Physiology of bone repair Flashcards
Label the long bone components using the labels below:
periosteum articular cartilage compact bone epiphyseal line spongy bone medullary cavity endosteum
1 = articular cartilage 2 = spongy bone 3 = epiphyseal line 4 = periosteum 5 = compact bone 6 = medullary cavity 7 = endosteum
There are 2 types of bone that make up the bone we know, which come under the category of lamella. The outer layer and the inner layer. What are these layers called?
- outer layer = compact bone
- inner layer = trabecular bone
What is an osteon?
- rod like unit, with lots of them making up bones
- main structural component of compact bones
- contain circular lamella within and then a haversham canal in the middle
Osteons are the main structural component of compact bones. There are 3 main cell types contained within osteons, what are they?
1 - osteoblasts
2 - osteoclasts
3 - osteocytes
What is the basic function of osteoblasts, osteoclasts and osteocytes?
- osteoblasts = re-build bone
- osteoclasts = degrade bone
- osteocytes = nutrition and bone formation
Lamella are a key component of bones, what are lamella?
1 - form of bone cell
2 - organised sheets of mineralised osteoid
3 - spaces containing osteocytes
4 - communication channels between osteocytes
2 - organised sheets of mineralised osteoid
At the centre of the osteon is a canal that carries VAN (veins, arteries and nerves). What is this canal called?
1 - dystrophian canal
2 - Eusabian canal
3 - Volkmann canal
4 - Haversian canal
4 - Haversian canal
Bones contain canaliculi, what are these?
1 - form of bone cell
2 - organised sheets of mineralised osteoid
3 - spaces containing osteocytes
4 - canals used for communication between osteocytes
4 - canals used for communication between osteocytes
Lacunae are contained within osteons. What are lacunae?
1 - form of bone cell
2 - organised sheets of mineralised osteoid
3 - spaces containing osteocytes
4 - canals used for communication between osteocyte
3 - spaces containing osteocytes
- lacunae are connected by canaliculi
Which location on the bone would you find the majority of trabecular bone?
1 - epiphysis
2 - diaphysis
3 - periosteum
4 - epiphyseal plate
1 - epiphysis
Which location on the bone would you find the majority of compact bone?
1 - epiphysis
2 - diaphysis
3 - periosteum
4 - epiphyseal plate
2 - diaphysis
There is a dense fibrous connective tissue lining the outside of the bone and the medullary cavity of the bones. What are these 2 layers called and where are they located?
1 - epimysium and endosteum
2 - perimysium and endosteum
3 - endosteum and periosteum
4 - periosteum and epimysium
3 - endosteum and periosteum
- outer layer of bone = periosteum
- medullary layer = endosteum
What is bone homeostasis?
- balance between bone breakdown and bone re-absorption
Osteoclasts are a cell in bones responsible for bone breakdown. What is the origin of this cell type?
1 - progenitor cell
2 - hematopoietic stem cell
3 - red blood cells
4 - immature osteocytes
2 - hematopoietic stem cell
- form from multiple monocytes
Osteoblasts are a cell in bones responsible for building bone. What is the origin of this cell type?
1 - progenitor cell
2 - hematopoietic stem cell
3 - red blood cells
4 - immature osteocytes
1 - progenitor cell
- originate from mesenchymal cells
What is the primary type of collagen that we can find in bone?
1 - type I
2 - type II
3 - type III
4 - type IV
1 - type I
What are 3 main components that make up the inorganic matrix of bone that is mineralised, accounting for 70% of bone?
1 - Ca2+ + Cl- ions + Na+ ions
2 - Ca2+ + phosphate + hydroxyl ions
3 - Ca2+ + phosphate + K+ ions
4 - Ca2+ + phosphate + Cl- ions
2 - Ca2+ + phosphate + hydroxyl ions
During bone formation, does bone begin as organic or inorganic?
- begins as organic
- undergoes calcification and then becomes inorganic
The 3 main components that make up the inorganic matrix of bone that is mineralised, accounting for 70% of bone are Ca2+ + phosphate + hydroxyl ions. What is the name given to this structure?
1 = hydroperoxide 2 = hydroxyapatite 3 = calcium phosphate 4 = calcium hydroxylate
2 = hydroxyapatite
Once osteoclasts break down bone, there is something contained within bones that become visible to osteoblasts that then facilitate bone growth and development. What is contained within the bone extracellular matrix that facilitates this bone growth?
1 - Ca2+
2 - growth factors
3 - growth factor inhibitors
4 - osteocytes
2 - growth factors
Which type of bone cell when mature becomes trapped in bone extracellular matrix and becomes an osteocyte?
- osteoblasts
Progenitor cells, which will go onto develop into osteoblasts are contained within bones. Where are they contained within the bones?
1 - endosteum
2 - periosteum
3 - periosteum + endosteum
4 - medullary cavity
3 - periosteum + endosteum
Indian Hedgehog (IHH) is a growth factor involved in what?
