Oral H & E 2 exam 1

bone is highly vascularized, dental materials avascular

key difference between bone and dental hydroxyapatite materials (enamel, dentin, cementum)

osteocyte

a bone cell embedded within the bone matrix, responsible for maintaining bone tissue

60% inorganic, 40% organic

composition of bone

sialoprotein

major protein in bone that plays a crucial role in mineralization and structural integrity.

type I

type of collagen found in bone

bone remodeling

process by which new bone is deposited and old bone is resorbed

support, protection, levers, reservoir (calcium/phosphate), blood cell production

functions of bone

compact (cortical) bone

high density of bone material tightly packed, filled wil OSTEONS and HAVERSIAN canals

spongy/cancellous/trabecular bone

lighter, less dense bone with a porous structure with low density of material to volume

lamellae

thin layers of bone matrix that form around Haversian canals in compact bone.

woven bone

first bone deposited, forms rapidly, poorly organizes and LESS mineralized

concentric lamellae

Identify A

circumferential lamellae

Identify C

interstitial lamellae

identify B

periosteum

fibrous outer layer of dense connective tissue that surrounds bones, point of attachment for tendons and ligaments

sharpey’s fibers

thick collagenous fibers that connect the periosteum to the underlying bone.

inner

which layer of the periosteum is CELL RICH

endosteum

internal lining of central cavity of bone and trabeculae

reticular fiber CT

what type of connective tissue is the endosteum

outer dense CT periosteum

layer of periosteum connected to surface of bone by SHARPEY’S FIBERS

osteoprogenitor,osteoblasts, stem-like periosteal, fibroblasts

cells found within cell rich inner periosteum

osteoblasts

Bone-forming cells responsible for synthesizing and mineralizing the bone matrix.

osteoid

the unmineralized, organic portion of the bone matrix secreted by osteoblasts that REGULATE CALCIUM and PHOSPHATE

bone lining cells

osteoblast that flatten and line the surface of bones; regulate passage of minerals and assist in maintenance

alkaline phosphatase (AlPase)

enzyme secreted by OSTEOBLAST that cleave phosphate for HYDROXYAPATITE FORMATION

where cells are NOT secreting

where can alkaline phosphatase be found

sialoprotein, osteopontin, osteosialoprotein

mineralization promoters (loci) that regulate CaPO4

osteocytes

osteoblasts that have been trapped in mineralized matrix

rate of bone formation

what affects the conversion rate of osteoblast to osteocyte

osteocytic lacunae

small cavities in bone housing osteocytes.

canaliculi

Enclosed channels around osteocyte processes that connect osteocytic lacunae

canaliculi

what allows for osteocyte regulation of bone repair, formation, and removal

gap junctions

how do osteocyte contact adjacent cell processes

sclerostin

marker of mature osteocyte, NEGATIVE REGULATOR of bone FORMATION

osteoclasts

multinucleated cells responsible for bone RESORPTION and remodeling.

monocytes

what cells do osteoclast arise from

osteoblasts

what cells must be present for osteoclast formation

RANKL

a protein necessary for osteoCLAST differentiation and activation

IL-1a

stimulates osteoCLASTS to RESORB bone

hormones

what mediates osteoclast driven bone resorption

cathepsin

COLLAGENASE involved in the degradation of the bone matrix and activation of osteoclasts.

MMP9

gelatinase and recruiter of osteoclasts

activation, resorption, formation

phases of bone remodeling

cutting cone

structure of osteoclasts and osteoblasts, that facilitates the removal of old bone and the deposition of new bone.

type H cells (HECs)

cells that induce formation of new blood vessels in bone

noggin

secreted by HECs, sustains osteoblasts

VEGF

molecule secreted by OSTEOBLASTS that supports angiogenesis

stimulates OPCs to release SCF leading to increased immune response

how does exercise affect bone

SCF (stem cell factor)

stimulates common lymphoid progenitors (CLPs) to differentiate into various types of blood cells.

