Bone (L4) Flashcards
Which bone cells secrete the organic component of the ECM?
Osteoblasts
Which bone cells are found in the CT lining bone tissue?
Osteogenic cells
Name the CT that lines the bone tissue externally
Periosteum
What is the origin of osteoblasts
Osteoprogenitor cells
What are the organic components of bone matrix?
Collagen type I
Proteoglycans
Glycoproteins such as osteonectin
Identify the cell:
- Simple, Cubiodal
- Polarized
- Abundant rER, free ribosomes and Golgi bodies
- Form gap and adherent junctions
Osteoblasts
What is the origin of bone lining cells?
Osteoblasts
What is the origin of osteocytes?
Osteoblasts
Which of the bone cells is responsible for deposition of inorganic matrix?
Osteoblasts
What is the fate of most osteoblasts?
Apoptosis
Which of the bone cells is responsible for secreting the osteoid?
Osteoblasts
What is the name of the collagen-rich material secreted by osteoblasts?
Osteoid
What is the name of the vitamin K dependent polypeptide secreted by osteoblasts?
Osteocalcin
Name the polypeptide that concentrates Calcium in the bone matrix
Osteocalcin
Which of the bone cells is responsible for secreting alkaline phosphatase vesicles?
Osteoblasts
What is the function of alkaline phophatase?
Increases the local concentration of PO43-
Hydroxyapatite crystals are formed around ____________
Alkaline phosphatase vesicles
After the formation of hydroxyapatite crystals, what is required to complete the calcification of the bone?
Deposition of more minerals, collagen and proteoglycans
Which of the bone cells is most abundant?
Osteocytes
Which of the bone cells are entrapped in the bone matrix?
Osteocytes
Which of the bone cells are found in howship lacunae?
Osteoclasts
Identify the cell:
- Almond shaped
- Inactive nucleus with condensed chromatin
- Little rER, ribosomes and small Golgi body
- Long dendritic processes running in canaliculi
Osteocytes
What is the mechanostat of bone formed of?
Osteocytes and their long dendritic processes running in canaliculi forming gap junctions with neighbouring cells
What is the function of the mechanostat?
Maintain bone matrix and adjust ion levels accordingly
What is the effect of lack of exercise on bone?
Wearing of the mechnostat leading to decreased bone density
Rapid bone resorption occurs after the death of which bone cells?
Osteocytes
Which cells serve as detectors for the activity of osteoblasts and osteoclasts?
Osteocytes
Diffusion of metabolites from blood vessels occurs through the processes of which bone cells?
Osteocytes
Which bone cells express proteins to control bone remodelling?
Osteocytes
What is the origin of osteoclasts?
Monocytes
Identify the cell:
- Large
- Multinucleated
- Motile
- Abundant lysosomes
- Ruffled border
Osteoclasts
Which of the bone cells functions in bone resorption?
Osteoclasts
Sharpey’s fibers are found in the
A/ Periosteum
B/ Endosteum
Periosteum
Which of the following bone CT is formed of 2 layers: outer fibrous and inner cellular?
A/ Periosteum
B/ Endosteum
Periosteum
Which of the following bone CT lines the bone marrow and trabeculae
A/ Periosteum
B/ Endosteum
Endosteum
What is the function of Sharpey’s fibers?
Binding periosteum to bone
The inner periosteum contains:
Osteoblasts
Osteoprogenitor cells
Bone lining cells
Which of the bone cells is involved bone growth and repair?
Osteoprogenitor cells
The inorganic components of bone are
- Calcium hydroxyapatite
- Non-crystalline Calcium Phosphate
- Sodium
- Magnesium
- Postassium
- Citrate
- Bicarbonate
What are the 4 types of lamellae in lamellar bone?
- Concentric lamellae around the Haversian canal
- Interstitial, irregular lamellae between osteons
- External circumferential lamellae beneath the periosteum
- Internal circumferential lamellae lining the bone marrow cavity
What are lamellae?
Parallel sheets of collagen type 1
What is the structure found at the centre of a Haversian system?
Haversian, central canal
What would you find between the successive layers of concentric lamellae?
Osteocyte lacunae
What is the cement line?
Outer boundary of an osteon containing collagen, other non-collagensous protein and minerals
Name the canals that communicate Haversian canals
Volkmann’s transverse perforating canals
Identify the tissue
- Non-lamellar bone
- Low mineral content
- High number of osteocytes
- Random arrangement of collagen type I fibers
Woven bone
State the location of woven bone
Embryo
Calvaria
Insertion of tendons
Callus (bone repair site)
Temporary bone is
- Lamellar
- Woven
Woven
How does bone remodelling occur?
Osteoclasts break down bone
Osteoblasts form new bone and deposit minerals in it
What happens when osteoclasts are overstimulated?
- Lose their mobility
- Increase resorptive activity
So they bore into one area of the bone
Instead of sweeping a large area
Name the hormone that stimulates osteoclasts
Parathyroid (Parathormone)
Name the hormone that inhibits osteoclasts
Osteocalcin
A patient arrives at the Emergency department after suffering a sudden fracture in his leg. He complains of severe pain. After many tests and a biopsy, the doctors determine that he suffers from osteosarcoma. This type of tumour originates in which bones cells?
Osteoprogenitor cells or osteoblasts
Osteoporosis is common in which patients?
Immobilised patients
Post menopausal women
Old people
What is the cause of osteoporosis?
Imbalance in bone turnover causing reduced bone mineral density
A genetic mutation that leads to defective collagen type I and brittle bones is a characteristic of which disease?
Osteogenesis imperfecta
Calcium or vitamin D deficiency in children causes which disease?
Rickets
Which vitamin is important for calcium absorption in the stomach?
Vitamin D
Epiphyseal plate distortion and bone deformities in children due to weight are characteristics of which bone disease?
Rickets
Calcium or vitamin D deficiency in adults causes which bone disease?
Osteomalacia
Deficiency in calcium in adult bones causes
Decalcification of existing bone
Deficient calcification of new bone
Softening of bones in adults is a characteristic feature of which bone disease?
Oseteomalacia
What are the effects of Softening of bones in osteomalacia?
Increased tendency of both major and minor fractures causing pain
