Lecture 20 Flashcards
Cartilage and bone are specialized connective tissues called ________
Skeletal tissues
Skeletal tissues are rigid – primary function is _________
Structural support
Identify
Identify
Mammalian cartilages are typically ______
Avascular
ECM promotes diffusion – hydrated by _________ and strengthened by _________
Ground substance, collagens
What does ground substance contain
Glycosaminoglycans (GAGs) and
proteoglycans
What is the cartilage cell and what does it do
Chondrocyte, secretes and maintains ECM
What does the chondrocyte secrete
GAG’s, procollagens
Identify
Identify
Identify
Look/ ECM/ functions/ distribution of Hyaline cartilage
Look/ ECM/ functions/ distribution of Elastic cartilage
Look/ ECM/ functions/ distribution of fibrocartilage cartilage
What is a form of hyaline cartilage that degenerates with age
Articular cartilage
Early degeneration of articular cartilage shows what
Fibrillation
Progressive degeneration of articular cartilage causes what
Osteoarthritis
What is cauliflower ear from
Blunt force trauma to ear causes hematoma (blood pool) and separation of perichondrium from cartilage
When damaged, cartilage has ___________
Limited regenerative ability
What does a tear in the fibrocartilage annulus fibrosis cause
Herniated intervertebral disc
Facts about herniated intervertebral disc
Elastic cartilage thats damaged can turn into what
Cauliflower ear
Fibrocartilage thats damaged can turn into what
Herniated intervertebral disc
Mammalian bone is typically _________
with capillaries enclosed by a network of
_________
Vascularized, vascular canals
Unlike cartilage, bone has _________
High oxygen needs
Bone is mineralized which ______________ and acts as a ________________
Strengthens the skeleton, acts as a calcium store
The osteocyte maintains the ___________,
_________ ECM as needed
Mineralized ECM, depositing and resorbing ECM
Bone- Molecular exchange occurs through tiny
interconnected tunnels in ECM called
_______
Canaliculi.
Osteocytes extend processes into canaliculi to connect with neighbors for communication and ___________.
Exchange of nutrients and wastes
Identify arrows
What is an osteoprogenitor cell
Unipotent stem cell that replenishes osteoblasts
Osteoblasts, osteoclasts, and osteoprogenitor cells occur where
On the periosteum (outside) and endosteum (internal surface)
Identify types of cells
What do osteoblasts do/ what can they become
What is a bone-lining cell
Flat and inactive
What do osteoclasts do
Identify
Bone ECM is secreted one layer at a time
primarily by _________
Osteoblasts
The organic portion of bone ECM consists
mainly of what
Type I collagen fibers
The organic ECM is pale before
mineralization and is called what
Osteoid
Identify
____________ is the mineral part of bone ECM and is added to the osteoid
Hydroxyapatite
Osteoblasts secrete _______ to concentrate calcium ions in the osteoid
Osteocalcin
Osteoblasts then release _______, which crystallize hydroxyapatite around the collagen fibers
Matrix vesicles
Matrix vesicles contain _________, which is a marker for bone ECM formation
Alkaline phosphatase
How do osteoclasts decalcify the ECM
By lowering the pH with proton pumps
Byproducts of resorption (e.g., calcium ions) are endocytosed by the osteoclast and secreted where
Into blood capillaries
A _______ is evidence of prior osteoclastic activity – resorptive cavity
Scalloped surface
Hyperactivity of osteoclasts can lead to what
Low bone mass like osteoporosis
Identify
Identify
What does woven bone represent
Woven bone shows disorganized
cells and ECM, Woven bone reflects fast growth
(e.g., fetal growth, fracture repair)
What does lamellar bone represent
Lamellar bone shows layering of
cells and ECM (layer=lamella), Lamellar bone reflects slow growth
Where does red marrow live
Medullary cavity
Identify the parts of bone
What is the embryological origin of bone
Lineages of neural crest cell, paraxial mesoderm, and lateral plate mesoderm give rise to bones
_________ condenses from neural crest cell and
mesoderm lineages
Mesenchyme (embryonic CT)
In humans, what are the 2 ways that bones can develop from mesenchyme?
Intramembranous ossification, endochondral ossification
Intramembranous ossification – mesenchyme develops under __________ into bone without cartilage precursor
High oxygen tension
Endochondral ossification – mesenchyme develops _______________. When the cartilage is vascularized, it is replaced by bone.
Hyaline cartilage model under low oxygen tension
Identify- Intramembranous ossification
Identify- endochondral ossification
Cartilage model formed initially under low oxygen tension is replaced in steps:
Midshaft perichondrium transforms into periosteum
Vascular invasion and formation of primary center of ossification in diaphysis
Vascular invasion and formation of secondary centers of ossification at epiphyses
What are the 2 kinds of growth that cartilage uses
Appositional growth and interstitial growth
In appositional growth, the dense CT
perichondrium that surrounds hyaline and
elastic cartilage _______________ and
ECM to the surface of the cartilage
Adds new chondrocytes
In interstitial growth, a chondrocyte divides
into a cluster of ___________ called __________. The daughter cells move apart from each other as they secrete ECM, increasing tissue volume from within
Daughter cells called an isogenous group
Bone is mineralized, so it can only increase in volume by _______
Appositional growth
What lines the external surface of bones
Periosteum
What lines the internal vascular cavities of bone
Endosteum
Periosteal apposition ________ the bone
Widens (thickens)
Endosteal apposition _________
Infills the bone (converts cancellous to compact)
Major damage: fracture healing
Minor damage: microfracture repair
Increased apposition relative to resorption leads to _____________
High bone mass and brittleness
Decreased apposition relative to resorption leads to _____________
Low bone mass and weakness
What is a major diagnostic sign of Paget’s disease
Osteons with poor lamellae and wavy reversal lines
What is the cause of Paget’s disease
Disorganized bone remodeling caused by accelerated resorption and apposition
C
D
