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155 Cards in this Set
- Front
- Back
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what is another name for cartilage cells?
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chondrocytes
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what type of collagen is abundant in the extracellular matrix of cartilage?
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type II cartilage
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how do nutrients and oxygen get to chondrocytes?
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percolate through ground substance to chondrocytes
(cartilage is avascular) |
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what are the three types of cartilage?
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hyaline cartilage
elastic cartilage fibrocartilage |
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where is hyaline cartilage found?
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fetal skeleton
epiphyseal plates of long bones articular surfaces of bones ribcage trachea larynx bronchi |
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what is the purpose of hyaline cartilage in the fetal skeleton?
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to serve as a template for adult bone
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what is the function of hyaline cartilage in the epiphyseal plates of long bones?
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allows the bones to lengthen from birth to adulthood
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what is the function of hyaline cartilage in the articular surfaces of bones?
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acts as a low-friction cushion in movements of joints
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how are chondrocytes embedded in their extracellular matrix?
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singly or in isogenous groups of 2-8 cells from a single parent cell
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what is a lacuna?
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the space occupied by a chondrocyte
(visible only after a cell's death or shrinkage due to tissue processing) |
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what do chondrocytes do?
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synthesize and secrete extracellular proteins (e.g. type II collagen)
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what type of collagen is secreted by chondrocytes?
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type II collagen
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what organelles are prominent in chondrocytes?
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RER
Golgi complex glycogen granules |
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why are glycogen granules prominent in chondrocytes?
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chondrocytes rely on anaerobic glycolysis due to low oxygen supply
(since tissue is avascular) |
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what is the main fiber in the extracellular matrix of hyaline cartilage?
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type II collagen
(small, with refractive index approx. equal to ground substance, therefore difficult to distinguish with light microscopy) |
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what is the most prominent glycosaminoglycan in hyaline cartilage?
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chondroitin sulfate
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what composes the ground substance of hyaline cartilage?
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Glycosaminoglycans
proteoglycans hyaluronic acid glycoproteins water (60-78%) |
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what does chondronectin do?
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it is a glycoprotein which attaches matrix components and cells together
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what is territorial matrix?
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the matrix immediately surrounding a chondrocyte
(poor in collagen but rich in sulfated GAGs, so it is very basophilic and PAS-positive under light microscope) |
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what is interterritorial matrix?
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matrix further away from chondrocytes
(less basophilic and stains less with periodic acid-Schiff stain) |
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what is perichondrium?
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dense, irregular connective tissue layer surrounding hyaline cartilage, except at articular surfaces
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what is in the outer layer of perichondrium?
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fibroblasts, type I collagen, blood vessels
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what is in the inner layer of perichondrium?
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chondrogenic cells (chondroblasts)
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where is all cartilage derived from?
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mesenchyme
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when does a chondroblast become a chondrocyte?
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when it is completely surrounded by extracellular matrix
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what are the two types of cartilage growth?
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interstitial growth (within)
appositional growth (outside) |
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what do both processes of cartilage growth involve?
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mitosis
deposition of additional matrix |
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what is interstitial cartilage growth?
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new cartilage is formed within existing cartilage or mesenchyme by division of chondrocytes, giving rise to isogenous groups
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what is appositional cartilage growth?
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new cartilage is deposited along the surface of existing cartilage by differentiation of chondrogenic cells in perichondrium to chondroblasts
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what are hypertrophy and dense packing of chondrocytes associated with?
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calcification of matrix prior to bone formation
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why is regeneration of hyaline cartilage limited in the adult?
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lack of chondrogenic cells in perichondrium
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what usually replaces large tears in hyaline cartilage?
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dense connective tissue
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why does damaged hyaline cartilage show signs of calcification?
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blood vessels move into damaged area, providing higher oxygen concentration causing stem cells to differentiate into blood rather than cartilage
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what difference is there between elastic cartilage and hyaline cartilage?
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in addition to type II collagen, elastic cartilage also has a dense network of elastic fibers
(yellowish color in unstained tissue) |
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where is elastic cartilage located?
