4 - Dougherty - Cartilage, Bone, and Bone Growth Flashcards
Major two components of cartilage matrix?
Major components of cartilage fibers?
Hyaluronic Acid
Glycosaminoglycans (GAGs)
Collagen +/- Elastic Fibers
Hyaline:
Locations
Developing skeleton of embryo (templates)
Epiphyial plate (“growth plates”) of growing bones
Articular cartilage (heads of bones, lower friction)
Respiratory Tract
Elastic Cartilage:
Locations
Ear
Epiglottis
Eustachian Tube
Fibrocartilage:
Locations
Intervertebral Disks
Meniscus of Knee
Mandible
Sternoclavicular Joints (clavicle/sternum jx)
Pub Symphysis (between pelvis)
How do cartilage get nutrients?
They are avascular–receive nutrients from surrounding materials
Chondroblasts
v
Cindrocytes
Condroblasts are still dividing, condrocytes are not dividing and located in the territorial matrix
Hyaline Cartilage
Type II Collagen
Smooth surface for joints
May or may not have pericondrium
Growth of Cartilage:
Appositional
v
Interstitial
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
Elastic Cartilage
Type II Collagen
Elastic fibers add flexibility
Perichondrium surrounds
Fibrocartilage
Type I and Type II Cartilage
Cells in rows
No perichondrium
Cartilage X-ray properties?
Radiolucent or black
Organic Components of Bone:
?
Inorganic Components of Bone:
?
Organic:
Osteoid:
Type I Collagen Fibers
Proteoglycans
Non-collagenous proteins (Osetopontin, Osteocalcin)
Inorganic:
Hydroxyapatite (Calcium phosphate)
Non-collagenous proteins of bone?
Osteopontin
Osteocalcin
Parts of Long Bone?
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
Compact Bone
v
Cancellous (spongy, trabecular) Bone
Compact: Dense, outside of long bones, lamellae (osteons)
Found in cortex
Cancellous (spongy, trabecular): Marrow cavities, trabeculae increase surface area
Found in medulla (center)
Flat Bone
v
Long Bone
Flat bones are found in areas like the skull
Formed via Intramembranous (direct in mesenchyme)
- - -
Limb bones etc
Formed via Endochondral (cartilage templates)
Osteon (Haversian System)
What are partial Osteons called?
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
Volkmann’s Canal
Runs transverse along long axis of bone, carry capillaries that interconnect Haversian capillaries, or carry capillaries from periosteum
How is bone prepared for analysis?
Ground: Ground down, dipped in ink (Osteons)
Decalcified: Weak Acid, (Cells)
What type of bone is this?
(also fill in blanks)
Cancellous Bone
Osteoclasts
Consume bone (release Calcium to blood stream)
Acidic H+-ATPase
Multinucleated/Monocyte Lineage
Osteoprogenitor Cells
Stem cells that give rise to osteoblasts, found in lining of periosteum and endosteum
Osteocytes
Trapped Osteoblasts
Reside in lacunae
**Highly branched via canaliculi (connected via Gap Junctions)**
Periosteum
v
Endosteum
Periosteum = outer later, can be “peeled” up by infection/tumor
Endosteum = lines inner bony surfaces
Intramembranous Bone Formation
Flat bones
Forms directly in mesenchyme
Skull, mandible, clavicles
WIDENS LONG BONES
Endochondral Bone Formation
Forms Cartilage template
Long bones
LENGTHENS Long Bones
What is the common starting point for intramembranous and endochondral bone formation?
Forming trabeculae of spongy bone
Endochondral Ossification:
Starting Point?
Locations?
Primary/Secondary?
What other Growth Mechanism plays role?
Starts from HYALINE CARTILAGE
- - -
Limbs, Vertebrae, Pelvis
Primary = Diaphysis Region
Secondary = Epiphysis Region
Intermembranous thickens bone in center
What occurs to chrondrocytes as matrix calcifies in endochondral bone formation?
Chondrocytes undergo apoptosis as matrix calcifies
Woven Bone
v
Lamellar Bone
Woven: Comes FIRST, random orientation, less mineralization
Lamellar: Regular formation, collagen fibers, spiral bundles
Type of Bone?
Woven
- Random Collagen deposition
- Rapid, observed following fracture
- Pathologic in adults
Type of Bone?
Lemallar Bone
- Ordered collagen
- Replaces woven bone, stronger
- Notice uniform collagen lines
Where does all increase in length take place after ossification of the cartilage template is complete?
How does width increase?
At the Epiphyseal plate
Width increase occurs by apposition (intermembranous) growth from periosteum and resorption of bone at the endosteum
Osteopetrosis
v
Osteoporosis
Petrosis = reduced osteoclast (too much bone)
Porosis = high clast/low blast (brittle bones)
Normal on right, what on left?
Osteopetrosis
- See lack of cortex on left
Steps to Bone Repair
1 - Hematoma @ fracture
2 - Fibrocartilaginous (soft) callus (cast here)
3 - Hard (bony) Callus - Woven Bone
4 - Lamellar Bone, Remodeling
