Bone and Cartilage Flashcards
Cartilage Tissue function and characteristics
function: support with the ability to withstand mechanical stress without permanent distortion.
- avascular;
- lacks nerves and lymphatics
- poor healing
How does Cartilage tissue get its nourishment?
diffusion from capillaries and tissue fluid.
What is the function of Bone
Protection, support, blood formation and attachment site for skeletal muscle
What is the difference between perichondrium and periosteum?
Both are vascular and innervated, contain fibroblasts, collagen and ground substance
Periosteum covers the external surface of bone. contains osteogenic cells
Perichondrium: covering all cartilage except articular cartilage and fibrocartilage. contain chondrogenic cells. fibroblasts are rich in type 1 collagen
chondroblast
sphindle shaped
-synthesize and deposit cartliage
Function of chondrocyte
-completely surrounded by extracellular matrix- -can produce extracellualr matrix and metalloproteinase
Metalloproteinase
An enzyme that degrades cartilage material , allowing cells to reposition themselves
Isogenous groups and what do the contribute to
groups of 2-5 chondrocytes that were derived from a single progenitor cell
- contribute to interstitial growth
Lacunae
cavities in the matrix that contain individual chondrocytes
Pericellular matrix and how does it stain
(capsule)
-located immediately around the chondrocytes, dark basophilic stain
Differentiate between territorial and interterritorial matrix.
Interterritorial matrix is poorly stained; more acidophilic, more collagen fibers than terriorial matrix. between isogenous groups
Territorial matrix stains basophilic
- surround isogenous group
- more ground substance than capsule
- metachromatic-chondroitin sulfate
Cartilage canals
> 3mm, may have blood vessels carrying blood somewhere else
Two forms of cartilage growth: Appositional and Interstitial. Identify the similarities and differences.
Appositional growth (at surface): proliferation of chondrogenic cells into chondroblasts
Interstitial growth (within: cell division of preexisting chondrocytes within cartilage. Occurs during early phases of cartilage formation, increase tissue mass by expanding cartilage within.
Similarities: synthesis of matrix contributes to cartilage growth
Developing cartilage
proliferation within
-rationale for isogenous groups
Mature cartilage
made of isogenous groups- (2-5) cells per group (chondrocytes)
What determines different cartilage types?
composition of the matrix
Interstitial material of all cartilage
-very hydrated (60-80%) by weight
-collagenous fibers (type 2 collagen)
-elastic fibers
-ground substance :
chondroitin, keratan sulfate, hyaluronic acid
In H and E stain. What color does chondroitin stain? What color does collagen basic protein stain?
basophilic, acidophillic
What is fibrocartilage characterized by?
A few chondrocytes arranged in columns or rows- acts as transition tissue between hyaline cartilage, bone and fibrous tissue.
Endosteum
covers inner of bone- represents boundary between bone matrix and marrow cavities
Lacuna
Space in bone matrix around an osteocyte
Cannaliculi
connect lacuna to lacuna, will have capillaries and nerve fibers will send out projections that communicate with other osteocytes
Sharpey’s fibers
collagen fibers from periosteum, continous with collagen fibers of bone-found at bone/tendon or ligament junction. insert oblique or perpendicular to the access of the bone. Insertions are very strong.
What are the differences in structure of hyaline, elastic and fibrocartilage?
Hyaline: Type 2 collagen,transparent in thin sections
Elastic: matrix fibers are collagenous and elastic. type 2 collagen
fibrocartilage: LACKs Perichondrium, so growth depends on interstitial growth. characterized by few chondrocytes arranged in columns and rows
What is does each type of cartilage function?
hyaline: forms embryonic skeleton and provides longitudinal growth of bone.
elastic: flexible support
fibrocartilage: acts as a transition tissue between hyaline cartlage, bone and fibrous tissue. function: firm support with tensile strength.
Differentiated and specialized for supporting weight- dynamic tissue continuously being reorganized- highly vascular contrary to cartilage refers to what type of tissue
osseous
Intercellular matrix that is calcified material is what type of matrix and is it vascular?
Bone matrix
-avascular
osteroblast
- immature, synthetically active;
- produces osteoid
- release alkaline phosphatase.
osteoid (24% bone matrix)
extracellular nonmineralized material.
- Non-calcified matrix of organic compound.
- type 1 collagen
- proteoglycans and glycoproteins
- y-carboxyglutamate containing phosphoproteins
osteocyte
mature, synthetically inactive.
- stellate body
- cytoplasmic processes that allow for nutrient transfer from cell to cell and gap junctions
- canaliculi
- lacuna
Lacuna
space in bone matrix around osteocyte
metabolits can’t get through calcified bone, so what does bone rely on to get its nutrients. what does this structure contain.
Canaliculi: connect lacuna to lacuna, will have capillaries and nerve fibers. osteocytes will send out projections that communicate with other osteocytes
osteoclast
multinucleated, large, ruffled border (to increase surface area)
- cytoplasmic processes an microvilli.
- use ameboid movement
- secrete lysosomes
- derived from monocye
- degrade bone
what doe alkaline phosphotase do?
ossifies osteoid, immature bone and cartilage.
What relationship does parathyroid hormone and calcitonin in osteoclast activity in bone reabsorption. State which one is direct and indirect.
Parathyroid Hormone: indirectly increase osteoclast activity and increase bone reabsorption. (no receptor for PTH)
Calcitonin: directly inhibits osteoclast activity and reduces bone reabsorption.
osteoclast activity creates what figure?
Howship Lacunae: area of bone resorption.
