Histology Block Two First Exam

Front 1

cartilage

Back 1

solid form of connective tissue with varying degrees of solidity ranging form the firmness of a rubber eraser to that of a silicon gel

Front 2

general characteristics of cartilage

Back 2

-chondrocytes: in lacunae, contain lipid droplet/vacuole
-avascular: O through matrix of chondrocytes. vulnerable to degeneration, becomes opaque and yellowish with age
-perichondrium: layer of dense connectve tissue surrounding cartilage
-

Front 3

types of cartilage growth

Back 3

-appositional: formation of new cartilage at surface just beneath perichondrium
-interstitial: internal formation of new cartilage via re-conversion of lacunae bound chondrocytes to chondroblasts: impeded by avascular nature

Front 4

types of cartilage

Back 4

dffer according to fiber content
-hyaline, fibrocartilage, elastic

Front 5

hyaline cartilage

Back 5

hardest and most abundant
-matrix has few/fine collagen fibers only visible with e microscopy
-found in : articular cartilages, tracheal rings, costal cartilages, thyroid cartilage and nose

Front 6

fibrocartilage

Back 6

more pliable: contains a lot more collagen fibers in matrix that are visibl with light microscopy
-locations provide tough support with tensile strength

Front 7

elastic cartilage

Back 7

most pliable
-interlacing elastic fibers
-external ear, epiglottis, larynx

Front 8

general structural components of bone

Back 8

-cortex (compact bone): deposited in layers called lamellae
-spongy or cancellous bone (found in epiphyses and peripheral to medullary cavity)
-

Front 9

spongy or cancellous bone

Back 9

-contains blood cell progenitors and adipose
-crossed by bony spicules called trabeculae (contain spaces for marrow and other connective tissues)

Front 10

compact bone

Back 10

deposited as woven bone
-lamellae concentrically arranged around haversion canal that transits nerves and blood vessels
-lamellae delineated by lacunae: contain osteocytes
-lacunae connected by fine canaliculi: have ytoplasmic extensions that nutritionally inter-connect osteocytes to vessels of haversion canal
-interstitial lamellae: components of previous haversino systems that are no longer obvious due to remodeling
-Volkman's canals: transversely connect Haversion canals

Front 11

components of bone

Back 11

cells
matrix

Front 12

bone cells

Back 12

only seen in decalcified preps
osteoprogenitor cells
osteoblasts
osteocytes
osteoclasts

Front 13

osteoprogenitor cells

Back 13

undifferentiated fibroblast-like cells that give rise to osetoblasts: few that persist in adult bone are located deep to periosteum

Front 14

osteoblatss

Back 14

synthesize glycoproteins and mucopolysaccharides that are secreted to form uncalcified ground substance called osteoid

Front 15

osteocytes

Back 15

formed when osteoblasts become surrounded by matrix and therefore encased within a lacunae

Front 16

osteoclasts

Back 16

large multinucleated cells that digest bone matrix
-typically found in Howship's lacunae: indentations in compact bone due to osteoclast reabsorption

Front 17

matrix

Back 17

strength from highly ordered collagen fibers (osteoid-primarily collagen fibers)
-rigidity from minerals: primarily calcium hydroxyapatite

Front 18

lining of bone

Back 18

contains both internal (endosteum) and external (periosteum) lining of simple squamous epithelia plus underlying dense irregular connective tissue
-sharpeys fibers: attach bone to periosteum

Front 19

intramembranous ossification

Back 19

results in the formation of flat bones
-directly from mesenchyme to bone. Mesenchyme becomes highly vascularized:rapid cell proliferation
-differentiation of some cells in to osteoprogenitor cells and osteoblasts: produce osteoid within connective tissue
-lamellar bone replaces osteoid

Front 20

endochondrial ossification

Back 20

hyaline cartilage model is replaced by bone from within: cartilage remailes at joint surfaces
1. proliferation and hypertrophication of cartilage cells: lacunae increase in number/size
2. calcified by lime salts
3. cells below perichndrium differentiate in to osteoprogenitor cells- osteoblasts- deposit bony thing collar
4. periosteal buds: vascular tissue from periosteum invades through collar and infiltrates enlarged lacunae- marrow spaces
5. replacement of lime salts with calcium hydroxyapatites

Front 21

where does endochondrial ossification occur

Back 21

at primary ossificatino center in diaphysis and at secondary ossification centers in each epiphysis
short bones: only have primary

Front 22

growth of flat bones

Back 22

increased size without increased thickness of compact bone
-osteoblasts deposit new bone along external surfaces
-osteoclasts reabsorb along internal surfaces

Front 23

growth of long bone

Back 23

-appositional growth: increased diameter via intramembranous ossification on xternal surface of collar with osteoclast activity on internal surface
-longitudinal growth: viewed as sequential zones in growh plate

Front 24

different zones in longitudinal growth

Back 24

1. zone of reserve cartilage
2. zone of cell proliferation
3. zone of cartilage calcification: zone of variable length but always narrow
4. zone of provisional ossification

Front 25

sequence of hemopoietic organs and blood cell types

Back 25

1. yolk sac: first site of hemopoiesis with production of megaloblasts
2. liver followed by spleen with production of macrocytes
3. bone marrow: production of erythrocytes

Front 26

hemoglobin in adult vs. embryonic

Back 26

adult: two alpha, two beta
made in bone marrow
embyronic: four e
made in yolk sac
fetal: two alpha, two y
made by liver an spleen
RBC's containing hemoglobin F quickly destroyed by liver after birth and replaced by RBCs with adult hemoglobin

Front 27

development of cartilage

Back 27

1. overlying epithelia induces conversion of mesenchymal cells in to pre-chondrogenic cells
2. condensation: mitotic division diviion of pre-hondrogenic cells creates a clumping of cells
3. differentiation: pre-chondrogenic cells differentiate into chondroblasts that begin laying down cartilage matrix

Front 28

different types of bones and how they develop

Back 28

long bones: result from endochondrial ossification with primary and secondary ossification centers
short bones: endochondrial ossification with only primary oss center (knee cap)
flat bones: intramembranous ossification (cranium, sternum)
irregular bones: combo of short and flat bones (vertebrae)

Front 29

development of vertebra

Back 29

1. sclerotome cells migrate to surround neural tube and notochord
2. week 5: vertebrae composed of mesenchyme w/ notochord in center of body
3. week 6: chondrification of vertebrae begins at chondrification centers
4. week 7: primary ossification soon followed by itnramembranous ossification
5. vertebrae at birth still has cartilage at dorsal tip of vertebral arch not replaced until age 3-5
6. secondary ossification centers occur at puberty

Front 30

fate of notochord

Back 30

1. replaced by bone within body of vertebrae
2. between vertebrae: surrounded by fibrous tissue to become the nucleus pulposus (only remnant left in a healthy individual)

Front 31

chordoma

Back 31

highly invasive slow growing tumor resulting from persistent remnant of notochord: high rate of mortality because hard to target due to slow growth

Front 32

development of skull

Back 32

1. cartilagenous neurocranium: forms base of skull
2. membranous neurocranium: forms calvaria
-bones held together by fibrous joints called sutures
-fontanels: large fibrous regions where sutures meet
3. cartilaginous viscerocranium: forms bones of middle ear plus hyoid bone
4. membranous viscerocranium: primarily forms bones of mouth