MCM Final - Structural Connective Tissue

Question 0

hyaline

Answer 0

cartilage type - articular surfaces, etc.

• most common
• clear cartilage that can resist compression
• matrix has collage type II fibers

Question 1

Cartilage

Answer 1

rigid, flexible, and resilient

three types:
hyaline, elastic, and fibrous

cells - chondrogenic, chondroblasts, chondrocytes

fibers - collagen and elastic

ground substance - aggrecan (GAG) and chondronectin (adhesive glycoprotein

Question 2

elastic cartilage

Answer 2

contain collagen type II

pinna and epiglottis
high concentration of elastic fibers

Question 3

fibrous cartilage

Answer 3

aka fibrocartilage

pubis symphysis, intervertebral disks

has collagen type I

Question 4

What cell type does cartilage develop from?

Answer 4

embryological mesenchyme

Question 5

chondroblasts

Answer 5

cells in cartilage that will produce new cells

Question 6

chondroblasts

Answer 6

cells in cartilage that are actively proliferating

Question 7

chondrocytes

Answer 7

cells in cartilage that are not proliferating

Question 8

lacunae in cartilage

Answer 8

chondroblasts become chondrocytes grouped together surrounded by matrix

-group of chondrocyte cells separated from matrix is lacunae

Question 9

perichondrium

Answer 9

layer of irregular connective tissue around cartilage

• two layers:
  
  • fibrous - outer layer
  • cellular - inner layer

source of all future chondroblasts and chondrocytes

Question 10

Cartilage Growth

-two types?

Answer 10

appositional - at the surface
-adds new cartilage at the periphery

interstitial - expansion of matrix from within

Question 11

regulation of cartilage growth

Answer 11

growth hormone - stimulatory (insulin-like growth factor 1)
thyroid hormone - stimulatory (directly and IGF-1)
-stimulates hypertrophy
glucocorticoid - inhibitory
-down-regulate collagen type I
-up-regulate collagenase type III
testosterone - stimulate
estradiol - inhibitory
vitamin A deficiency - slows growth and calcification
vitamin C deficiency - inhibits collagen synthesis (scurvy)
vitamin D deficiency - inhibits calcification

Question 12

Scurvy

Answer 12

result of vitamin C deficiency

-inhibits collagen synthesis

Question 13

Wolff’s Law

Answer 13

bone adapt to the stress place on it

-change in bony structure

Question 14

Bone composition

Answer 14

40% organic - collagen I (arranged radially each lamellar ring)
-polysaccharides, aggrecans, chondroitin-4,6 sulfate, heparan sulfate

60% inorganic - hydroxyapatite salt (calcium salt)
-plates that align with collagen fibers

Question 15

lamellae

Answer 15

calcified interstital rings in bone

surround Haversian canal and are interspersed with lacunae

collagen in every other lamellae is perpendicular (extra strength)

Question 16

lacunae

Answer 16

small cavities within each lamellae

contain osteocytes

Question 17

canaliculi

Answer 17

tunnels between lamellae that allow osteocytes to receive nutrients

Question 18

four types of lamellae

Answer 18

outer circumferential - below periosteum
osteon - haversian system, functional unit of bone
interstitial - remnants of old osteons
inner circumferential - immediately along the endosteum

Question 19

osteon

Answer 19

Haversian canal surrounded by circular lamellae with lacunae connected by canaliculi

Question 20

Haversian canal

Answer 20

contains blood vessels

runs parallel to longitudinal axis of bone

Question 21

cancellous bone

Answer 21

spongy bones

• no haversian systems (no osten)
• have trabeculae and spicules
• lamellar structure

Question 22

Volkmann’s canal

Answer 22

vascular channels at right angles to connect osteon vessels

Question 23

periosteum

Answer 23

fibrous connective tissue sheath enveloping bone

• outer fibrous layer
• inner cellular layer
  
  • contains undifferentiated osteogenic cells
    
    • osteoprogenitor cells > osteoblasts > osteocytes

Question 24

sharpey’s fibers

Answer 24

anchor periosteum to underlying bone

-collagen fibers from outer periosteum layer embed in bone

Question 25

endosteum

Answer 25

thin cellular layer lining bony walls of adjoining marrow cavity

• line all bone cavities (haversian canals and marrow spaces)
• have osteogenic potential

