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Flashcards in Bone & Cartilage Deck (18):

-Connective Tissues - function & derived from

-ECM (components)

-Provide struct. & metabolic support for other tissues
-derive from mesenchyme (from embryonic mesoderm)
-ECM dominant functional & mechanical component - relatively aceullar

ECM: (Stroma) - bulk of tissue non-living material (produced by cell and assembled out of cell
Composed of: ground substand (fluid + proteoglycans), fibres & crystal (additional component in bone)

-Variable vascularity (bone = extensive; cartilage = none)


How ECM is produced

-3 types of cells that maintain ECM

-produced and maintained 'remotely' by local cell types;

-fibrocyte/fibroblast: fibrous tissues
-chondrocyte/condroblast - cartilage
-Osteocyte/osteoblast - bone

*ECM constantly turned over - most digested by specific enzymes (matrix metallopoteases - MMPs)
-esp. important for bone - would become too fragile due to microfractures


Types of connective tissues based on their ECM composition

-cartilage - why it is stiff

-Tendon: regular, large bundles of type 1 collagen
-long parallel arrays that provide excellent tensile strength in direction of fibres
-Cartilage: meshwork of type 2 collagen trapping massive sponge-like proteoglycans (have polar side that sucks water in - causes swelling & for them to get trapped n meshwork - is what makes cartilage stiff)
-firm but resilient and springy
-Bone: woven collagen sheets trap hard, calcified matrix (trap a lot of inorganic minerals)
-very hard but brittle


3 Types of cartilage that form skeleton

-definition of Perichondrium

1. Hyaline Cartilage (slightly transparent)
2. Fibrocartilage (opaque white - due to type 2 collagen)
3. Elastic Cartilage (little webs of elastin throughout)

Perichondrium: fibrous membrane that covers growing and non-articular cartilage


3 Functions of Cartilage

1. Provide structure or support for soft tissue
-i.e. airways (hyaline), pubic synapsis (fibrocartilage)
2. Form or assist articulations
-smooth surfaces where bones meet, joins bones together & shock absorbing pads
3. Precursor model for most bone growth
-serves as a "rough draft"


Types of Cartilage: Hyaline



-Where found

*most common & weakest
-clear glassy appearance under microscope
-chondrocytes w/in lucunae scattered through ECM
-collagen mainly in submicroscopic fibrils
-surrounded by perichondrium
-provides support through flexibility & resilience
-forms most of fetal skeleton & model for most future bone growth
-allows bones in joint to move
Found in: nose, trachea, most of larynx, coastal cartilage (attached to ribs), & articulate ends of long bones>


Types of cartilage: fibrocartilage



-Where found

*has numerous course, readily visible fibres in ECM
-fibres arranged as irregular bundles b/w large chondrocytes that are arranged in parallel rows
-sparse amount of ground substance
-collagen fibres interwoven = extreme durability
-no perichondrium (stress would destroy it)
Function: Acts as shock absorber and resists compression
Found: intervertebral discs, pubic symphysis & menisci


Types of Cartilage: Elastic



-Where found

-Numerous elastic fibres in ECM
-Fresh sections appear yellow
-chondrocytes closely packed & surrounded by small amount of ECM
-elastin fibres denser & more branched - from weblike mesh around chondrocytes w/in lucunae
-surrounded by periosteum
Function: Resists deformation
Found: epiglottis (larynx - stops swallowed materials entering trachea) & external ear



-cells w/in

-Composite (elements that make up bone don't have same properties as they do mixed together) structural tissue.
-collagen = flexibility & tensile strength
-calcium hydroxyapatite crystals = rigidity & compressive strength
-1/3 = organic (fibres & protein)
-2/3 = inorganic (Ca salts)
-rich blood & nerve supply
-continuous growth & remodeling due to stress
-OSTEONS (bony units) laid down by OSTEBLASTS, maintained by OSTEOCYTES, eaten away by OSTEOCLASTS


Compact bone vs. Spongy bone

Compact (aka cortical): appears solid, but perforated by vascular canals (usu. forms hard outer shell)

Spongy bone (aka trabecular, medullary, cancellous): w/in interior of bone - contains spaces (lattice structure) - is v. strong yet lightweight


Structure of Compact Bone

-solid & relatively dense
-made of cylindrical struct. called osteons that run parallel to bone
-contain concentric rings (lamellae) that encircle central canal
-lucunae b/w lamellae contain bone cells (osteocytes) that communicate w/ each other via blood vessels
-minute passages = canaliculi


Structure of Spongy Bone

-No osteons
-trabeculae composed of parallel lamellae
-between adjacent lamellae = osteocytes resting in lacunae - nutrients diffuse through canaliculi that open to surface of trabeculae (often form crisscross bars & plates of bone pieces)
-provide great resistance to stresses in many directions


2 Types of Ossification


-What bones they produce

*Ossification = formation & development of bone connective tissue (Begins in embryo & continues as skeleton grows - even happens into adulthood)
1. Intramembranous Ossification:
-develops from mesenchyme
-produces flat bones of skull, most facial bones, mandible & central portion of clavicle
2. Endochondral ossification:
-begins w/ a hyaline cartilage model
-Produces majority of bones in body


Regions of long bone

1. Diaphysis (shaft) - ossifies first
2. Ephiphysis (ends of bone) - ossifies second
3. metaphysis (between dia & epi)

*Epiphyseal Plate (aka Growth plate): where endochondral ossification continues to allow lengthening of a long bone


TERMINOLOGY: Articulating Surface


Condyle: Large, smooth, rounded articulate oval structure

Facet: small, flat, shallow articulating surface

Head: prominant, rounded epiphysis

Trochlea: smooth, grooved, pully-like articular process




Alveolus: Deep pit or socket in maxillae or mandible

Fossa: flattened or shallow depression

Sulcus: Narrow groove


TERMINOLOGY: Projections of tendon and ligament attachment


-Crest: narrow, prominent, ridgelike projection
-Epicondyle: projection adjacent to a condyle
-line: low ridge
-Process: any marked bony prominence
-Ramus: angular extension of a bone relative to the rest of the structure
-Spine: pointed, slender process
-Trochanter: massive, rough projection found only on femur
-Tubercle: small round projection
-Tuberosity: Large, round projection


TERMINOLOGY: Openings and spaces


-Canal: passageway through a bone
-Fissure: Narrow, slitlike opening through a bone
-Foramen: rounded passageway through a bone
-Sinus: cavity or hollow space in a bone