Flashcards in bonezhisto Deck (22):
What do osteoblasts come from? Osteoclasts?
osteoblasts = mesenchymal stem cell
osteoclasts = hematopoietic stem cell
What is the one named sesamoid bone in the body?
others located in hands, feet (small bone surrounded by tendon)
What does the endosteum line?
All inner parts of the bone: canals, cavites. Only osteoprogenitor layer
What does the periosteum line?
The outer part of the bone. Made of a connective tissue layer and a osteoprogenitor layer
What produces osteoid?
osteoblasts NOT osteocytes
What makes up osteoid?
Type I collagen, bone matrix proteins (BMPs), GAGs
What makes up the inorganic part of bone?
What does osteocalsin do?
excreted by osteoblasts, promotes calcification
What are the two ways osteoblasts help promote calcification?
1. secretion of osteocalsin: brings calcium
2. secretion of alkaline phosphates: PO4- and Ca2+ make up HA
What do the cytoplasmic extensions of osteocytes travel through? How do they communicate?
travel through canaliculi, communicate through gap junctions
What are major differences between bone and calcified cartilage?
-type I collagen
-type II collagen
Another name for primary bone tissue
woven or immature bone
Another name for secondary bone tissue
lamellar or mature bone
Are spongy bone and compact bone the same histologically?
yes, both are lamellar
What is the structural unit of bone?
central canal contains artery/nerve
surrounded by concentric lamellae circles
What is the outer boundary of an osteon?
What are the vessels that run perpendicular to haversian canals, supplying the endosteum and periosteum?
What surrounds osteon?
(remnants of old osteons)
How are new osteons made?
1. Osteoclasts dig a canal
2. New blood vessel and osteoprogenitor cells move down into the new canal
3. Osteoblasts start forming new bone from the outside in
Does spongy bone contain osteons?
No, but it still has lamellae
How are cells in spongy bone supplied?
They are close to the bone marrow, so nutrients don't have to travel far.