Exam 2 - Bone and Cartilage Flashcards
how does cartilage get nutrients
nutrients/waste pass to/from cell through matrix - avascular
what does cartilage contain
chondrocytes embedded in ECM
functions of cartilage
supports soft tissues, guides development/growth of long bones
where is hyaline cartilage located
at articular ends of long bones in adults, walls of respiratory system (nose, larynx, trachea, bronchi), ventral ends of ribs; also temporary skeleton for fetus until replaced by bone
type of collagen in hyaline cartilage
type 2
hyaline cartilage matrix
homogenous, amorphous ground substance w/ proteoglycan aggregates (w/ chondroitin, keratan sulfate, hyaluronic acid) and chondronectin embedded type 2 collagen + territorial/capsular matrix
where is territorial matrix found
adjacent to chondrocytes
composition of territorial matrix
low collagen, high GAGs
staining of territorial matrix
very basophilic and metachromatic; more intense with PAS stain than intercapsular matrix - due to sulfate groups on proteoglycans
perichondrium composition
dense irregular CT
perichondrium location
surrounds hyaline cartilage except at articular surfaces
perichondrium layers
outer fibrous layer and inner cellular layer
perichondrium function
provides blood supply for avascular cartilage
outer fibrous layer of perichondrium
type 1 collagen, fibroblasts, blood vessels
inner cellular layer of perichondrium
chondrogenic cells
what are chondrocytes
mature cartilage cells (chondroblasts that have been completely surrounded by matrix)
chondrocyte location
embedded in lacunae in matrix
chondrocyte function
maintain cartilage matrix
chondroblast function
produce cartilage matrix
isogenous groups
groups of 2-8 chondrocytes in the same lacunae
elastic cartilage composition
matrix w/ network of elastic fibers (yellowish color)
elastic cartilage location
where flexible support needed - external ear, Eustachian tube, epiglottis, larynx
elastic vs. hyaline cartilage degeneration
elastic less prone to degeneration
type of collagen in elastic cartilage
type 2
elastic cartilage perichondrium
similar to that of hyaline cartilage
fibrocartilage perichondrium
doesn’t exist
composition of fibrocartilage
alternating rows of fibroblast-derived chondrocytes and thick bundles of type 1 collagen fibers - properties b/w dense CT and hyaline cartilage
location of fibrocartilage
may align along lines of stress - found where support and tensile strength needed in conjunction w/ hyaline cartilage: IV discs, articular discs, pubic symphysis, tendon and ligament insertions, knee joint menisci
what is fibrocartilage easily confused with
dense regular CT
in general, what is bone
calcified ECM with osteocytes embedded in matrix
three main functions of bone
protects vital organs, supports fleshy structures, provides calcium reserve
how is bone dynamic
constant shape change, absorption, resorption in response to biomechanical forces
inorganic calcified portion of bone matrix
- contains calcium, phosphate, bicarbonate, citrate, magnesium, potassium, sodium
- primarily hydroxyapatite crystals
- minerals are 50% of dry weight
organic portion of bone matrix
mainly type 1 collagen with ground substance containing chondroitin sulfate, keratan sulfate
primary bone
immature, woven bone that is the first bone formed in fetal development and in bone repair
primary bone mineral content
lower than secondary bone
secondary bone
mature, lamellar bone - two types: compact, spongy
compact bone
dense, outer portion of bone with outer and inner circumferential lamellae and osteons around haversian canals
volkmann’s canals
connect osteons to each other
what is outer circumferential lamellae adjacent to
below periosteum
what is inner circumferential lamellae adjacent to
marrow cavity
spongy bone
meshwork of trabeculae in bone interior that helps distribute weight
spongy bone changes in osteoporosis?
becomes narrower
bone periosteum
layer of non-calcified CT covering bone on external surfaces, except synovial articulations, w/ outer fibrous, dense collagenous layer and inner cellular (osteogenic) layer
bone periosteum function
distribute blood vessels to bone
sharpey’s fibers
type 1 collagen - attach periosteum to bone
haversian canals
hold blood vessels in the bone
canaliculi
microchannels b/w cells so cells can make contact w/ each other - have gap junctions
endosteum - what and where
thin specialized CT that lines marrow cavities
endosteum function
source of osteoprogenitor cells and osteoblasts for bone growth and repair
cement line
region where remodeling has occurred - highly mineralized line
osteoid
non-mineralized bone matrix laid down first by osteoblasts
osteoprogenitor cells
flattened/spindle shaped cells that can differentiate into osteoblasts
osteoprogenitor cell location
inner layer of periosteum and endosteal cells that line marrow cavity
osteoblast shape and function
cuboidal/polygonal shaped cells that secrete collagen, ground substance, osteoid - regulate mineralization of bone
osteoblast location
single layer of cells in regions where bone is being formed
osteocyte function
maintain bone matrix - to limited extent can both synthesize and resorb bone
osteocyte location
in lacuna
how do osteocytes communicate w/ each other/osteoblasts
via processes that extend through canaliculi
osteoclasts description and function
multinucleated, acidophilic, phagocytic cells that actively resorb bone by releasing lysosomes into extracellular space - seal off area, acidifies and secretes acid hydrolases that resorb bone
Howship’s lacunae
depression in bone created by osteoclast
osteoporosis
decrease in bone mass associated with normal ratio of mineral to matrix - due to decreased bone formation, increased bone resorption, or both
osteoporosis with old age
due to lower secretion of GH
osteoporosis in immobile patients
due to lack of physical stress on bone
osteoporosis in PMS women
due to lower estrogen secretion
osteomalacia
bone disorder due to calcium deficiency in adults - deficient calcification of newly formed bone and decalcification of calcified bone
osteomalacia and pregnancy
may be severe in pregnancy - calcium requirements of fetus may cause calcium losses from mom
Rickets
osteomalacia in children - mostly vitamin D deficiency, but calcium deficiency can contribute - deficient calcification in newly formed bone usually accompanied by deformation of bone spicules in epiphyseal plates - slow growth, deformation
Paget’s disease
osteitis deformans - dysfunctional bone remodeling leading to bone that is abnormal, enlarged, not as dense, brittle and prone to breakage
acromegaly
excessive pituitary growth hormone in adults - very thick bones in extremities and in parts of facial skeleton