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auditory tube
epiglottis pinna of the ear small laryngeal cartilages |
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what advantage does elastic cartilage have over hyaline cartilage?
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less prone to degeneration and calcification
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what is fibrocartilage?
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combination of cartilage cells and dense, regular connective tissue
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what types of collagen are present in fibrocartilage, interspersing the chondrocytes?
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type I collagen
type II collagen |
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which types of collagen have perichondrium?
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hyaline cartilage
elastic cartilage |
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where is fibrocartilage present?
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annulus fibrosis of intervertebral discs
pubic symphysis some bone-ligament junctions |
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what makes bone unique among connective tissue, which accounts for its hardness?
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large, inorganic salt deposits in the extracellular matrix
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what is the only form of growth in bone?
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appositional growth
(no interstitial growth) |
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what function does the constant turnover of bone allow?
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bone matrix as a storage site for calcium and other minerals
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how does bone get oxygen and nutrients?
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it is highly vascularized
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what are the organic components of bone called?
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osteoid
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what are the inorganic components of bone called?
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bone mineral
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how much of bone weight do bone minerals account for?
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75%
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what minerals are bone minerals composed of?
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calcium
phosphate bicarbonate citrate magnesium potassium trace minerals |
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what is the source of calcium and phosphate in bone?
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hydroxyapatite crystals
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where are the nucleation sites for crystallization located in bone?
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on type I collagen fibers and some ground substance molecules
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what is the main component of osteoid?
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type I collagen fibers
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what are the components of osteoid?
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type I collagen
glycoproteins Vitamin K dependent proteins Proteoglycans GAGs Growth factors cytokines |
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what is the purpose of sialoproteins?
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to connect collagen fibers with cells
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what is osteocalcin? what does it do?
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a vitamin K dependent protein
captures calcium from circulation |
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what are bone morphogenic proteins?
what do they do? |
growth factors and cytokines in bone
induce the differentiation of mesenchymal cells into osteoblasts |
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what is used clinically to induce bone growth after bone surgery involving spinal fusion, graft materials, or large defects?
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recombinant human BMP7
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what is periosteum?
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the connective tissue layer covering the external surface of bone
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what are the two layers of periosteum?
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outer layer (collagenous layer)
inner layer (osteogenic layer) |
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what is the name for the type I collagen fibers in the periosteum which extend into the underlying bone matrix? what do they do?
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Sharpey's fibers
anchor the periosteum to the bone |
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what is endosteum?
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the thin, connective tissue layer cover internal surfaces of bone
(inner lining of marrow or medullary cavity and bony Haversian canals) |
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what are the four types of bone cells?
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osteoblasts
osteocytes osteoclasts osteoprogenitors |
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what are osteoprogenitor cells?
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stem cells in endosteum and periosteum capable of differentiating into osteoblasts
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what are osteoblasts derived from?
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osteoprogenitor cells
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what do osteoblasts do?
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they are the major bone-forming cells
(synthesize and secrete osteoid) |
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how do you find osteoblasts?
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they form a single layer of cuboidal, basophilic cells along bony surfaces
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what organelles are prominent in osteoblasts?
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RER
golgi apparatus |
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when do osteoblasts become osteocytes?
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when they are surrounded by bone matrix
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what are osteocytes?
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mature bone cells in lacunae in mineralized bone matrix
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what are the long, thin cellular processes of osteocytes?
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filopodia
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what do filopodia do?
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extend through narrow canals (canaliculi) in the mineralized matrix to communicate with neighboring osteocytes via gap junctions
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how do osteocytes obtain nutrients and oxygen and eliminate waste?
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through the canaliculi
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what is it called when osteocytes lyse calcium from bony matrix? when do they do this?
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osteocytic osteolysis
in response to low blood calcium |
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what is the function of osteoclasts?
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bone resorption
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what are osteoclasts?
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large multinuclear cells with acidophilic cytoplasm, with many lysosomes and mitochondria
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what are the shallow depressions called where osteoclasts reside (along bony surfaces)?
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Howship's lacunae
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what is the plasma membrane called adjacent to the bony surface?
