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Cartilage and Bone
Definitions and More
90
Physiology
Graduate
01/17/2010

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Term
what provides cells for bone growth, remodeling and repair?
Definition
endosteum and periosteum
Term
All mature bone is _____ and immature or primary bone is ______
Definition
lamellar; reticular
Term
the composition and arrangement of _____ is vital to the ability of bone to survive stress.
Definition
collagen
Term
_______ composition determines most of the properties of various cartilage types and bone
Definition
extracellular matrix
Term
hyaline cartilage function
Definition
cushion forces and a temporary skeleton (btwn joints)
Term
elastic cartilage function
Definition
flexible skeleton (ear lobe)
Term
fibrous cartilage function
Definition
anchors tendons and forms IV discs and pubic symphysis (similar to dense CT)
Term
Type II collagen is found in which types of cartilage?
Definition
hyaline and elastic as fibrils
Term
type I collagen is found in which type of cartilage?
Definition
fibrous as fibers; resemble dense CT
Term
collagen has a high ______ content
Definition
hydroxyproline
Term
what is a proteoglycan?
Definition
a core protein with GAG side chains of either chondrotin suflate or keratin sulfate that binds fluid, cations and growth factors
Term
the proteoglycans attache to ______ to form a biochemical spring and resist compression
Definition
hyaluronic acid
Term
WHat are GAG's? what kind of charge do they have?
Definition
hydrated gels that are space filling with a low mass and high volume
- negative charges that attract water
Term
what are glycoproteins? example in chondrocytes?
Definition
adhesive proteins in CT that binds cells and ECM
example - integrins - glycoprotein transmembrane receptors
Term
cartilage matrix is ______ due to the numerous negative charges from an abundance of ______.
Definition
basophilic; GAG's
- the negative charges from the cartilage binds the positive charges
Term
what are chondroblasts?
Definition
they are free cartilage cells that secrete matrix and fibers and persist in the perichondrium (around the bone) and undergo mitosis.
Term
what are chondrocytes?
Definition
cartilage cells found in lacunae surrounded by matrix; binds to collagen by chondronectin; greatest mitotic potential during growth
Term
what is chondronectin?
Definition
an adhesion molecule; a glycoprotein
Term
Interstitial cartilage growth
Definition
cells push from the inside of the ECm and occurs only in the young
Term
appositional cartilage growth
Definition
cells add to the outside of cartilage
Term
what is the original cell source for cartilage growth?
Definition
perichondrium
Term
what is the major growth promotor of cartilage>
Definition
somatomedin C (from the liver)
Term
cartilage is (avascular/vascular) and has a good/poor regenerative capacity, with a low/high metabolic rate
does regeneration exist in adult cartilage?
Definition
avascular, poor, low
- it is negligible or non-existent but the perichondrium is the cell source
Term
where is hyaline cartilage found?
Definition
articulations, temporary skeleton, ventral ends of ribs, larynx, trachea, bronchi
Term
where is elastic cartilage found?
Definition
where flexibility is required such as the auricle of the ear, the auditory tube, the external acoustic meatus, eipglottis, and parts of the larynx
Term
where is fibrous cartilage found?
Definition
IV discs, pubic symphysis, linings of tendon grooves, attachments of ligaments and tendons
Term
hyaline cartilage:
- type of collagen
- type of matrix
- basophilic/eosinophilic
Definition
collagen type II as fibrils
- homogeneous matrix
- basophilic
Term
elastic cartilage:
- type of collagen
- types of cells
Definition
- collagen type II with numerous branched elastic fibers
- numerous chondroblasts
Term
fibrous cartilage:
- type of collagen
- matrix
- how is it different than dense CT
Definition
- collagen type I
- acidophilic matrix due to collagen with + charges; little matrix with proteoglycans and few cells
- has round lacunae and stains eosinophilic not basophilic
Term
what type of cartilage is the IV disc? what are it's two main components?
Definition
- specialized fibrocartilage
- annulus fibrosis and nucleus pulposis
Term
what is the annulus fibrosis?
Definition
fibrocartilage surrounded by external layer of dense CT with type I collagen in layers at 90 degrees; ruptures occur in the posterior portion
Term
what is the nucleus pulposis?
Definition
the hyaline plate, surrounded by the annulus fibrosis; a viscous fluid that is gel-like and contains hyaluronic acid and collagen II - can be compressed
Term
which of the following pairs is not correct?
