affect bone growth by stimulating the formation of another hormone stomatomedin which is produced by the liver

Front 57

Stomatomedian

Back 57

- directly sitmulates growth of cartilage in the epiphyseal plate

Front 58

Thyroid Hormone

Back 58

- secreted by the thyroid gland

- stimulates bone growth by influencing the basal metablic rate of bone cell

Front 59

Calcitonin

Back 59

- thyroid gland hormone that secretes in response to elevated levels of calcium in the blood

- encourages calcium depostion form blood into bone and inhibits osteoclasts activity

Front 60

Parathryiod Hormone

Back 60

- secreted realeased by the parathryiod gland in reponse to reduced calcium levels in the blood

- ultimately increases blood calcium levels so body tissue can utilize calium

- stimulates osteocalsts to resorb bone and increase calcium level in blood

Front 61

Sex Hormone

Back 61

- dramatically accelerate bone growth

- increase the rate of bone formation by osteoblasts in ossification centers within the epiphyseal plate

Front 62

Vitamin A

Back 62

- activiates osteoblasts

Front 63

Vitamin C

Back 63

- required for normal synthesis of collgen

Front 64

Vitamin D

Back 64

stimultes the absorption and transport of calcium and phosphate ions into the blood

Front 65

Stress

Back 65

- ability to increase amounts of mineral salts deposited and collagen fibers sythesized

- increase production of calitonin which helps inhibit bone resorption by ostoeclasts and encourage bone desposition by osteoblasts

Front 66

Stress Fracture

Back 66

- thin break caused by recent increased in physical activity in which it experiences repeptive loads

Front 67

Traumatic Fracture

Back 67

- result of impact or excess stress to the bone

Front 68

Pathologic Fracture

Back 68

- occurs in bone that has been weakend by disease

Front 69

Step 1 in Bone Fracture Repair

Back 69

1) hematoma forms form the clotted blood bc blood vessels are torn

Front 70

Step 2 in Bone Fracture Repair

Back 70

2) fibrocartilaginous callus forms

- fractue hematoma is reorganized into an actively connective tissue called procallus

- fibroblasts produce collagen fibers that help connect the brocken ends of the bones

- chondroblasts in the connective tisseu form a dense regular connective tissue associated with cartilage

- procallus eventually becomes a fibrocaritlaginous callus

Front 71

Step 3 in Bone Fracture Repair

Back 71

4) A hard callus forms

- osteoprogenitor cells adjacent to fibrocartilaginous callus become osteoblasts and produce trabeculae of primary bone

- fibrocartilaginous callus is replaced with hard callus

Front 72

Step 4 in Bone Fracture Repair

Back 72

- remodeling is the final stage

- hard callus stays for 3-4 months as osteoclats remove excess bony material from both exterior and interior surfaces

- compact bone replace primary bone