- bone reformation
The Wingless-related integration site (WNT) is a pathway that has been heavily kinked with the growth and development of what?
- bone growth and development
Bone morphogenic proteins (BMP) are growth factors that have been heavily kinked with the growth and development of what?
- bones
Fibroblasts growth factors are growth factors that are heavily involved in the growth and development of what inorganic structure?
- bone
There are 4 main stages of bone remodelling. Label the image below using these labels:
reabsorption
formation
reversal
quiescence
1 = reabsorption 2 = reversal 3 = formation 4 = quiescence
The 1st stage of bone formation is reabsorption. What is is this stage?
1 - osteoclasts degrade bone, Ca2+ and P released into blood
2 - osteoclast degrade bone, Ca2+ and phosphate remain in bones
3 - osteoclasts degrade bone, Ca2+ and P released into blood
3 - osteoblasts degrade bone, Ca2+ and P released into blood
1 - osteoclasts degrade bone, Ca2+ and P released into blood
The 2nd stage of bone formation is reversal. What is is this stage?
1 - degraded extracellular matrix is recycled to rebuild bone
2 - degraded extracellular matrix is used as energy by osteoblasts
3 - degraded extracellular matrix by osteocytes is removed by macrophage
4 - degraded extracellular matrix by osteoclasts is removed by macrophage
4 - degraded extracellular matrix by osteoclasts is removed by macrophage
The 3rd stage of bone formation is formation. What is is this stage?
1 - growth factors activate osteoblasts and new bone formation begins
2 - growth factors activate osteocytes and new bone formation begins
3 - growth factors inhibit osteoclasts and macrophages
4 - growth factors stimulate osteocytes to stimulate osteoblasts
1 - growth factors activate osteoblasts and new bone formation begins
- osteocytes are formed when osteoblasts get trapped in bone matrix
Once new bone has been formed, what is the final stage of bone remodelling?
1 - recycling phase
2 - remodelling phase 2
3 - quiescent stage
4 - bone re-formation stage
3 - quiescent stage
We distinguish between new and old bone as new bone contains what?
1 - cement line
2 - osteocytes
3 - osteoclasts
4 - macrophages
1 - cement line
- cement line is where new bone has been deposited but high in collagen as not that mineralised yet
What cell type in bones act as a mechanoreceptors that are able to detect that bones are undergoing mechanical force and therefore need to strengthen?
1 - macrophages
2 - osteocytes
3 - osteoclasts
4 - osteoblasts
2 - osteocytes
When a bone is fractures, what is the first thing that happens inside the bone to begin the bone repair process?
1 - ischaemia
2 - osteoblast activation
3 - release of growth factors
4 - haematoma
4 - haematoma
- bleeding outside of blood vessels into bones following by inflammation with macrophages
Once the bone is fractured and haematoma, bleeding outside of blood vessels into bones following by inflammation with macrophages has occurred there will be the formation of the first type of tissue. This is the first stage of recovery following tissue damage. What is this tissue called?
1 - quiescence
2 - granulation
3 - reversal
4 - bone reformation
2 - granulation
- fibrin and fibroblasts migrate to the area and are deposited
With any tissue damage there will also be tissue debris. What cell type will migrate to the area and remove the damaged tissue?
1 - T cells
2 - macrophages
3 - platelets
4 - dendrites
2 - macrophages
What is osteoid and osteon?
- osteoid = unmineralised bone tissue (collagen, fibrous tissue, polysaccharides etc…)
- osteon = mineralised bone (rod like structures that make up the main structural component of bone)
During weeks 2-3 following a bone fracture osteoblasts will be activated by growth factors released from the extracellular matrix of the bone. What will osteoblasts begin to deposit at the ends of the broken tissue?
1 - lacunas
2 - phosphate
3 - osteoid seam
4 - Ca2+
3 - osteoid seam
- mainly collagen acting like a scaffold for Ca2+ and phosphate to be deposited
During weeks 2-3 following a bone fracture osteoblasts will be activated by growth factors released from the extracellular matrix of the bone. Osteoblasts begin to deposit osteoid seam (collagen like scaffold for new bone) at the ends of the broken tissue, forming what?
1 - articular cartilage
2 - macrophages
3 - soft callus
4 - osteocytes
3 - soft callus
- formed of woven bone and hyaline cartilage
During weeks 2-3 following a bone fracture osteoblasts will be activated by growth factors released from the extracellular matrix of the bone. Osteoblasts begin to deposit osteoid seam at the ends of the broken tissue called soft callus. Between 4-16 weeks, this soft callus then becomes what?
1 - articular cartilage
2 - macrophages
3 - hard callus
4 - osteocytes
3 - hard callus
During bone repair, is the bone initially laid down compact or trabecular?
- trabecular
- eventually replaced by compact bone
What is 1,25-Dihydroxyvitamin D?
- molecular active form of vitamin D
What affect does parathyroid hormone have on bones?