1. nucleus pulposis - fibrocartilage
2. hyaline cartilage - type II collagen
3. proteoglycans - biochemical springs
4. GAG's - bind H2O
5. hyaline cartilage - negatively charged
Definition
1. - the nucleus pulposis (hyaline plate) contains type II collagen and hyaluronic acid and is a viscous fluid
Term
a 65 year old post-menopausal female on hormone replacement therapy is diagnosed with osteoporosis. Which of the following conditions may be contributing to this condition?
- hyperthyroidism, hypoparathyroidism, excess vitamin C in diet, daily exercise, excess calcium in diet
Definition
hyperthyroidism
- normal thyroid levels are required for bone formation but excess stimulates osteoclasts
Term
which cartilage cells are mitotic?
Definition
chondroblasts; chondrocytes only during growth
Term
which bone cells are mitotic?
Definition
osteoprogenitor cells
Term
describe the cell lineage for bone cells.
Definition
1. stem cells
2. mesenchymal cells
3. osteoprogenitor cells
4. osteoblasts and osteocytes
Term
Why is bone not all solid?
Definition
to decrease body weight while giving support and structure
Term
what is compact bone (cortical)? where is it found?
Definition
contains osteons that each have a blood supply to feed the osteocytes
- found on the surfaces of bones (all external bone surfaces)
Term
what is spongy (cancellous) bone? Where is it found?
Definition
it is bone that is only 0.2 mm and is separated by marrow (soft tissue) - has a honeycomb apperance and reduces bone weight
- found on the interior of bones
Term
what is lamellar bone?
Definition
it is layered bone found in all (osteonal/compact AND trabecular) mature bone whether compact or spongy;
Term
What is the periosteum>
Definition
the outer surface of bones containing both collagen and cells
- fibrous (outer) and osteogenic (inner) layers and sharpey's fibers
Term
what are sharpey's fibers?
Definition
anchors tendons and ligaments to bone; is an attachment site; the collagen is embedded in bone to reduce tearing
Term
endosteum?
Definition
osteogenic cells line inner bone surfaces (plus small amounts of collagen)
Term
osteoblasts?
Definition
non-mitotic cells that secrete bone constituents (collagen and matrix) - not-mineralized
Term
osteocytes
Definition
non-mitotic cells in lacunae that have cell-cell contact by gap junctions and are necessary for survival
Term
what makes up bone matrix?
Definition
bone cells and minerals
Term
What does bone contain for survival (2)?
Definition
blood supply and nerves
Term
osteoid
Definition
hypomineralized matrix; organic and not mineralized; secreted by osteoblasts
Term
where are osteoclasts found?
Definition
in Howship's lacuna
Term
which type of bone requires a vascular system?
Definition
compact bone
Term
osteon
Definition
haversian system where bone is layed down inside out
Term
haversian canal
Definition
contains the blood supply, lymphatics, and nerves in osteons
Term
concentric lamellae
Definition
layers within the osteon
Term
canaliculi
Definition
canals between adjacent lacunae (osteocyte processes in canals)
Term
cement line
Definition
1-2 micrometers thick matrix with adhesion molecules and NO collagen on the outer part of the osteon
Term
Volkmann's canals
Definition
connects Haversian canals; branches of the lymph, blood, and nerves go to several Haversian canals
Term
interstitial lamellae
Definition
layers between osteons
Term
circumferential lamellae
Definition
layers at outer and inner bone surfaces
Term
what kind of bone is trabecular? what does that mean?
Definition
spongy bone
- no osteons - in bars
Term
what is the critical thickness of trabeculae?
Definition
0.2 mm
Term
what are the two types of spongy bone?
Definition
1. all immature bone
2. interiors of mature bone
Term
how do flat bones vary?
Definition
by the number of nutrient arteries
Term
how many blood supply patterns do long bones have?
Definition
2
Term
diaphysis
Definition
shaft of long bone
Term
epiphysis and metaphysis
Definition
ends of long bones
- epiphysis is the end
- metaphysis - region of bone next to the diaphyseal side of the cartilagenous plate with ossification at the edge and resorption on the interor surface
Term
is the bone matrix basic or acidic? what cells secrete it?
Definition
acidic
- osteoblasts
Term
what are the major organic components of bone matrix?
