Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
71 Cards in this Set
- Front
- Back
|
Special structure harbored within bone:
|
Bone marrow
|
|
|
what percent of body weight is bone marrow?
|
5%
|
|
|
What type of tissue is bone?
|
Specialized connective tissue - calcified ECM
|
|
|
Bone is a reservoir of:
|
-Calcium
-Phosphate |
|
|
What hormone induces bone resportion?
|
PTH
|
|
|
What acts in opposition to PTH?
|
Calcitonin
|
|
|
3 Cells in bone:
|
-Osteoblasts
-Osteocytes -Osteoclasts |
|
|
What activates osteoclasts?
|
PTH
|
|
|
WWhat are the 2 types of stuff in bone matrix? How much of each?
|
-inorganic - 70%
-organic - 30% |
|
|
What is the inorganic stuff?
|
Hydroxyapatite (Calcium + Phosphorus)
|
|
|
HHow much of the body's calcium is stored in bone?
|
99%
|
|
|
What is the organic stuff in the bone matrix?
|
-Type 1 collagen
-Proteoglycans -Glycoproteins |
|
|
What has more proteoglycans; cartilage or bone?
|
Cartilage
|
|
|
What is the function of glycoproteins in bone?
|
Promote calcification
|
|
|
Why is bone so hard?
|
Because it has BOTH hydroxyapatite and Collagen type 1
|
|
|
What are osteoblasts?
|
Specialized fibroblasts
|
|
|
What are the 2 known osteoblast specific genes?
|
-Cbfa-1
-Osteocalcin |
|
|
What is Cbfa-1 essential for?
|
Bone formation in the embryo
|
|
|
What proteins control the differentiation of fibroblasts into osteoblasts?
|
-BMPs
-Indian hedgehog |
|
|
What do osteoblasts secrete?
|
The bone matrix
|
|
|
What is the old name for bone matrix?
|
Osteoid
|
|
|
What type of collagen is in osteoid?
|
Type I collagen
|
|
|
What type of collagen is in cartilage (hyaline)?
|
Type II
|
|
|
How is bone growth COMPLETED?
|
By glycoprotein-mediated calcium deposition.
|
|
|
What happens if you don't have any hydroxyapatite?
|
NO WEIGHT BEARING (remember the bone demonstration)
|
|
|
What injection allows the monitoring of appositional bone growth?
|
Tetracycline
|
|
|
What is it called when calcification is impaired?
|
Osteomalacia
|
|
|
What is it called when osteoclasts destroy the bone matrix as it is made?
|
Osteitis fibrosa cystica
|
|
|
What are the mature cells that occupy lacunae in bone?
|
Osteocytes
|
|
|
Where are lacunae located in bone?
|
In lamellae
|
|
|
How many osteocytes per lacuna?
|
1
|
|
|
How do osteocytes communicate?
|
By sticking cytoplasmic processes out of the lacunae into canaliculi.
|
|
|
What allows osteocyte processes to join?
|
Gap junctions
|
|
|
What do osteocytes do with their connections to each other and blood vessel endothelial cells?
|
Nourish each other and maintain the bone matrix.
|
|
|
What is the function of osteoclasts?
|
To destroy and remodel bone
|
|
|
What are osteoclasts made from?
|
Fusion of macrophages into a multinuclear cell.
|
|
|
What spaces do osteoclasts occupy within bone?
|
Howship's lacunae
|
|
|
What feature of osteoclasts allows them to attach to the ECM to chow down on bone?
|
a RUFFLED BORDER
|
|
|
What is the function of this ruffled border?
|
It forms a microenvironment that promotes bone resorption.
|
|
|
What cytokines activate osteoclasts?
|
PTH
|
|
|
What hormone inhibits osteoclasts?
|
Calcitonin
|
|
|
How do activated osteoclasts resorb bone?
|
By releasing acid which dissolves the hydroxyapatite and activates cathepsin-K
|
|
|
What is Cathepsin-K?
|
Lysosomal enzyme secreted by osteoclasts.
|
|
|
What disease has a high rate of abnormal osteoclast remodeling?
|
PAGET'S
|
|
|
What other non-inherited disease is due to osteoclast activity?
|
Osteoporosis
|
|
|
What are 2 different types of bone?
|
-Compact
-Spongy |
|
|
Is there any microscopic structural difference in compact and spongy bone?
|
NO
|
|
|
What are the 2 important features of long bones?
|
-Diaphysis (shaft)
-Epiphysis (ends) |
|
|
What type of bone is the diaphysis made of?
|
compact, but with spongy lining the marrow
|
|
|
What type of bone is the epiphysis made of?
|
Spongy bone with caps of compact.
|
|
|
What are Flat bones constructed out of?
|
2 compact bone plates surrounding a diploe - area of spongy bone.
|
|
|
What is the structural subunit of bone called?
|
an Osteon
|
|
|
What canals interconnect adjacent lamellae in osteons?
|
Volkmann's canals
|
|
|
Are Volkmann's canals connected to the Haversion canal?
|
Yes.
|
|
|
What resides in Haversian and Volkmann's canals?
|
Blood vessels, nerves, and lymphatics.
|
|
|
What is the arrangement of collagen type I fibers in alternating lamellae in osteons?
Why? |
Antihelical - it gives the bone more strength in spite of it being so light.
|
|
|
What type of bone is in adults?
|
Secondary
|
|
|
What type of bone is in developing or regenerating bone?
|
Primary / Woven bone
|
|
|
How is secondary adult bone produced?
|
By resorption and remodeling of primary woven bone during development.
|
|
|
What are the 2 ways that bone develops?
|
1. Intramembranous
2. Endochondral |
|
|
What happens in intramembranous bone growth?
|
Osteoblasts deposit osteoid onto mesoderm.
|
|
|
What happens in endochondral bone growth?
|
osteoblasts deposit osteoid onto CARTILAGE
|
|
|
By what type of process do LONG ONES form?
|
Endochondral
|
|
|
By what type of process do FLAT bones form?
|
Intramembranous
|
|
|
Where does the bone form during intramembranous ossification of flat bones?
|
In ossification CENTERS
|
|
|
Onto what type of cartilage is osteoid deposited during long bone endochondral ossification?
|
onto HYALINE cartilage
|
|
|
What is the first step in endochondral ossification?
|
1. Formation of a BONE COLLAR around perichondrium of the future diaphysis
|
|
|
What happens after the bone collar forms?
|
Hypertrophy and apoptosis of the cartilage cells surrounded by the bone collar.
|
|
|
What are the 2 prominent processes that then occur in endochondral ossification?
|
-Bone production on the calcified cartilage matrix (by osteoblasts)
-Cavitation of the bone marrow |
|
|
How is the process of endochondral ossification different at the epyphysis?
|
Some hyaline cartilage is retained as Articular Cartilage and Epiphyseal plate cartilage.
|
|
|
Why is it important that Epiphyseal plate cartilage be retained?
|
Because that's where the bone grows in length.
|
