MSK 02 - Bone-I Flashcards
Discuss the basic composition of bone ECM
What do osteoblasts do? What cells do they arise from?
Osteoblasts secrete the osteoid (the organic unmineralized bone ECM) and they arise from the osteoprogenitor (osteogenic) cells.
Describe some visually distinguishing characteristics of osteoblasts.
They are basophilic
May appear as a cuboidal layer (if highly active) or flattened (if less active)
Cytoplasmic processes contact them with other osteoblasts or osteocytes
They possess PAS positive granules that are most likely the precursors of the glycosaminoglycans of the osteoid matrix
What is bone lacuna? What is a bone canaliculus?
Bone Lacuna - a small space containing an osteocyte in bone
Bone Canaliculus - microscopic canals between the lacunae of ossified bone.
What are osteocytes? What do they do? What are some of their distinguishing characteristics?
Osteoblasts that become entrapped in their own matrix (lacunae).
They help to maintain bone tissue by maintaining communication, and exchanging nutrients and metabolites via gap junctions between their narrow cytoplasmic processes extending through the canaliculi
They have increased amounts of condensed nuclear chromatin, reduced amounts of RER and a smaller Golgi vs osteoblasts
How are osteoclasts formed and where are they found?
How are Howship’s lacunae formed?
By the osteolytic activity of osteoclasts
Discuss the three distinct regions of the osteoclasts.
Discuss the process of bone resorption.
What are osteogenic cells? Where are they found? What do they do? What do they arise from?
What are bone lining cells? Where are they found? What is their function?
What are the periosteum and endosteum?
They are non-calcified connective tissue layers that cover the external (periosteum) and internal (endosteum) surfaces of the bone, except over articular surfaces.
Discuss the composition of the periosteum and endosteum.
Facts to know about bone growth
What is immature bone? What are some other names for immature bone?
What is mature bone? What are some other names for mature bone?
Immature bone
Mature bone
What are the two types of mature bone? Briefly describe them.
What is the functional unit of compact bone?
The Haversian system or Osteon which is 4 to 20 concentric layers of compact bone tissue (aka lamellae) in a cylindrical shape with numerous canaliculi to permit communication and a central Haversian canal that carries blood vessels and nerves.
Are the Haversian systems in parallel? Why or why not?
What does each lamella of compact bone consist of?
Multiple parallel arrays of collagen fibers. Adjacent lamellae have alternating directions of collagen fibers providing great strength despite its light weight.
Facts to know about the circumferential lamellae.
What are Volkmann’s canals? What is their purpose?
- Osteon
- Haversian Canal
- Volkmann’s Canal
- Circumferential Lamellae
- Insterstitial Lamellae
- Osteocytes
- Endosteum
- Canaliculi