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ruffled border
(it is highly folded) |
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what is a major enzyme released by osteoclasts into the area of the ruffled border?
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collagenase
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what is another name for bone resorption?
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osteolysis
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what breaks down the mineral portion of bone?
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HCl (from osteoclasts)
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what type of cells fuse to produce osteoclasts?
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monocyte precursor cells (CFU-GMs)
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what type of cells regulate osteoclast maturation/formation?
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osteoblasts
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what stimulates osteoclast precursor proliferation? what cells produce it?
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M-CSF
stromal cells or osteoblasts |
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what increases resorption?
what cell produces it? |
IL-1
osteoblasts |
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what hormone stimulates stromal cells to produce IL-1? what effect does this have?
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parathyroid hormone
increases osteoclast activity |
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what stimulates osteoclast differentiation?
What secretes it? |
RANKL
osteoblasts |
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what inhibits osteoclast differentiation?
what secretes it? |
osteoprotegerin (OPG)
osteoblasts |
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what are the two gross types of bone?
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spongy (cancellous)
compact (cortical) |
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what is spongy bone called when it lies between the thick plates or tables of skull flat bones?
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diploe
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where does spongy bone occur?
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epiphyses of mature long bones and short bones
between thick plates or tables of flat bones |
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what is the 3D lattice which surrounds cavities filed with bone marrow called?
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bone spicules
trabeculae |
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where are osteocytes contained?
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trabeculae
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how many layers of osteoblasts are around trabeculae?
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a single layer lines a trabeculum
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what microscopic type of bone is spongy bone?
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primary or secondary
(can be either one) |
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where is compact bone found?
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thick diaphyseal cylinder of long bones
thin covering around epiphyses tables of skull flat bone |
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how is compact bone different from spongy bone?
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lacks large spaces and trabeculae
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what microscopic type of bone is compact bone?
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ALWAYS secondary bone
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what are other names for primary bone?
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immature bone
woven bone |
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what displays an irregular or "woven" pattern in primary bone?
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Type I collagen
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what is the first bone type produced during fetal development and bone repair?
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primary bone
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what remodels and replaces primary bone?
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secondary bone
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where does primary bone persist in adults?
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tooth sockets
near skull suture lines insertion sites of tendons |
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what are other names for secondary bone?
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mature bone
lamellar bone |
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how is the collagen organized in lamellar bone?
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type I collagen fibers in each lamella are aligned in parallel and are nearly perpendicular to fibers in adjacen lamellae
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what is the name for the concentric layers of calcified matrix in lamellar bone?
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lamellae
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what are lamellae organized around?
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Haversian canals
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where are the lacunae of osteocytes located?
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between lamellae
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what is another name for a haversian system?
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osteon
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what is an osteon?
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cylindrical structure of haversian canal surrounded by lamellae in compact bone
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where are blood vessels, nerves, lymphatics, etc. of the bone?
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Haversian canals
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what structures interconnect osteons?
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Volkmann's canals
(also connect periosteum and endosteum, carrying neurovascular supply) |
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what is the name for irregularly shaped lamellae between haversion systems?
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Interstitial lamellae
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what are interstitial lamellae?
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remnants of remodeled haversion systems
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where are outer and inner circumferential lamellae?
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along the external and internal surfaces of diaphysis
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what are the two processes by which bone is formed?
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intramembranous
endochondral |
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where are bones developed from in intramembranous ossification?
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directly from mesenchymal condensations
(no cartilage present) |
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in intramembranous ossification, what is the process?
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mesenchymal cells differentiate to osteoblasts
osteoblasts secrete osteoid osteoid becomes mineralized mineralized spicules fuse forming woven bone |
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how is the periosteum formed around trabeculae in intramembranous ossification?
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formed by differentiating mesenchymal cells
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which bones are formed entirely by intramembranous ossification?
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frontal bone
parietal bones maxilla mandible (membrane bones or flat bones) |
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which bones are formed partially by intramembranous ossification?
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temporal bones
occipital bones periosteal bone collar of endochondral bones |
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how is bone formed in endochondral ossification?