Question 26

modulation

Answer 26

reversible change in cell function

Question 27

differentiation

Answer 27

irreversible change in cell

Question 28

osteoid

Answer 28

extracellular matrix of bone before it gets calcified

Question 29

osteoblasts

Answer 29

arise from mesenchymal cells(embryo) and osteoprogenitor cells(adult)

lay down new bone

osteoprogenitor:

- nucleus is away from bony surface bc secreting things
- cytoplasm basophilic (lots of acids > RNA )

Question 30

osteocytes

Answer 30

reside within lacunae

maintain health of bone

participate in Ca2+ and PO4- transport

Question 31

osteoclasts

Answer 31

large and multinucleated

though to arise from fusion of macrophages

bone resporption

Question 32

Howship’s lacunae

Answer 32

location of osteoclasts

Question 33

ruffled border

Answer 33

edge of osteoclasts

- lots of lysosomal vesicles and mitochondria
- increased surface are for resporption

Question 34

spicules

Answer 34

first deposition of bone
-spike - like a shard of new bone

multiple spicules merge into trabecule

Question 35

trabeculae

Answer 35

bony spicules radiation from ossification centers

-spicules which have merged

Question 36

mechanism of osteogenesis

Answer 36

intramembranous (mesenchymal)

endochondral

Question 37

intramembranous bone formation

Answer 37

mesenchymal

occurs in flat bones of skull
pre-existing cells - mesenchymal cells, fibrous CT (collagen type I)

1 mesenchymal cells cluster, proliferate, and enlarge
2 differentiate into osteoblasts- secrete matrix which calcififes
3 cells trapped in lacunae - become osteocytes

Question 38

endochoncral bone formation

Answer 38

occurs in long bones

1 start with cartilage
2 osseus cuff forms
3 calcification of midregion
4 death and resporption of central chondrocytes
5 blood bessels penetrate diaphysis - form marrow cavity
6 osteogenic cells migrate into cavity
7

Question 39

four zones of epiphyseal plate

Answer 39

zone of long bone growth during endochondral osteogenesis

1 zone of resting cartilage - pool of chondrocytes (collagen type II)
2 zone of proliferating cartilage (stacked nickels) - rapid proliferation
3 zone of hypertrophying cartilage - slow proliferation
-production of collagen type I and VEGF (vascular recruiter)
zone of calcifying cartilage
-chondrocytes degenerate
-cartilagenous matrix calcified
-osteoprogenitor cells arrive via new vasculature

(also, zone of resorption/ossification)
-osteoblasts develop on cartilage spicules > new bone!

Question 40

Process of Bone Healing

Answer 40

similar to osteogenesis

1 hyaline cartilage by chondrogenic cells
2 forms a callus
3 fracture heals, as new bony tissue laid down to replace cartilage

Question 41

Regulation of Bone Growth

Answer 41

both hormone control and calcium level

-

Question 42

3 ways to regulate Calcium metabolism

Answer 42

1 change in bone turnover
2 change in gut absorption
3 urinary secretion

Question 43

calcitonin

Answer 43

inhibits bone resorption
-inhibits osteoclasts

produced by parafollicular cells of thyroid gland
-increase in Ca2+ > release of calcitonin

Question 44

parathyroid hormone

Answer 44

increase resorption of calcium

affects osteoclasts indirectly

- binds osteoblasts and stimulates release of cytokine
- cytokine increases osteoclast activity

secreted by chief cells of parathyroid gland

Question 45

Vitamin D and Bone growth regulation

Answer 45

converted to circulating hormone
-calcitriol

regulate calcium and phosphate in blood stream
promotes calcium uptake in gut
produced in skin
ingested in food