what is cartilage?
specialized connective tissue
contains extracellular matrix enriched with
-glycosaminoglycans
-proteoglycans
these bind with collagen and elastic fibers
types of cartilage
-what determines differences?
hyaline cartilage elastic cartilage fibrocartilage determination -compositional differences
hyaline cartilage
-locations
epiphyseal plate
articular surfaces
walls of trachea
elastic cartilage
-locations
epiglottis
cuneiform cartilage
auricle
fibrocartilage
-locations
intervertebral disc
pubic symphysis
acetabular labrum
cartilage functions
shock absorber
provides smooth surface for sliding area of joints
development and growth of long bones
cartilage composition
cells (chondrocytes) with lacunae
extracellular matrix
-fibers
-ground substance
matrix composition of cartilage
collagen
hyaluronic acid
proteoglycans
“other” glycoproteins - chondronectin
what gives cartilage its stiffness?
hydrostatic bonds of the glycosaminoglycan chains of the proteoglycans
cartilage
- vascularity
- how does it obtain nutrients
cartilage is avascular
nutrients supplied by diffusion through the matrix
-either by vascularization within the Perichondrium
-or by synovial fluid (for articular (hyaline) cartilage)
what is the perichondrium
capsule of dense connective tissue surrounding the cartilage
hyaline cartilage
-what type of collagen?
collagen type II
perichondrium
- what type of tissue
- contains
- inner cellular layer (chondrogenic cells) becomes…
dense connective tissue (irregular)
contains type I collagen with fibroblasts
inner layer is adjacent to cartilage and becomes chondroblasts
chondroblasts become ___ when enclosed in cartilage
chondrocytes
chondrocytes
- appearance
- may be a number of chondrocytes in _____ due to mitotic activity
appearance
-elliptical at edge of developing cartilage
-round once fully enclosed in cartilage matrix
may be in lacunae
hyaline cartilage growth is dependent upon…
somatomedin C from the liver
produces as a result of somatotropin from the pituitary gland
how does growth occur in cartilage?
interstitial growth
appositional growth
interstitial growth
-characteristics
mitotic division of chondrocytes
evident developmentally - 1st formation
growth plate - increases length of bone
articular surfaces - due to lack of perichondrium
appositional growth
-what does it do?
increases girth
elastic cartilage
- location
- types of fibers
- abundant in ____ and they are ____ than in hyaline cartilage
location -outer layer of perichondrium fiber types -type II collagen -elastic fibers more abundant in chondrocytes -larger than in hyaline
fibrocartilage
- associated with…
- type of fibers
- perichondrium
- chondrocytes
associated with dense connective tissue fibers -collagen type I no perichondrium chondrocytes arranged in rows (isogenous groups)
bone
-functions
structural -support and series of levers for movement protection of vital organs -skull, thoracic cage, vertebral column storage pool for Ca2+ and PO4-
periosteum
-contains
outer dense connective tissue layer
inner cellular layer with osteoprogenitor cells
central cavity of bones
-contains
endosteum with osteoprogenitor cells and osteoblasts
bone matrix
glycoproteins and proteoglycans associated with collagen Type I hydroxyapatite -Ca2+ -PO4- -H2O
bone cell types
osteoprogenitor cells
osteoblasts
osteocytes
osteoclasts
osteoprogenitor cells
-function
differentiate into osteoblasts (or chondrogenic cells)
osteoblasts
- location
- function
- connected via…
line surface of bone
secrete matrix (osteoid)
connected via gap junctions
osteocytes
formed from osteoblasts
osteoclasts
- origin
- function
- type of border
- what is the area of bone matrix that has been removed called?
hematopoietic in origin function -bone resorption ruffled border -irregular surface facing bone removed bone matrix -Howship's Lacunae
types of bone
compact
spongy (trabecular)
regions of a bone
diaphysis -shaft epiphysis -articular ends metaphsis -area of spongy bone columns between epiphyseal plate and diaphysis
what separates epiphysis and diaphysis
epiphyseal plate
primary vs. secondary bone
primary
-formed embryologically (or as repair)
replaced by secondary bone
secondary bone characteristics when compared with primary bone
regular lamellae
more dense calcification over a more regular system of collagen fibers
osteon
- what is it?
- composed of
deep compact bone lying between inner and outer lamellae
composed of osteoblasts
-these are connected via caniliculi
these connected osteoblasts surround the central canal with the blood vessel
-this is called a Haversion canal
caniliculi
-function
connects osteoblasts in an osteon
gap junction between osteoblasts runs through here
Haversion canals (which run parallel to the bone’s longitudinal axis) are connected laterally via…
Volkmann’s canals
two types of bone growth
intramembranous
endochondral
intramembranous bone growth
-how does it occur?
osteoblasts secrete matrix that begins to form spicules
endochondral bone growth
-how does it occur?
hyaline cartilage model is encased by a subperiosteal bone collar (intramembranous)
-this bone collar deposits bone matrix
bone remodeling occurs as a result of…
growth and stresses on bone
bone repair requires…
adequate blood supply
proximity of opposing bone faces
mesenchymal cell
-what is it?
stem cell that has not committed to making any type of connective tissue
primary ossification site
shaft of bone - ossifies first
secondary ossification site
ends of bone
