4 - Dougherty - Cartilage, Bone, and Bone Growth

Question 1

Major two components of cartilage matrix?

Major components of cartilage fibers?

Answer 1

Hyaluronic Acid

Glycosaminoglycans (GAGs)

Collagen +/- Elastic Fibers

Question 2

Hyaline:

Locations

Answer 2

Developing skeleton of embryo (templates)

Epiphyial plate (“growth plates”) of growing bones

Articular cartilage (heads of bones, lower friction)

Respiratory Tract

Question 3

Elastic Cartilage:

Locations

Answer 3

Ear

Epiglottis

Eustachian Tube

Question 4

Fibrocartilage:

Locations

Answer 4

Intervertebral Disks

Meniscus of Knee

Mandible

Sternoclavicular Joints (clavicle/sternum jx)

Pub Symphysis (between pelvis)

Question 5

How do cartilage get nutrients?

Answer 5

They are avascular–receive nutrients from surrounding materials

Question 6

Chondroblasts

v

Cindrocytes

Answer 6

Condroblasts are still dividing, condrocytes are not dividing and located in the territorial matrix

Question 7

Hyaline Cartilage

Answer 7

Type II Collagen

Smooth surface for joints

May or may not have pericondrium

Question 8

Growth of Cartilage:

Appositional

v

Interstitial

Answer 8

Appositional: Cells from inner layer of perichondrium differentiate into chondroblasts (outer)

Interstitial: Growth of chrondroblasts by mitosis within the cartilage matrix (center)

Interstitial is INNER

Question 9

Elastic Cartilage

Answer 9

Type II Collagen

Elastic fibers add flexibility

Perichondrium surrounds

Question 10

Fibrocartilage

Answer 10

Type I and Type II Cartilage

Cells in rows

No perichondrium

Question 11

Cartilage X-ray properties?

Answer 11

Radiolucent or black

Question 12

Organic Components of Bone:

?

Inorganic Components of Bone:

?

Answer 12

Organic:

Osteoid:

Type I Collagen Fibers

Proteoglycans

Non-collagenous proteins (Osetopontin, Osteocalcin)

Inorganic:

Hydroxyapatite (Calcium phosphate)

Question 13

Non-collagenous proteins of bone?

Answer 13

Osteopontin

Osteocalcin

Question 14

Parts of Long Bone?

Answer 14

Epiphysis - Proximal/Distal ends, adjacent to physis (growth plate) or its remnants

Metaphysis - Adjacent to growth plate where bone deposition occurs

Diaphysis - Shaft, medullary cavity with marrow

Question 15

Compact Bone

v

Cancellous (spongy, trabecular) Bone

Answer 15

Compact: Dense, outside of long bones, lamellae (osteons)

Found in cortex

Cancellous (spongy, trabecular): Marrow cavities, trabeculae increase surface area

Found in medulla (center)

Question 16

Flat Bone

v

Long Bone

Answer 16

Flat bones are found in areas like the skull

Formed via Intramembranous (direct in mesenchyme)

- - -

Limb bones etc

Formed via Endochondral (cartilage templates)

Question 17

Osteon (Haversian System)

What are partial Osteons called?

Answer 17

Usually run lengthwise in long bone

Rings surrounding Haversian canal and canal itself for capillaries to supply blood

BLOOD SUPPLY

- - -

Interstitial Lamellae are partial osteons, an remnants from remodeling

Question 18

Volkmann’s Canal

Answer 18

Runs transverse along long axis of bone, carry capillaries that interconnect Haversian capillaries, or carry capillaries from periosteum

Question 19

How is bone prepared for analysis?

Answer 19

Ground: Ground down, dipped in ink (Osteons)

Decalcified: Weak Acid, (Cells)

Question 20

Answer 20

Question 21

What type of bone is this?

(also fill in blanks)

Answer 21

Cancellous Bone

Question 22

Osteoclasts

Answer 22

Consume bone (release Calcium to blood stream)

Acidic H+-ATPase

Multinucleated/Monocyte Lineage

Question 23

Osteoprogenitor Cells

Answer 23

Stem cells that give rise to osteoblasts, found in lining of periosteum and endosteum

Question 24

Osteocytes

Answer 24

Trapped Osteoblasts

Reside in lacunae

**Highly branched via canaliculi (connected via Gap Junctions)**

Question 25

Periosteum v Endosteum

Answer 25

Periosteum = outer later, can be "peeled" up by infection/tumor Endosteum = **lines inner bony surfaces**

Question 26

Intramembranous Bone Formation

Answer 26

**_Flat_** bones Forms directly in mesenchyme Skull, mandible, clavicles **_WIDENS LONG BONES_**

Question 27

Endochondral Bone Formation

Answer 27

Forms **Cartilage** template **Long** bones **_LENGTHENS Long Bones_**

Question 28

What is the common starting point for intramembranous and endochondral bone formation?

Answer 28

Forming trabeculae of spongy bone

Question 29

Endochondral Ossification: Starting Point? Locations? Primary/Secondary? What other Growth Mechanism plays role?

Answer 29

Starts from **HYALINE CARTILAGE** **- - -** Limbs, Vertebrae, Pelvis - - - Primary = Diaphysis Region Secondary = Epiphysis Region - - - **Intermembranous** thickens bone in center

Question 30

What occurs to chrondrocytes as matrix calcifies in endochondral bone formation?

Answer 30

Chondrocytes undergo apoptosis as matrix calcifies

Question 31

Woven Bone v Lamellar Bone

Answer 31

Woven: **Comes FIRST**, random orientation, less mineralization - - - Lamellar: **Regular formation**, collagen fibers, spiral bundles

Question 32

Type of Bone?

Answer 32

Woven - Random Collagen deposition - Rapid, observed following fracture - **Pathologic** in adults

Question 33

Type of Bone?

Answer 33

Lemallar Bone - Ordered collagen - Replaces woven bone, stronger - Notice uniform collagen lines

Question 34

Where does all increase in length take place after ossification of the cartilage template is complete? How does width increase?

Answer 34

At the Epiphyseal plate - - - Width increase occurs by apposition (intermembranous) growth from **periosteum and resorption of bone at the endosteum**

Question 35

Osteopetrosis v Osteoporosis

Answer 35

Petrosis = **reduced osteoclast** (too much bone) Porosis = **high clast/low blast** (brittle bones)

Question 36

Normal on right, what on left?

Answer 36

Osteopetrosis - See lack of cortex on left

Question 37

Steps to Bone Repair

Answer 37

1 - Hematoma @ fracture 2 - Fibrocartilaginous (soft) callus (**cast here**) 3 - Hard (bony) Callus - Woven Bone 4 - Lamellar Bone, Remodeling