Definition
1. collagen type 1 at sites of mineralization, fibers are cross-linked to enhance stiffness
2. non-collagen proteins - include binding proteins, glycoproteins and growth factors
Term
what are the inorganic components of bone matrix?
Definition
1. hydroxyapaptite [Ca10(PO4)6(OH)2] in form of needles or plates
2. amorphous CaPO4
3. carbonate, citrate, sodium, magnesium, potassium, trace amounts of fluoride and zine; minerals are stored in bone
Term
what is teh chemical formula of hydroxyapaptite
Definition
Ca10(PO4)6(OH)2]
Term
hydroxyapatite crystals -
1. form
2. where are the zones of crystals?
3. hydration shell?
Definition
1. needles
2. interior surface
3. facilitates ion exchange between hydroxyapatite and body fluids
Term
what percentage of bone weight is mineral? percent of volume?
Definition
weight = 75%
volume = 50%
Term
what are the nucleation sites?
Definition
collagen and secreted vesicles
Term
what are osteoclasts?
Definition
derived from monocytes and are multinucleated due to the fusion of several monocytes; cause resorption
Term
what are the 2 resorption mechanisms of monocytes?
Definition
1. hydrolytic enzymes - remove organic matter
2. secetion of H+ for high acidity - demineralization
Term
osteopetrosis
Definition
dense bone due to a genetic disease - osteoclasts lack ruffled borders and do not resorb enough bone - heavy dense bone develops due to poor osteoclast function
Term
Wolff's Law
Definition
internal architecture changes reflect bone function and reflect alterations in weight-bearing stresses and forces exerted by muscles
Term
what are some things that lead to bone loss?
Definition
1. prolonged bed rest
2. immobilization
Term
osteoporosis
Definition
decreased bone density - most common skeletal disorder in the world due to an imbalance in bone resorption and bone deposition
Term
what are the major sites of osteoporosis? what are teh most common forms?
Definition
- vertebrae, femoral necks and wrists
- postmenopausal and age-related - estrogens decrease bone resorption
- other causes include diet deficiencies, endocrine, drug-induced
Term
What 4 hormones increase bone matrix and how?
Definition
1. calcitonin - inhibits osteoclast resorption
2. estrogens - decrease rate of bone turnover
3. androgens - increase bone density
4. growth hormone - increases bone deposition
Term
what are 2 hormones that decrease bone matrix and how?
Definition
1. parathyroid hormone - calcium shift from matrix to extracellular fluid (hypercalcemia)
2. excess thyroxine - stimulates osteoclast resorption
Term
Bone v. cartilage:
1. osteogenic cells become....
2. which divide? (osteoblasts and osteocytes/chondroblasts and chondrocytes)
3. which is vascular
4. which is mineralized and which has high proteoglycans
Definition
1. osteoblasts (bone) and chondroblasts (cartilage)
2. chondroblasts and chondrocytes in cartilage
3. mature bone
4. bone is mineralized with less chondroitin sulfates than in cartilage, low proteoglycans with low water; cartilage can become mineralized and is high in proteoglycans with high water
Term
bone v. cartilage
1. which had dense collagen and which kinds
2. which has a low (Ca)(P) ratio
3. bone has ___% collagen as dry weight and cartilage has ___ %
4. growth is ____ in bone and ___ in cartilage
5. in bone ____ secretes alkaline phosphatase and in cartilage ____ secretes it
Definition
1. bone has dense collagen type I and cartilage has less collagen and type II
2. cartilage
3. 90% in bone and 40% in cartilage
4. bone = appositional
cartilage = appositional and interstitial
5. osteoblasts in bone
chondrocytes in cartilage
Term
what is the epiphyseal plate or growth plate?
Definition
plate of cartilage that separates the diaphysis and epiphysis duiring bone growht; has zones of inactivity, proliferation, hypertrophy, calcification
Term
describe immature bone
Definition
- more cells than mateure
- more heterogeneous ECM
- always non-lamellar
- disorganized collagen
Term
describe mature bone
Definition
always lamellar
- collagen in a lamella is in the same plane but adjacent lamella are in a different one
Term
what is the primary center of ossification in the long bone?
Definition
diaphysis
Term
major cartilage properties are due to which 2 things?
Definition
proteoglycans and GAG's
Term
bone strength is due to _____ and hardness is due to ____
Definition
collagen, hydroxyapatite
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