Cartilage Flashcards
What is the developmental origin of cartilage?
mesenchyme
What are 4 ways cartilage differs from bone?
- bone matrix can become mineralized. If cartilage becomes mineralized, it will degrade
- Cratilage is avascular while bone is highly vascular
- Cartilage lacks innervation
- Cartilage growth is appositional and interstitial while bone growth is only appositional
What are the two cell types in cartilage?
chondroblasts
chrondocytes
Where are the cells located?
within lacunae
Why do the cells in cartilage have few mitochondria?
they’re primarily anaerobic
What are the components of the ground substance in cartilage?
60-80% is water
proteoglycan: aggrecan (chondroitin sulfates and keratan sulfates covalently bound to protein backbone - all linked with hyaluronate into aggregates)
What protein linkes aggrecan together to form proteoglycan aggregates? What does this doe for the cartilage?
hyaluronate
it’s extremely hydrophilic so that the cartilage will bind water and become a stiff gel
What glycoprotein adheres the chondrocytes to type II collagen?
chondronectin
What are the two main types of fibers in cartilage?
collagen
elastin for elastic cartilage only
How are the collagen fibers arranged in general in cartilage?
they’re NOT bundles into large fibers - microfibrillar
so its sometimes hard to see them because they have a similar refractive index as the ground substanc.
WHat are the three types of cartilage?
hyaline (most common)
Elastic
fibrocartilage
Where is hyaline cartilage located int he body?
fetal skeletal
epiphyseal plate in children
nose, larynx, trachea, ribs articular cartilage
What type of collagen is in hyaline cartilage?
type 2
What is the outer layer of hyaline cartilage? What cells are located there?
It’s called the perichondrium
In the fibrous layer there is fibroblasts and in the chondrogenic zone there are chondroblasts
Where are the chondrocytes located in hyaline cartilage?
in lacunae, surrounded by intercellular substance
Where is the perichondrium lacking?
on articular surface of articular cartilage
How does hyaline cartilage gets its nutrients and remove its waste?
through diffusion (this is why mineralization is bad for cartilage - it prevents diffusion)
What do you call it when a chondroblasts multiplies within a lacuna?
it becomes an isogenous nest
What is the difference between appositional growth and interstitial growth?
appositional growth is the addition of chondroblasts onto the surface of the cartilage
interstitial growth is mitototic activity of chondrolasts and ormation of isogenous nests to synthesize the matrix from the inside of the cartilage
Why is regeneration of damaged cartilage difficult?
it’s avascular
Where is elastic cartilage located?
the pinna of the ear, eustachian tube, and external auditory canal
epiglottis and some laryngeal cartilage
What type of fibers are in elasti cartilage?
elastic fibers and some type 2 collagen
True or false: elastic cartilage has a higher density of cells/isogenous nests than hyaline cartilage.
true
What is the outer layer of elastic cartilage called (again)?
perichondrium
Where is fibrocartilage located?
intervertebral disks and pubic symphysis
tendon and ligament attachments
What type of collagen is present in fibrocartilage?
type 1
In comparison to the other 2 types, does fibrocartilage have more or less ground substance? How about cells perunit area?
it has less ground substances and fewer cells
True or false: fibrocartilage has a perichondrium.
false
What happens in achondroplasia?
it’s a hereditary disease that reults in the failure of chondroblasts proliferation in epihphyseal plates, so you get premature fusion of epiphysis with the diaphysis resulting in dwarfism - small limbs
How is a herniated disc a pathology of cartilage?
the annulus fibrosis is fibrocartilage that can become weak with age, allowing the nucleus pulposus to leak through.
