Usmle Cartilage And Bone Histology

Front 1

cartilage

Back 1

specialized connective tissue rich in collagen II, and GAGs, is avascular

Front 2

what is the major cell type of collagen and what is its differentiation cascade?

Back 2

messenchymal stem cells in perichondrium --> chondroid precursor cell --> chondroblast --> chondrocyte

Front 3

two manners of cartilage enlargement?

Back 3

appositional growth = new cells, increases width
internal/interstitial growth = hypertrophy and increased ECM = increased length

Front 4

differentiate between new and old cartilage by staining, and what is the reason for this difference?

Back 4

New cartilage is produced by mainly chondroblasts which secrete more collagen II > GAGs this will stain Pink as cartilage ages the c-blasts become c-cytes which secrete GAG>Collagen II so they will stain more blue

Front 5

hyaline cartilage

Back 5

this type of cartilage is the template for bone formation and is the articular cartilage of joints. Lots of GAGs, high water content, resists compression

Front 6

elastic cartilage

Back 6

stretchy, lots of elastin, ears, and throat, lots of collagen II

Front 7

fibro cartilage

Back 7

highest tensile strength, lots of collagen I and some II, ligament attachments and intervertebral disks, has no perichondrium little water retention

Front 8

what are the two forms of bone?

Back 8

compact bone and spongy/cancellous bone where hematopoiesis takes place

Front 9

what is the stem cell and differentiation cascade of the primary bone marrow cell?

Back 9

messenchymal stem cell --> osteoprogenitor --> osteoblast --> osteocytes

Front 10

what special connective tissue component to osteoblasts secrete?

Back 10

osteoid, type I collagen, GAGs

Front 11

in what direction to osteoblasts secrete bone?

Back 11

in a polarized manner causing appositional growth

Front 12

what is bone made of?

Back 12

bone is calcified osteoid which conssists of the the osteoid and hydroxyapetite crystals formed by Ph and Ca deposition

Front 13

what is unique about osteocyte survival and communication?

Back 13

they communicate via gap junctions and long communication extensions through the bone canalliculi, these processes are bathed in EC fluid

Front 14

what role do oteoblasts play in monocyte differentiation?

Back 14

they secrete M-CSF causing monocytes to differentiation to macrophages

Front 15

how do macrophages differentiate into osteoclasts?

Back 15

interaction with osteoblast RANK-L

Front 16

which factors are involved in osteoclast activity regulation?

Back 16

calcitonin and vitamin D3.

Front 17

what is a howships lacuna?

Back 17

the space carved out by osteoclasts degrading calcified bone

Front 18

what is unique about intramembranous bone formation?

Back 18

primitive messenchyme can differentiate directly to bone, without requiring a cartilagenous scaffolding.

Front 19

where does intramembranous bone formation occur

Back 19

flat bones, skull, embryogenesis, to form primary spongy bone

Front 20

what are the steps of bone growth?

Back 20

primary spongy bone becomes dense cortical bone, lacking intramembranous spaces and messenchyme, this remodels to lamellar bone and the exterior surface of bones

Front 21

how does the marrow cavity form?

Back 21

the central primary spongy bone trabeculae widen to form cancellous bone

Front 22

what is endochondral bone formaiton

Back 22

forms on hyaline cartilage, occurs in long bone extemeties, vertebrae, pelvis, requires chondroblasts and chondrocyte differentiation

Front 23

differentiate the role of endochondral ossification and intramembranous ossification in long bone growth

Back 23

endochrondral begins in the center at the diaphysis and expands outward, replacing the central/inner cartilage with bone and increases length.
at the bone surface from the periosteum intramembranous ossification occurs forming the bone cortex.

Front 24

how does bone formation occur, in what direction?

Back 24

central cartilage grows and expands, with primary ossification chasing behind it, and everything chases the epiphyseal growth plate, which closes at puberty

Front 25

what is the reserve zone

Back 25

chondrocytes in epipheseal growth plate

Front 26

proliferating zone

Back 26

deep to reserve zone, contains proliferating chondrocytes,

Front 27

zone of hypertrophy

Back 27

deep to prolif zone, hypertrophic growth, lots of collagen production, chondrocytes in this zone are undergoing apoptosis

Front 28

how does perichondrium differentiate to periosteum

Back 28

growth factors induce stem cells to differentiate into osteoprogenitor cells, and osteoclasts attack the cartilage matrix

Front 29

differentiate between haversion canals and spicules?

Back 29

spicules are perpendicular to bone axis, haversion canals are along bone axis.

Front 30

ddx between volkmans canals and haversion canals

Back 30

volksmans canals are perpendicular to haversion canals and lack a surrounding osteon

Front 31

what is an osteon

Back 31

this is the basic unit of mature/cortical/lamellar bone, it is a canal bore out by osteoclasts, new osteblasts move in and deposit osteoid, this forms a canal surround by lamellae