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cartilage is replaced with bone
(hyaline cartilage model is precursor for bone) |
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how does endochondral ossification begin?
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mesenchyme differentiates into a hyaline cartilage model
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where is the primary center of ossification formed in endochondral ossification? how?
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along the surface of the diaphysis
vascularization transforms chondrogenic cells into osteoblasts, which become periosteum |
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how is space formed within the cartilage for the bone to grow?
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chondrocytes within diaphysis hypertrophy and degenerate, forming space
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what composes an osteogenic bud?
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blood vessels
osteoprogenitor cells |
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what does an osteogenic bud do?
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penetrates the bone collar and enters space formed by primary ossification center in endochondral ossification
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what happens to cartilage in the walls of spaces formed during endochondral ossification?
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cartilage becomes calcified
osteiod, synthesized by osteoblasts, is deposited onto calcified cartilage spicules calcified cartilage-calcified bone complex is formed |
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where do secondary centers of ossification appear in endochondral ossification?
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in the epiphyses (form epiphyseal plate)
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how do long bones grow?
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along epiphyseal plate, cartilage proliferates, and then endochondral ossification takes place
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what is it called when growth has completed (when there is no more cartilage to proliferate)?
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epiphyseal closure
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what are the zones within an epiphyseal plate?
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zone of resting cartilage
zone of proliferation zone of hypertrophy zone of calcified cartilage zone of resorption and ossification |
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what is in the zone of resting cartilage?
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typical hyaline cartilage
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what is in the zone of proliferation?
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rapid cell division, giving rise to stacks (isogenous groups) of flattened chondrocytes
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what is in the zone of hypertrophy?
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greatly enlarged chondrocytes
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what is in the zone of calcified cartilage?
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dead chondrocytes and calcified matrix
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what occurs in the zone of resorption and ossification?
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bone is deposited on calcified cartilage, then the complex is resorbed and remodeled
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what are the components of bone remodeling?
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bone resorption in some areas
bone deposition in others |
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what is the initial tissue formed at the fracture site by fibroblasts and periosteal cells? what type of tissue is it?
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collagenous tissue
aka granulation tissue connective tissue |
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in a fractured bone, what forms within granulation tissue as it becomes denser?
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cartilage
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what happens to cartilage in the granulation tissue?
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calcifies and is replaced by primary bone
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what is "primary bone tissue of the callus"?
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the primary bone which replaces cartilage in a bone fracture which is being replaced
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what are synthroses?
where are some? |
immoveable joints
connecting skull bones and joining first rib to sternum |
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what are diarthroses?
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synovial joints
joints which provide maximal movement |
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what is the outer layer of a synovial capsule composed of?
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dense connective tissue
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what is the inner layer of a synovial capsule composed of?
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synovial membrane
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what is the difference between epithelial tissue and synovial membrane?
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synovial membrane lacks a basal lamina
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what is the characterizer of osteoporosis?
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low bone mass/decrease in bone mineral density
number of trabeculae is reduced cortical bone is thinner than normal |
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what are the possible causes of osteoporosis?
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disuse of limbs
metabolic disturbances |
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what is rheumatoid arthritis?
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a clinical condition where the immune system causes inflammation in the synovial membrane
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what is the name for inflammation in the synovial membrane?
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synovitis
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what tissue is produced from the inflamed synovial membrane in rheumatoid arthritis? what does it do?
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pannus
decomposes the cartilage and underlying bone, causing severe pain and joint deformity |
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what is gout?
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metabolic disorder characterized by increased blood levels of uric acid and urate crystal deposition in soft tissues
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what is hyperuricemia?
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high uric acid in the blood
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what effect does an accumulation of urate crystals near joints cause (gout)?
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inflammatory reaction with neutrophils and macrophages
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what is a tophus or tophaceous gout?
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a subcutaneous nodule caused by the continued deposition of urate crystals in gouty arthritis
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what disorder would cause nonbirefringent monosodium urate crystals (when analyzed with polarized light microscopy) within aspirated joint fluid?
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gout/gouty arthritis
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