Introduction to bone and cartilage Physiology Flashcards
What is Cartilage?
-highly hydrated tissue reinforced with variable amounts of collagen type II
_Its extracellular matrix (ECM) is:
60-80 % water
15 % collagen (type II)
9 % proteoglycans
*aggrecan – hyaline & elastic cartilage & hyaline matrix part of fibrocartilage
*Versican – multiple tissues including fibrocartilage (fibrous part)
5 % multiadhesive glycoproteins
How is cartilage formed?
- Aggregan & hyaluronate form proteoglycan aggregates
2.Aggrecans attach through their core protein to linear hyaluronic acid molecules
describe the result of the Interaction between type II collagen fibrils and proteoglycans in hyaline & elastic cartilage matrix
Physical properties of these matrix components produce a highly hydrated, pliable material with great strength.
Movement of large molecules limited, but metabolites and small mole
Unlike other connective tissues, there are no_____________ in the extracellular matrix. So how does cartilage receive nutrition?
- blood vessels (or lymphatics)
-THROUGH DIFUSSION
What does the development of cartilage look like?
What is perichondrium?
Mesenchymal cells immediately surrounding matrix becomes perichondrium
next to perichondrium is chondoblasts and with fluid farther away are CHONDROCYTES
What type of cells cover most cartilage?
Perichondrium covers most cartilage
What is the job of chondrocytes in the cartilage?
Chondrocytes produce, maintain, & repair the matrix
mitotically active
what are the two processes that cartilage can grow by?
Appositional growth occurs in the perichondrium
What are the areas of chondrocyte cell division?
Isogenic clusters
What are the three main types of cartilage?
what are the characteristics of hyaline cartilage?
Most common type of cartilage
Grossly looks white and translucent
Matrix often stains light blue with H&E
Matrix stains purple to reddish-purple with toluidine blue (sulfate groups in aggregan)
Appositional & interstitial growth
STAINS WITH TOLUDINE BLUE
where is hyaline cartilage located?
Fetal skeleton
Synovial articular surfaces
Epiphyseal plates (growth plates)
Larynx
Nasal cartilage
Trachea & Bronchi
What are the characteristics of elastic cartilage? and what is its location?
-elastic fibers predominant (fibers can only be seen with special stain)
-chondrocytes are larger than in hyaline (APPOSITIONAL AND INTERSITIAL GROWTH)
_location:
external ear (pinna)
auditory tube
epiglottis
apart of lyrengeal cartilage
What are the characteristics of fibrocartilage? and what stains recognizes it?
Foci of light blue hyaline cartilage matrix
*Chondrocytes in lacunae
*Single cells or isogenous groups (INTERSITIAL GROWTH ONLY)
Relatively parallel bundles of type I collagen
*Fibroblast – type cells
NO PERICHONDRIUM – therefore no appositional growth
-highly hydrated
-has collagen type II fibers
-develops from mesenchyme
What type of collagen makes up most of the organic material of BONES?
collagen type 1
What are the two types of histological preparations of bone tissue?
Decalcified bone section
ground bone section
What are the types of cells present in bones? and where are these located?
OSTEOBLASTS (plump) (Ob)
*Produce bone matrix proteins (OSTEOID-bone matrix)
*Trigger mineralization through secretion of alkaline phosphatase into matrix
ALKALINE PHOSPHATE controls rate of mineralization
OSTEOCYTES(Oc)
*Maintain bone matrix in which they are embedded
*Communicate with others via gap junctions
What are bone-lining cells? and where are they common?
Derived from osteoblasts – no longer synthesizing osteoid
Flat spindleoid cells, coving bone that is not remodeling
ADULTS
What are osteoclasts? what is their task?
A multinucleated cell derived from fusion of blood monocytes
RE-ABSORB BONE MATRIX
*Secretion of acid to demineralize matrix
*Secretion or proteolytic enzymes to breakdown collagen
The first bone formed at ANY SITE is woven (or primary) bone
greater proportion of osteocytes to matrix compared to mature (lamellar) bone
Seen in early embryo, at fracture site, o
Woven bone is soon replaced by ____________-
mature lamellar bone
Mature lamellar bone: collagen fibers have been re-modelled to become more parallel - in layers.
Much stronger
Predominant bone in adults
Classification of Bone Based on its Architecture
_Compact
*Very strong and dense
_Cancellous (aka Spongy, Trabecular)
*Honey comb arrangement (i.e. spaces between boney trabecular arrangement)
Spongy (a.k.a. cancellous) bone has boney spicules or trabeculae
flip
Cancellous bone is initially laid down as woven bone before becoming lamellar
What is the structure of compact bone?
-The osteon is the basic structural unit of compact bone
Cylinder composed of 4 to 20 concentric lamellae of osteoid arranged around a central opening, the osteonal canal
*A.k.a. central canal
*A.k.a. Haversian canal
Each osteon extends the length of the anatomic bone
Between the lamellae are entrapped osteocytes in lacunae (dark slit like openings)
Blood vessels & nerves travel through central canal
