Mon and Wed - histology of bone

Question 1

What makes osteoid and what is it?

Answer 1

osteoblasts, it is the pre-bone

Question 2

How does PTH interact with bones?

Answer 2

PTH stimulates osteoblasts directly, which release osteoclast stimulating factor to stimulate osteoclasts resorb calcium from bone tissue.

Question 3

Where do osteocytes reside? Where do their filopodia?

Answer 3

in lacunae

in canaliculi

Question 4

How do osteocytes communicate?

Answer 4

gap junctions

Question 5

osteoclast

5 features

Answer 5

large, multinucleated
bone resorption
come from monocyte
amitotic (cell division via clevage of the nucleus without spindle formation)
lots of lysosomes

Question 6

Which bone cells have a “ruffled border”

why does it exist?

Answer 6

osteoclasts

membrane of the ruffled border pumps H+ into sub-osteoclastic compartment to lower the pH and liberate mineral, which enter the osteoclast and are delivered to capillaries.

Also secretes enzymes to degrade organic compounds of decalcified bone, which are endocytosed and put into capillaries.

Question 7

Where do osteoclasts reside?

Answer 7

howship’s lacunae

Question 8

Inorganic part of bone matrix

Answer 8

calcium phosphate

hydroxyapatite crystals

Question 9

organic component of bone matrix

Answer 9

type 1 collagen.

ground substance: chondroitin sulfate; keratan sulfate, hyaluronate

glycoproteins are used to bind things together.

Question 10

Two types of bone

Answer 10

synonyms: cancellous, spongy bone, trabecular: spicules (trabeculae) of bone form spongy network. INTERIOR

Compact - dense bone, EXTERIOR