07a: Bone Histogenesis Flashcards
List the bone cell types. Put a star after the ones that are simply different forms of the same cell.
- Osteoblast*
- Osteocyte*
- Osteoprogenitor cell*
- Bone lining cell*
- Osteoclast
Principal cell of bone formation:
Osteoblast
Osteoblasts can be found on the (X) surface of bone. They function as (independent/interconnected) cells.
X = free;
Interconnected
(X) are capable of (Y) osteolysis. With this process, they’re managers of (Z).
X = osteocytes Y = osteocytic Z = bone's Ca reservoir
(Osteoblasts/osteocytes) are interconnected via (X).
Osteoblasts and osteocytes;
X = gap junctions
(X) synthesize the osteoid, aka (Y).
X = Osteoblasts Y = organic material of bone
Describe process of (X) transitioning into osteocyte.
X = osteoblast;
Changes polarity, secretes matrix on its free surface, and becomes entrapped in lacunae
(X) are quiescent osteocytes.
X = bone lining cells
Osteoprogenitor cells are found in/on:
- Bone marrow cavity
2. Inner cell layer (cambium) of periosteum
Which event(s) would lead to osteocytic osteolysis?
Decrease in serum Ca levels
The dendrites of (X) reside in (Y), which are filled with (Z).
X = Osteocytes Y = canaliculi Z = canalicular (tissue) fluid
Most, (X)%, of the surface of our bones are covered by:
X = 90
Bone lining cells
How can (X) bone cells detect pressure changes?
X = osteocytes;
Hair-like projections (transducers) extend from dendrites to walls of canaliculi and detect changes in fluid
Osteocytes interconnect with:
- Osteocytes
- Osteoblasts
- Blood vessels
Outer layer of periosteum consists of:
- Fibroblasts
2. Type I collagen
Inner layer of periosteum, aka (X), consists of
X = cambium
Osteoprogenitor cells
Osteoprogenitor cells are (X)-potent. They can become:
X = bi
Fibroblasts or osteoblasts
Principal cell of bone resorption:
Osteoclast
Osteoclast formed by:
Asynchronous fusion of monocyte progenitor cells
List the membrane domains in osteoclast.
- Ruffled border
- Sealing zone
- Basal (anti-resorptive) zone
Ruffled border of osteoclast contains:
- Proton pumps (pump H+ into Howship’s lacuna)
2. Cl channels
Sealing zone of osteoclast contains:
Rich in actin and integrins (link to bone)
Basal zone of osteoclast contains:
Cl/HCO3 exchangers
Cl is entering osteoclast at (X) and leaving osteoclast at (Y).
X = basal zone Y = ruffled border
Which key enzyme in (X) cell allows for bone resorption? What does it (degrade/form)?
X = osteoclast
Carbonic anhydrase; produces H+ and HCO3-
Which ion(s) are pumped into Howship’s lacuna?
H+ and Cl-
Mineral component of bone removed by (X). Organic component degraded by (Y).
X = acid environment Y = lysosomal cathepsins, collagenases, metalloproteinases
What are the forms of bone histogenesis?
- Intramembranous
2. Endochondral
Intramembranous bone formation is:
Direct transformation of condensed mesenchyme
What are some characteristics of the (X) tissue in which intramembranous bone formation occurs?
X = connective
Primitive, highly vascularized
In intramembranous bone formation, (X) cells lay down (Y) in locations equidistant between (Z).
X = osteoblasts Y = osteoid Z = cappilaries
T/F: In intramembranous bone formation, some stem cells are retained.
True
Primary (X) bone grows (more/less/equally as) rapidly than secondary (Y) bone.
X = immature, Woven Y = mature, Lamellar
More
(Woven/lamellar) bone is more cellular.
Woven
(Woven/lamellar) bone resorbs more slowly.
Lamellar
(Woven/lamellar) bone has more collagen.
Lamellar
(Woven/lamellar) bone has more ground substance.
Woven
(Woven/lamellar) bone mineralizes more rapidly and (more/less) completely.
Woven; less
Give examples of bone that forms via intramembranous bone formation.
Flat bones in head, maxilla, mandible, scapula
Endochondral bone formation is:
bone formation in cartilage model
Give examples of bone that forms via endochondral bone formation.
Weight-bearing axial and limb bones
List the tasks of chondrocytes in endochondral bone formation.
- Increase local concentrations of PO4- and Ca
- Remove inhibitors of mineralization
- Provide means to precipitate and bind mineral
Which ion(s) is/are important in endochondral bone formation? Explain.
PO4- and Ca; bind matrix vesicles (that bud from chondrocyte membrane) and generate crystals
In endochondral bone formation, what’s the source of free crystals that bind to (X) fibers?
X = type 10 collagen
Matrix vesicles, with accumulated crystals, break apart and leave crystals in matrix
Which fiber type(s) are important in mineralization during endochondral bone formation?
- Type 10 collagen (binds crystals)
2. Type 2 collagen (bound by Type 10)
In endochondral bone formation, the (X) chondrocyte synthesizes:
- Type 10 collagen
- Alkaline phosphatase
- Pyrophosphatase
In endochondral bone formation, once the blood vessel comes into (cartilage/bone), it brings along:
Bone;
- Osteoprogenitor cells
- Hematopoietic SC
Primary ossification center forms in (X).
X = diaphysis (central part of long bone)
Secondary ossification center forms in (X).
X = each epiphysis (end of long bone)
T/F: Both ossification centers form pre-natally.
False - secondary ossification center forms post-natally
Bone fracture healing involves (X) bone formation.
X = both endochondral and intramembranous
First step of fracture healing:
Formation of hematoma (clot)
Second step of fracture healing: Once (X) forms, (Y) begin to regenerate and, thus, (Z) become available.
X = fibrocartilaginous (soft) callus Y = blood vessels Z = osteoblasts (formed from cells of endosteum and periosteum)
Why/where is endochondral bone formation necessary in bone fracture repair?
Middle of bone (blood vessels take awhile to grow into middle)
Third step of fracture healing:
Bony (hard) callus forms
Final step of fracture healing:
Bone remodeling (lamellar bone replaces woven bone)
Why is the bony callus (small/large) in diameter?
New woven bone lacks strength of lamellar bone, so makes it up by increasing diameter of callus