What is inorganinc (calcified) matrix composed of? 76%
forms calcium phosphate crystals composed of needles.
-hydroxyapatite
ossification (mineralization of organic matrix) occurs where?
nucleation sites along collagen (NOT CELL NUCLEUS)
osteoblasts secrete what 2 molecules that stimulate osteoclast formation
(M-CSF and RANKL)
osteoclasts are more active than osteoblasts with age- results in what
loss of bone mass in postmenopausal women because loss of estrodiol, osteoclast activity accelerates
E2 replacement inhibits
osteoblasts’ synthesis of interleukin 6 (cytokine that stimulates development of osteoclasts. leading to osteoporosis)
Endosteum size, function and what is it made of?
- one cell layer thick, thinner than periosteum
- made of active and inactive osteoblasts
- lines spicules and internal cavities in bone.
trabeculae of cancellous bone is found where?
in inner core of bones (mostly at epiphyses of long bone, flat bone, inner and outer tables of skull
haversian canal contains
blood vessels, capillaries, venules, arterioles and nerves.
lamellar matrix
alternates orientation- strengthen bone
Deficiencies in Vitamin C would result in what for cartilage and bone?
Cartilage: decrease in growth due to inadequate collagen synthesis.
Bone: scurvy-inability to produce bone matrix.
Deficiencies in Vitamin D would result in what for cartilage and bone?
Cartilage: abnormal growth because Vit D is needed for calcium absorption
Bone:bone deforms easily due to poor calcium absorption; leads to rickets in children. osteomalcia in adult.
Deficiency in calcium or phosphorous in bone leads to
rarefaction of bone, making it more porous, less dense; result more subject to fractures
Deficiency in protein and mineral deficiencies results in what for cartilage
decrease in growth
what type of radiation isotopes replace calcium in bone, in addition to bone degeneration,, mutation of bone marrow and may be induced and can result in leukemia
calcium 45, phosphorous 32, lead 210
What is required for normal growth of cartilage
growth hormone and thyroxine
What is the role on parathyroid hormone and calcitonin on calcium levels?
PTH: elevates blood calcium levels-mobilizes the release of calcium from bone
Calcitonin:suppresses mobilization of calcium from bone matrix-lowers blood calcium levels
The main difference between intramembranous ossification and endochondral ossification is.
Intramembranous does not use cartilage template; bone formation involves the transformation of condensed mesenchymal tissue
What type of bones are developed by intramembraneous ossification and which use endochondral ossification?
IO: flat bones of skull, face, mandible, clavicle
EO: bones of extremites and weight bearing
differentiate between nonlamellar and lamellar bone.
lamellar bone: mature, has haversian systems
immature bone: bundle or woven bone.
- more cells/ units area
- cells in random orientation
- more basophilic (high ground substance) than mature bone.
- grow more rapidly
Give examples of where immature bone can be found.
in adult alveolar socket, tendon insertions, and areas of remodeling
What is the process for intramembraneous direct ossification?
- Occurs through activity of periosteal membrane tissue.
- condensation of mesenchymals cells of mesenchymal cells where bone is destined to be formed
- mesenchymal differentiate into osteoprogenitor cells
- Increased VASCULARIZATION occurs
- osteoprogenitor differentiate into osteoblasts
- osteoblasts secrete osteoid
- osteiod thicken spicules after mineralization “woven bone”
- cells become more separated by remain attached to cytplasmic processes.
- woven bone eventually turns into lamellar bone
Summarize primary ossification center of Endochondral (indirect) ossification in hyaline cartilage.
- mesenchymal cells proliferate, aggreagate, then differentiate into cartilage chondroblasts to produce matrix. PERICHONDRIUM FORMS
- Vascularization of perichondrium cause chondrogenic cells to transform into osteoprogenitor cells. PERICHONDRIUM becomes PERIOSTEUM. OPC become osteoblasts
- Periosteal bone collar forms
4**. chondrocytes undergo HYPERTROPHY and degenerate. lacunae become confluent, forming large cavities. HC alkaline PHosphatase stimulate calcified cartilage. - osteoclasts create perforations in bone collar that permit the periosteal bud
- osteoblasts secrete osteoid that become calcified, forming mixed spicules.
- periosteal bone collar thickens and elongated toward epiphysis
- osteoclasts begin to resorb
- repetition of this sequence
Summarize 2nd ossification center of Endochondral (indirect) ossification in hyaline cartilage.
develops similarly to primary center except a BONE COLLAR IS NOT FORMED.
-episphyseal plates continue to grow by adding new cartilage until the 2 ossification meets.
Growth in diameter is due to:
- periosteum that contains osteoblasts
2. osteclasts
what are the 3 types on ground substance?
chondroitin (6-sulfate and 4-sulfate), keratan (resists compression) sulfate, hyaluronic acid
Herniation of an intervertebral disk. common cause.
pain in lower back and neck
-risk factor include age, occupation, lifestyle and genetic
Degeneration of IV disk is due to what factors?
changes in hydration of nucleus pulposus and strength of collagen, leading to weakening of annulus fibrosus (fibrocartilage).
-degenerated disk nucleus pulposus loses its cushioning ability and exerts uneven pressure on the surrounding annulus. extrusion of nucleus pulposus through weakened annulus (herniation)
Degeneration of IV disk: In L4 to L5 and L5 to S1 causes
back pain and neurologic symptoms because of compression of nerve roots.
In H and E, calcified cartilage and bone stains what color
Calcified cartilage: basophilic
bone: acidophilic
