Bones, Cartilage & Joints 1 Flashcards
what are the different types of connective tissue
what cells are in cartilage
chondroblasts –> produces the matrix
chondrocytes –> same cell that contains matrix
what is the extracellular matrix (ECM) in cartilage
unique biomechanical properties
fibres (depends on type of cartilage) –> rigidity
ground substance (abundant) –> resiliency
generally avascular (cells are reliant on diffusion for nurishment)
what are the 3 types of cartilage
- hyaline
- elastic
- fibrocartilage
what type of cartilage is this
hyaline
what type of cartilage is this
elastic
what type of cartilage is this
fibrocartilage
what is the most common type of cartilage
hyaline cartilage
what makes up hyaline cartilage
abundant ground substance plus few type II collagen fibres
what does hyaline cartilage form in the embryo
temporary skeleton in embyro –> gradually replaced by bone
responsible for growth of long bones
where is hyaline cartilage in adults
limited distribution
ex. articular surface of moveable joints, walls respiratory passages, costal cartilage (trachea)
how does hyaline cartilage grow
appositional and interstitial growth –> added to outer surfaces and growth within (unique to cartilage, bone is only appositional)
where is elastic cartilage found
ear pinna, epiglottis
what is in elastic cartilage
high content of elastic fibres + collagen type II
less ground substance
how does elastic cartilage grow
appositional and interstitial growth
where is fibro-cartilage found
limited distribution
inter-vertebral discs
intra-articular discs (menisci)
attachment ligament and tendons to bones
how is fibro-cartilage arranged
cells (chondroyctes) arranged in columns between bundles of collagen (type I)
minimal ground substance
no identifiable perichondrium (no CT between them)
how does fibro-cartilage grow
interstitial growth only (no bounding surface to allow growth from surfaces)
what is appositional growth
process begins with perichondrium (fibroblasts-chondroblasts synthesis matrix–> chondrocytes)
growth continues at the edges of a pre-existing cartilage model
what is interstitial growth
occurs within existing
chondrocytes become chondroblasts
isogenous groups form and produce mroe extracellular matrix
what are the cells
P- perichondrium
Cg- chondrogenic zone
Cb- chondroblasts
C- chondrocytes
what type of growth is shown here
green - appositional
red - interstitial
what is an example of hyaline cartilage where only interstitial growth occurs
articular cartilage and synocial joints
what is the origin of synovial fluid
synovial membrane or synovium –> specialized connective tissue with secretory capacity
what is the intima
2-4 cells deep
type A macrophage - maintenance and “clean up”
type B fibroblast (synoviocytes) - secretes hyaluronan (hyaluronic acid)
what is subintima
loose connective tissue
capillaries –> important for maintenance of articular cartilage which is avascular
what are the 3 components of synovial fluid
- interstitial fluid - blood plasma
- hyaluronan - fibroblast-like cells in the synovial membrane (synoviocytes)
- lubricin (proteoglycan 4; PRG4) - chondrocytes
what is the function of synovial fluid
fills the gap
- lubrication
- shock absorption
- nutrient transport
how does synovial fluid lubricate
forms lubricating film forms on synovial membrane and seeps into articular cartilage and spaces
squeeze film –> weeping lubrication –> fluid held in the cartilage is squeezed out mechanically to maintain a layer of fluid on the cartilage surface
how does synovial fluid provide shock absorption
becomes thick and viscous returning to normal viscosity
how does synovial fluid aid in nutrient transport
most articular cartilage in close apposition to synovial membrane
what are the functions of bone
- rigid and hard support
- protects vital organs
- contains bone marrow (hematopoiesis)
- reservoir for calcium, phosphate and other ions
- transforms forces of skeletal muscle contraction into bodily movements
what is the structure of bone
cells and fibres embedded in hard unbending calcified matrix
how is bone different than cartilage
dynamic tissue –> capable of remodelling and repairing itself –> unlike cartilage it is very vascular –> nourish cells
what are the 3 structures of bone
- epiphysis
- metaphysis
- diaphysis
what is compact bone
compact bone forms the outer wall
what is trabecular bone
interior of bone
what is another name for trabecular bone
spongy or cancellous bone
what are the types of lamellar bone
compact and trabecular
what are the structures
what is lamellar bone
specific orientation of collagen fibres –> biochemical function
what are the two types of lamellar bone
- compact (cortical) bone: diaphysis
- spongy, cancellous or trabecular bone: spicules are aggregated into bony trabeculae (plates)
what is woven bone
random orientation collagen fibres
temporary form association developing bone, fracture repair, bone tumours
replaced by lamellar bone in most cases
what is the basic unit of compact (cortical) bone
osteone or haversian system
what are the bone cell types
- osteoblasts
- osteocytes
- osteoclasts
what are osteoblasts associated with
periosteum/endosteum which covers external and internal
where are osteoblasts found
surfaces all bony surfaces
what is the function of osteoblasts
function is to form osteoid (organic part of ECM)
become osteocytes - maintenance
where are osteocytes
located within calcified “osteoid” ECM
what is the function of osteocytes
communicate with each other by special cellular extensions –> canaliculi
maintain the bony matrix
where osteoclasts
located on external and internal surfaces of boney surfaces
what are the characteristics of osteoclasts
large, motile, multinucleated cells
what is the functions of osteoclasts
characteristic ruffled border
enzymatic digestion of ECM –> important for remodelling of bone
name these cells
osteocyte - maintiains bone tissue
osteoblast - forms bone matrix
osteogenic cell - stem cell (osteoprogenitor cell, associated with periosteum or endosteum)
osteoclast - resorbs bone
what is the organic component (osteoid) of the bone ECM produced by
produced by osteoblasts
fibres - predominantly collagen type I (spiral arrangement)
when does the inorganic component of bone ECM form
after the osteoid laid down
hydroxyapatite crystals
Na, Mg, Fe
how is the calcified matrix impermeable
all connected through extensions surrounded by hard bone
the lacunar-canalicular system allows osteocytes embedded within the matrix to communicate with each other
what cartilage is responsible for growth of long bones
identify the histological cells of trabecular bone
what is shown here
calcified matrix very impermeable
lacunar-canaluclar system allows osteocytes embedded within the matrix to communicate
