11/17 Histo of Bone Flashcards
The function of bone:
Levers for movement. support and protection. hematopoiesis in marrow, store and regulate serum levels of calcium and phosphate.
The two types of bones depending on the density
spongy bone and compact bone….
Describe the outer wall of bones
compact or cortical bone
what type of bone is the interior of bone made of?
trabecular (spongy, cancellous) bone and marrow
I am looking really close at compact and spongy bone samples…how can I distinguish the two? (microscopic scale)
compact and trabecullar bones are identical at the microscopic level…so good luck buddy!
the covering of bone surfaces…
connective tissue: periosteium on the outside and endosteum on the internal surface and long bones have Articular cartilage at the joints
Source of nutrition and progenitor cells for making bone:
periosteum and endosteum
found on the ends of long bones:
articular cartilage (no periosteum
two types of bone cell lineages:
undifferentiated mesenchymal cells and hematopietic stem cells
What is the family lineage of bone cells that come from Undiferentiated mesencymal stem cells?
Messenchymal cells gives rise to Osteoprogenitor cells called an osteoblast that gives rise to osteocyte!
What is teh family lineage of bone cells that come from hematopoietic stem cells.
Hematopoietic stem cells produce monocytes that produce Osteoclasts (they also prodcue macrophages of course so osteoclasts and macrophages are like siblings…:-)
the progenitor cells in periosteum and endosteum:
osteoprogenitor cells (preosteoblast)
what do osteoprogenitor cells produce:
osteoblasts
Can osteoprogenitor cells move or divide?
yes they proliferate and circulate!
how could osteoblasts be connected to calcified vessels
they may circulate in and make cells that make calcium… thus the migration of calcium from the skeleton to the vessels!
what do osteoblasts do?
bone-forming cells that secrete osteoid (ECM) mineralize the matrix and do NOT divide
derived from osteoblasts and surrounded by bone matrix
osteocytes
the opening where the osteocytes sit
lucunae between layers (lamellae) of adult bone.
the principal cell in adult bone 95%
osteocytes
HOw is the ostyocyte like a spider?
they put out little legs from the lacunae, through canaliculi to form gap junctions with other cells around them.
How do ostyocytes communicate, and maintain the matrix of cells in the bone
form continuous system of cells thorghout the bone via gap junctions in canaliculi between cells.
what do the osteocytes do?
maintain the matrix: sense stress, communicate with other cells: THE CELLS THAT MAKE AND MAINTIAN BONE
The cells that take bone apart (resorb bone)
the osteoclasts
multinucleate cells that are derived form macrophages in the bone marrow.
osteoclast
the space that an osteoclast forms on the surface of bone
Howship’s lucunae
what happens in the howship’s lacunae?
Oseoclast excretes acid and lysosomal enzymes that take bone apart and release calcium
what regulates the actions of osteoclasts?
indirectly by parathyroid hormone (up regulate) and perhaps directly by calcitonin
The purpose of osteoclasts
bone turnover and Ca2+ regulation
what is the principle organic components of bone matrix?
collagen type I and GAGs and proteoglycans and a bunch of glycoproteins
what will all of the glycoproteins in the bone matrix do?
promote mineralization, serve as hormones as well!
what is an example of hormone from bone…
osteocalcin released when bone is turned over and is connected to type II diabetes
Inorganic components of bone:
Hydroxyapatite (calcium and phosphate in a molecule) and trace minerals