11/17 Histo of Cartilage Flashcards
what are the tree types of cartilage
hyalin cartilage; elastic cartilage; fibrocartilage.
How is Cartilage different from CT proper?
Avascular; only one cell type peresent, the chondrocyte. Type II collagen present
Compare the Cells in CT proper and Cartilage
CT: (Fibroblasts, adipocytes, MOs, Mast cells, Lys, Plasma cells, granulocytes. Cartilage (Chondrocytes)
compare the fibers in CT proper and Cartilage
CT Proper ( Type I collagen, some type III, elastic variables) Cartilage (type II collagen, type i varies elastic variable)
Compare the Ground substance of CT proper and cartilage
- Both have lots of GAGs. 2. Both have lots of proteoglycans (Cartilage has lots of aggrecan found in hyaline.) 3. Adhesive glycoproteins: CT proper(fibronectin, laminin). Cartilage (chondronectin, as well as fibronectin and laminin.)
What is the stem cell origin of cartilage.
they are from mesenchymal stem cells.
What is collagen?
it is a family of proteins, ca. 30 different genes with about 25 different types of collagen but 90% of it is Type I
Describe Type I collagen
Helix of 3 alpha chains (alpha 1 and alpha 2): 33% glycine (about every 3rd residue) with proline and lysine that is made into prolyl hydroxylase and lysyl hydroxylase.
What is the neccessary component that is needed to make the hydroxylases out of proline and lysine to make collagen (proline and lysine hydroxylation)?
vitamin C and oxygen in order to perform the hydroxylase reaction with proline and lysine
How does the reaction that is usd to make collagen used to control oxygen?
the reaction with vitamin C to make the hydroxylates also uses oxygen and so it can be a mechanism for sensing normoxia and hypoxia
What is the general chemical reaction that is needed to use amino acids to make collagen?
hydroxylation!
What if I don’t ever eat Vit. C what will happen
scurvy (general weakness, skin lesions, blood vessels fragility) where I can’t do hydroxylation of amin acid and cant make collagen.
Describe the construction of Collagen I fibers..
Tropocollagen is packed into overlaping layers that make alpha chains that are then wrapped together into fibrils, and then these are packed into fibers, and fibers are packed into bundles that make up structures such as tendons
How is Type II collagen structure different from type I?
it has tropocollagen layered into tropocollagen sheets that is wrapped into triples of alpha chains that are packed together to make fibrils (just like type I). Type II then stays as a fine mesh like structure of fibrils
How is type III different from Type I collagen construction
Associates into Fibers but not into bundles.
what gives hyaline cartilage matrix its high tensile strength and resiliency?
huge proteoglycan aggregates bind a considerable amount of water and ions, giving the matrix these properties.
the most widely dist. cartilage in the body
Hyaline cartilage
Hyaline cartilage found in…?
walls of large respiratory passages; larynx; articular surfaces of bones; ventral ends of ribs
Transient location of hyalin cartilage
model of skeleton, epiphyseal growth plate
Why would hyaline cartilage appear glassy and be strong and smooth?
it is type II collegen that is not fibers by a highly hydrated matrix!
Describe the contents of the Hyaline cartilage matrix
The proteoglycan aggregates, GAGs and Proteoglycans (e.g. AGGRECAN) along with: Bound water; and Type II collagen fibrils; and chondronectin that attaches cells to ECM, and finally Chondrocytes that turnover and replace matrix.
how much of the wieght of the hyaline cartilage would be water?
75-80%
What is the main fiber in hyaline cartilage matrix
Type II collagen fibrils (40-70% dry weight)
Attaches the cells to ECM in Hyaline cartilage…?
Chondronectin
What turns over and replaces the matrix of hyaline cartilage
the condrocytes do! proteoglycan turnover: weeks and type II collagen: years
the type of cartilage that is not surrounded by perichondrium
articular cartilage
The surrounding around most permanent hyaline cartilage
perichondrium
WHAT IS perichondrium made of?
Type I collagen fibers
the source of the progenitor cells for cartilage
the perichondrium is the source of chondrogenic cells (progenitors) and chondroblasts for growth of new cartilage and repair.
the progenitor cells of collagen
chondrogenic cells
What will supply the nutrients and remove waste in the cartilage?
the vasculature of the perichondrium…therefore limit thickness and repair
The cavities where the chondrocytes reside
the lacunae
The functions of Cartilage
Support soft tissue; shck absorber; low friction surface; model of skeleton
A group of Chondrocytes in the cartilage is what?
the cell mass in the lacuna is called a Cell nest or isoginous group.
the cartilage cells that come form the perichondrium
chondrogenic cells and chondroblasts
How do you get multiple chondrocytes clumped together in the cartilage.
the chondrocytes will undergo division and all of the cells in one lacuna are clones!
What do chondroblasts and young chondrocytes secrete?
ECM
The chondroblats move into the cartilage and become…
chondrocytes
The dark staining area around the lacuna in the cartilage
The territorial matrix
What is found in the territorial matrix in cartilage that makes it stain dark?
Rich in GAGs, stains darker
A dark staining streak inbetween chondrocytes in the lucana
Septum
The lighter colored area outside of the territorial matrix in a cartilage
The interterritorial matrix
What are the two types of cartilage growth?
Appositional growth and interstitial growth
What is appostitional growth
chondroblasts in perichondrium differentiate into chondrocytes, start producing matrix and add to existing cartilage.
what is interstitial growth
proliferation and hypertrophy of existing chondrocytes.
If the Articular cartilage does not have a perichondrium, then where does repair come form?
resident chondrocytes serve as progenitors but does not repair quickly at all.
where do we find articular cartilage?
Lines the joints…outside of it is the synovial fluid.
How do you identify elastic cartilage?
it will have elastic fibers, and has more cells then matrix…more cellular, but the isogenous groups have fewer cells per group.
Where would you find elastic cartilage
auricle of ear, eustachian tubes, epiglottis, larynx
how would you identify the fibrocartilage?
very little ground substance, mostly fibers, lots of type I collagen, along with type II; no perichondrium, fibrocartilage merges with adjacent tissue
What is the classic area of figrocartilage?
in the pubic symphysis…right up to and fused with the bone! and the intervertebral disks.
the components of intervertebral disks
It has hyaline cartilage on the body of the vertebra and then anulus fibrosus that is fibrocartilage; and in the middle is the nucleus pulposus.
What is the nucleus pulposus?
a liquid form of fibrocartilage, with more proteoglycans and water than in the annulus fibrosus.
Describe the composition of fibrocartilage in the pubic symphysis if I zoom up close…
Chondrocytes surrounded by lots of collagen fibers in strands and bundles. Looks like purple spots and areas surrounded by red ropes!
