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Flashcards in Bone Developmental Disorders- Handorff Deck (48)
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1

What is osteoid

All of the inorganic matrix that is laid down beore bone is mineralized

2

What are the active cell types in bone?

Osteoprogenitor cells
Osteoblasts, Osteocytes, Osteoclasts

3

What are osteoprogenitor cells?

Pluripotent mesenchymal stem cells

4

What can drive osteoprogenitor cells into becoming osteoblasts?

CBFA-1 stimulation

5

Osteoblasts do what

form bone

6

Osteoclasts

degrade bone

7

Osteocytes

Sense mechanical stress and regulate serum calcium and phosphate

8

What bone cell synthesizes osteoid?

Osteoblasts

9

What is osteoid

Type I Collagen which makes up about 90% of the 35% organic bone

10

Osteoblasts mediate osteoclast activity, they hyave PTH receptors

true. this can be significant during diseases such as hyperparathyroidism where too much PTH is developed

11

Remember that in certain diseases, the communication between osteoblasts and osteoclasts is screwed up

ok

12

Osteocytes are encased in?

Lacunae?

13

How do osteocytes communicate?

Through canaliculi

14

What do osteoclasts do?

remodel and resorb bone

15

Osteoclasts require what cytokines for differentiation?

IL-1, IL-3, IL-6, IL-11, GM-CSF, M-CSF

16

Osteoclasts reside where?

Howship Lacunae

17

What do osteoclasts look like?

Multinucleated

18

How does Osteoclast differentiation occur?

Osteoclasts are derived from the same cells that make macrophages. RANK ligand binds to RANK receptor. This occurs in the background of M-CSF and causes precursor cells to produce functional osteoclasts.

19

What is OPG

Osteoprotegrin, It protects bone from resorption by acting as a decoy receptor for RANKL, preventing it from binding the RANK receptor on osteoclast precursors.

20

Osteogenesis Imperfecta is a ------- of diseases which share common mutatins in what?

family, type 1 collagen

21

Type 1 OI...

Make too little pro-alpha1. Normal stature, lax joints, deafness

22

Type 2 OI

Pro-alpha 1 is too short, collagen is made but degraded intracellularly. The bones break in utero which kills the child

23

Type III

Triple Helix doesn't form well.
Child is short, many fractures, kyphosis, hard of hearing, bad cases are lethal

24

Type iV

Pro alpha 2 is too short, short stature, somewhat fragile bones.

25

OI is usually autosomal ...... except for........

dominant, type II (either auto recessive or new autosomal dominant

26

What are the four major clinical criteria for OI

osteoporosis, blue sclerae, dentigenesis imperfecta, premature otosclerosis
Must have two of these for clinical diagnosis

27

Blue sclerae are associated with

heritable disorders of connective tissue. They appear predominantly in OI and to a lesser extent in pseudoxanthoma elasticum, Ehlers Danlos, Marfan disease

28

Why are the sclera blue?

The sclera are so thin that the underlying choroid is visible

29

What are the two types of OI?

Congenita- bad, Tarda- not as bad

30

Achondroplasia is autosomal.....

dominant