bone modeling

process of establishing bone size and shape

cartilage growth/endochondral ossification and intramembranous ossification

modes of ossification

endochondral ossification

ossification in which osteoblasts produce osteid on pre-existing hyaline cartilage

long bones

where does ENDOCHONDRAL ossification occur

intramembranous ossification

bone formation in which osteoblasts differentiate directly from mesenchyme and secrete osteoid

flat bones (skull, jaw, clavicle, bone repair)

where does intramembranous ossification occur

woven

what kind of bone is formed from endochondral and intramembranous ossification

ossification

process of new bone formation on organic matrix

proliferation (1), hypertrophy/maturation(2), mineralization (3)

zones in endochondral bone formation

chondroblasts

cells that produce cartilage matrix, key in formation of cartilage during endochondral ossification.

osteoblast produce new bone in spicules radiating from ossification center

how does intramembranous ossification occur

intramembranous ossification

what process is occur in this picture

endochondral ossification

what process is occuring in this picture

osseous drift

process where bone tissue is reshaped due to mechanical stress and growth.

scurvy

vitamin C deficiency that impairs collagen and osteoid secretion

rickets

calcium/phosphate or Vitamin D deficiency in children that leads to improper bone mineralization and bone deformities

osteomalacia

phosphate/vitamin D deficiency in adults that leads to decrease mineral content of bone

osteoporosis

bone resorption is greater than bone deposition

osteopenia

lower mineral density/ pre osteoporosis

osteopetrosis

impaired osteoclast function leading to more mineralized brittle bone

bisphosphonates

a class of drugs that inhibit bone resorption by preventing osteoclast activity, commonly used to treat osteoporosis.

osteoclast ruffled border

site of secretion of acid and protenases

BRONJ

a serious condition characterized by the presence of exposed bone in the maxillofacial region, associated with bisphosphonate therapy.

W9

inhibits osteoclast differentiation via blocking RANKL signaling

stimulate osteogenesis and formation of osteoblasts

what is the effect of W9

mesenchymal stem cells

what are OSTEOBLASTS derived from

paraxial mesoderm

forms POSTERIOR parts of vault and cranial base

paraxial mesoderm and neural crest

what is the developmental origin of cells that form the cranioskeleton

mesenchyme

what type of cells do neural crest cells and paraxial mesoderm cells develop into

both neural crest and paraxial mesoderm

mesenchymal cells from what origin form cartilage, bone, and tendon

interstitial, fast growth, no remodeling

features of growth in cartilage

appositional, continuous remodeling

growth features of bone

hormone

what is the regulation mechanism of cartilage

mechanical

what is the regulation mechanism of bone

cartilage

tolerant of compression, higher compressive load slows elongation

bone

grows in direction of tension, resorbed under direct compression

fibroblasts, chondroblasts, or osteoblasts

cells that originate from mesenchyme cells

chondrocranium

forms cranial base

sensory capsules, body of sphenoid, occipital bone

centers of chondrification of chondrocranium

chondrocranium, pharyngeal skeleton/arch, secondary cartilages (coronoid, symphyseal, condylar)

what bones are preformed in cartilage

middle ear, base of great wing (sphenoid), lingula, styloid, hyoid

parts of pharyngeal skeleton

coronoid, symphyseal, and condylar

secondary cartilages

spheno-occipital synchondrosis, nasal septum, mandibular condyle

sites where cartilage persists throughout growth period, important for postnatal growth

controls on growth are different and affects growth potential

why is important to know how bones ossify

secondary cartilages

what contributes of growth of the mandibular symphysis (symphyseal)

intramembranous

type of ossification of desmocranium

facial bones

ossifications of facial dermis

apposition and resorption (NO INTERSTITIAL)

method of growth of bone

functional matrix hypothesis

the idea that soft tissue growth, spaces, and muscle contraction influence the growth of bone and skeletal structures.

surrounding tissues and mechanical loading

what controls bone growth

growth at spheno-occipital synchondrosis

leads to elongation of skull (A-P) and dispaces frontal bones and viscerocranium forward