Lec 3 Cartilage and Bone Flashcards
What are characteristics of cartilage ECM
How does it function
Highly specialized: abundant, firm, pliable, smooth and resilient
Covers surfaces of bones (articular) so the bones can slide against each other
Cartilage can withstand compressive forces - intervertebral discs
Explain cartilage innervation and flow
Cartilage is avascular, no lymphatics, no nerves
Can withstand force without pain or vascular damage, but heals slowly
Explain cartilage in terms of structure
Gives structure to soft tissues without being rigid
-trachea rings, larynx, pinna
Func in development of long bones
What are components of ECM of cartilage
THE ECM determines characteristics of cartilage
Rich in type 2 collagen fibers, other types less common
Rich in cartilage specific GAGs - chondroitin 4/6 sulfate, keratin sulfate)
- linked to core protein forming proteoglycan - AGGRECAN
Adhesive Glycoproteins - Chondronectin, bind cells and parts of the ECM
Upshot: Withstands tensile and compressive forces (GAG pulls water in)
What is chondrocytes function
produce, maintain fibres and organic products of GS - GAG and adhesive glycoproteins
How does cartilage get nutrients and gas
They are avascular and depends on gas/nutrient diffusion through GS from vessels
Metabolizes glucose by anaerobic glycolysis
Thus slow repair and thick cartilages are limited
How are mature chondrocytes found as
Isogenous groups - groups of daughter cells from a common parent/precursor cell
What kind of CT is cartilage surrounded by
And its func/ characteristic
Perichondrium - dense irregular CT
- forms the interface btwn cartilage and tissues
- for cartilage attachment and support
Has BVs, nerves and lymph nodes
Explain the layered struc of the perichondrium
2 Layers
- Outer fibrous layer: Dense irregular CT (collagen type 1 and fibroblasts) - this layer provides attachment to tissue
- Inner cellular layer: has chondroblasts making organic stuff of ECM - this func for cartilage growth
Explain interstitial growth of cartilage
Cartilage forms from mesenchyme (embryonic CT)
In places where cartilage is to form, mesenchymal cells diff into chondroblasts that will secrete organic components of into matrix (collagen 1 and 2)
Chondroblasts will surround themselves with matrix and separate from each other and are isolated in their lacunae
- this way they cant communicate
Chondroblasts can then divide creating isogenous groups that secrete matrix and grows apart - adding thickness to cartilage
What happens to isolated chondrocytes
They become quiescent (inactive, dormant) and maintain matrix as chondrocytes
Explain APPOSITIONAL growth of cartilage
Is growth at surface
Mesenchymal cells at surface cartilage start diff into fibroblasts, secreting type 1 collagen - forms fibrous layer of perichondrium
Mesenchymal cells deep to the fibrous layer diff into chondroblasts - forming the cellular layer of the perichondrium. SECRETES MATRIX ONTO NEW CARTILAGE SURFACE.
What are the 3 subtypes of cartilage and where are they found
Hyaline cartilage: Ribs (costal), Nose, Articular (shoulder), epiphyseal plates, fetal/immature skeleton
Elastic cartilage: Pinna, larynx, epiglottis
Fibrocartilage: intervertebral discs
How strong is hyaline cartilage
What is its function
Other characteristics
Weakest of the cartilage - Type 2 collagen in ECM along with gel like GS
Functions to resist compression, gives tough and flexible support, reduces friction
How come all hyaline cartilage structures are covered in perichondrium EXCEPT Articular cartilage
Articular cartilage no perichondrium so it cant get nutrients
Its missing perichondrium cause it need to contact another hyaline cartilage for smooth movement
What is Elastic cartilage function
How is it diff from Hyaline
Provides greater flexibility and resiliency (can recover from deformation) (compared to Hyaline)
Similar to Hyaline but with more elastic fibres
Has perichondrium