bone histology

Question 1

bone histology cells

Answer 1

osteoblasts: make matrix
osteocytes: entrapped in matrix
osteoclasts: break down old matrix, so new matrix can replace it

Question 2

matrix (concrete)

Answer 2

hydroxyapatite: 65%
-gives bone hardness
-gives weight-bearing strength
-calcium phosphate crystals

Question 3

matrix (metal rods)

Answer 3

collagen fibers:
-forms framework in which hydroxyapatite salts are deposited
-gives bones flexibility
-resistance to being stretched or torn apart

Question 4

osteoblasts

Answer 4

-bone building cells that make and secrete collagen fibers
-initiate calcification
-surround themselves with matrix and become osteocytes

ossification=formation of new bone by osteoblast

Question 5

osteocytes

Answer 5

-MOST ABUNDANT; found in lacunae (canaliculi=tiny channels that connect lacunae)
-mature bone cells surrounded by matrix
-main function: maintain bone tissue; through exchange of nutrients w blood
-connected by gap junctions which allow passage of nutrients&signals

Question 6

osteoclasts

Answer 6

-“bone destroying”
-multinucleated cells that break down bone matrix→resorption
-release stored calcium and phosphorus into circulation

Question 7

two types of bone formed during ossification

Answer 7

woven bone: immature bone
-collagen fibers disorganized
-woven bone remodeled→lamellar bone

lamellar bone: mature bone
-concentric sheets/layers = lemellae
-fibers organized
-osteocytes arranged in layers sandwiched between lamellae

Question 8

two types of lamellar bone

Answer 8

spongy (cancellous):
-numerous branching bony plates=trabeculae
-red bone marrow fills space between trabeculae

compact:
-solid outer layer
-more matrix and is denser

Question 9

compact bone

Answer 9

composed of repeating units called OSTEONS:
-lamellae around a central canal PARALLEL

perforating (volkmann’s) canals:
-carry blood cells PERPENDICULARLY; connect with central canals