Bone/Cartilage Histo Lab Flashcards
Cartilage is a specialized type of
specialized type of connective tissue
composed of chondrocytes embedded in a firm gel-like ground substance or matrix containing fibrous macromolecules
is cartilage vascular or avascular?
AVASCULAR
what is the main function of cartilage?
to support soft tissue
what are other functions of cartilage?
-shock absoprtion
-friction-free sliding surfaces for joints
-model for long bones during development
-essential for growth of long bones during childhood
what are the three types of cartilage?
hyaline
elastic
fibrocartilage
chondrocytes
-major cell type in cartilage
- reside within lucunae
- secrete components of ground substance
- appear quiescent but continue to interact with cart. matix
-required to maintain molecular integrity of matrix
cartilage components
chondrocytes
ground substance (chondroitin, collagen II)
chondroitin
cartilage ground substance contains chondroitin which gives tissue elasticity and flexibility
what type of collagen is in cartilage?
Collagen II
does cartilage sense injury/damage?
no
it is aneural (no sensation to injury or damage)
functions of cartilage
-resist compression forces
-enhances bone resilience
-provides support on boney areas -where there is a need for flexibility
-acts as a “shock absorber”
what does cartilage derive from?
mesoderm
where is hyaline cartilage found?
trachea
bronchi
larynx
nose
articular bone surfaces
ventral ends of ribs
transient skeleton model
epiphyseal growth plate
where is elastic cartilage found?
auricle of the ear
Eustachian tubes
epiglottis
larynx
where is fibrocartilage found?
intervertebral discs
pubic symphysis
some ligaments
meniscus
hyaline cartilage objects of identification
chondrocytes
perichondrium
interterritorial matrix
territorial matrix
septum
lacuna
isogenous group
elastic cartilage objects for identification
chondrocytes
isogenous group
perichondrium
elastic fibers
fibrocartilage objects for identification
chondrocytes
annulus fibrosus
symphysis pubis
nucleus pulposis
Fibrocartilage characterisitcs
-matrix is rich in Type I collagen fibers (as in dense connective tissue)
-contains Type II collagen fibrils (characteristic of all types of cartilage)
-fibers are more abundant than the ground substance
-fewer cells than in the other types of cartilage: cells are aligned in long rows between bundles of collagen
-NO perichondrium
hyaline cartilage characteristics
This is hyaline cartilage, with the following characteristics:
-chondrocytes in isogenous -groups/aggregates
-more cells in isogenous groups
-no large fibers
-most hydrated matrix
-“glassy”, transparent look
Which is the predominant type of collagen found in cartilage?
Collage II
In which region of the epiphyseal plate is active cell division and matrix production most prominent during endochondral ossification?
Zone of proliferating cartilage
Zone of proliferating cartilage is characterized by
-active cell division and matrix production
-Chondrocytes in this zone undergo rapid mitosis, leading to the longitudinal growth of the bone during endochondral ossification
What histological feature distinguishes fibrocartilage from hyaline cartilage?
Fibrocartilage is distinguished by its ABUNDANT COLLAGEN I FIBERS
Cartilage ground substance:
-not mineralized
-texture is like very firm Jello®
-contains proteoglycans and
-responsible for:
–the stiffness of cartilage
–incompressibility
–flexibility (compared to bone)
bone components
bone cells
-osteoprogenitor (stem)
-osteoblasts (formation)
-osteoclasts (resorption)
-osteocytes (mechanosensing)
extracellular organic matrix
extracellular inorganic matrix
osteoprogenitor cells
Stem cells of bone
-retain the ability to re-differentiate into osteoblasts
-reside in the bone canals, endosteum, periosteum, and marrow
-regulate the influx and efflux of mineral ions into and out of the bone matrix
-responsible for the formation of bone remodeling compartments
osteoblasts
Bone forming bone cells
-regulate osteoclastogenesis and osteocyte formation
-synthesize and secrete:
- osteoid: bone matrix
-alkaline phosphatase to regulate bone mineralization
-nucleators for bone mineralization
–dentin matrix protein (DMP-1)
–bone sialoprotein
- calcium and phosphate binding proteins to regulate deposition of mineral:
–osteocalcin
–osteonectin
osteoclasts
bone resorbing cells
- multinucleated cells derived from mononuclear monocyte-macrophage cells
- secrete:
—-hydrogen ions: acidify the resorption compartment beneath osteoclasts to dissolve the mineral component of the bone matrix
—-tartrate-resistant acid phosphatase (TRAP) + cathepsin K enzyme
—digest the proteinaceous matrix
osteocytes
mechanosensing bone cells
90% of bone cells
- terminally differentiated
- reside within canalicular system
- express osteocalcin/bone matrix proteins
bone extracellular organic matrix components
Type I Collagen
glycoproteins
growth factors: osteocalcin, osteonectin, bone sialoptrotein
how much of the bone volume is extracellular organic matrix?
over 90% of bone volume
bone extracellular inorganic matrix minerals
Calcium (99%)
Phosphorus (85%)
Magnesium
Sodium
function of extracellular organic matrix of bone
gives form
provides resistance
extracellular inorganic matrix functions
strength
stiffness
resistance to compressive forces
what part of bone is hydroxyapatite?
bone extracellular INORGANIC matrix
skeletal functions of bone
- provides body support and attachment of muscles and tendons
- body movement
- organ protection from injury
- houses and protects the bone marrow within its cavities
- reservoir of minerals such as calcium and phosphate
extraskeletal functions of bone
- hematopoiesis (including lymphopoiesis, myelopoiesis and megakaryopoiesis)
- endocrine function: bone regulates
-systemic mineral metabolism
-glucose and energy metabolism
-embryonic brain development and adult brain function
embryology of bone
mesodermal germ layer and neural crest