- binds to osteoblasts and that then releases RANK-L and Macrophage-Colony Stimulating Factor (M-CSF)
- M-CSF and RANK-L stimulate macrophages then form multi nucleated osteoclasts
- osteoclast degrade bone and release Ca2+ and phosphate into blood
What affect does the active form of vitamin D have on bones?
- binds to vitamin D receptors on osteoblasts
- osteoblasts then secrete M-CSF and RANK-L
- M-CSF and RANK-L stimulate macrophage pre-cursors to form multi-nucleated osteoclasts
- osteoclasts degrade bone releasing Ca2+ and phosphate
What affect does parathyroid hormone have on the kidneys?
- binds to proximal convoluted tubules
- inhibits re-absorption of phosphate
- binds to principle cells and increases Ca2+ reabsorption
What affect does parathyroid hormone have on the vitamin D levels?
- converts inactive vitamin D into its active form
What affect does vitamin D have on the GIT?
- enters enterocytes
- increased Ca2+ and phosphate absorption from food
Which hormone is produced by the C cells of the thyroid and is important for regulating Ca2 levels?
1 - calcitonin
2 - parathyroid hormone
3 - thyroid hormone
4 - inactive vitamin D
1 - calcitonin
Calcitonin is a hormone is produced by the C cells of thyroid and is important for regulating Ca2 levels. How does this hormone regulate Ca2+ levels?
- binds and inhibits osteoclasts, inhibiting bone breakdown
Once parathyroid hormone bind with osteoblasts they initiate the release of macrophage-colony stimulating factor (M-CSF) and RANK-L, which stimulate the maturation of osteoclasts that initiate bone degradation. What cytokine does PTH inhibit the release of from osteoblasts, that would inhibit osteoclasts?
1 - osteoprotegerin
2 - calcitonin
3 - osteoid seam
4 - IL-2
1 - osteoprotegerin
- osteoprotegerin is normally released from osteoblasts when osteocytes have finished doing their jobs
Once PTH has bound to osteoblasts and they have released cytokines RANK-L and M-CSF. What do these 2 cytokines then do?
- stimulate pre-osteoclasts forming mature osteoclasts
Osteoclasts contains lysosomes and a ruffled surface, what is important about these 2 features?
1 - ensure immune cells cannot phagocytose them
2 - ensure bone degradation is efficient
3 - limit bone degradation
4 - able to degrade osteoblasts
2 - ensure bone degradation is efficient
- lysosomes contain hyaluronic acid for degrading bone
- ruffled surface provides increased surface area for bone breakdown
What was the diagnosis of hypercalcaemia given in the lecture?
1 - 0.15mg/100ml
2 - 15mg/100ml
3 - 1.5mg/100ml
4 - 150mg/100ml
2 - 15mg/100ml
What is the difference between rickets vs osteomalacia?
- rickets = impaired bone mineralisation in children
- osteomalacia = impaired bone mineralisation in adults
When a bone is placed under stress micro-cracks may appear. Osteoblasts then secrete what that is able to stimulate nearby monocytes into differentiating into osteoclasts?
1 - IL-2 and M-CSF
2 - M-CSF and IL-6
3 - RANK-L and M-CSF
4 - IL-6 and RANK-L
3 - RANK-L and M-CSF
When a bone is placed under stress micro-cracks may appear. Osteoblasts then secrete RANK-L and M-CSF, which bind with the receptors on which cell of myeloid cell lineage?
1 - monocytes
2 - macrophage
3 - neutrophil
4 - basinophil
1 - monocytes
When a bone is placed under stress micro-cracks may appear. Osteoblasts then secrete RANK-L and M-CSF, which bind with the receptors on monocytes. The RANK-L and M-CSF then stimulates these monocytes and they fuse together to form what type of cell?
1 - giant cell
2 - macrophage
3 - osteoclast
4 - osteoblast
3 - osteoclast
- these can then degrade bone, releasing Ca2+ and phosphate into the blood
https://www.youtube.com/watch?v=Ei4seya3dOg
In order to control the level of RANK-L and M-CSF released by osteoblasts and ensure there is not too much osteoclasts activity, what else do osteoblasts secrete that is able to bind with RANK-L and M-CSF, inhibiting their ability to bind with further receptors on monocytes?
1 - IL-2
2 - osteoprotegerin
3 - M-CSF
4 - TNF-a
2 - osteoprotegerin
- act to inhibit RANK-L and M-CSF
Once osteoclasts have completed their function, and osteoprotegerin have been able to inhibit RANK-L, how are osteoclasts removed?
1 - become monocytes again
2 - engulfed by macrophages
3 - undergo apoptosis
4 - embedded in bone matrix
3 - undergo apoptosis
Once osteoclasts have completed their function, and osteoprotegerin have been able to inhibit RANK-L, osteoblasts begin laying down osteoid seam. What is then deposited on the osteoid seam that will form hydroxyapatite?
1 - Cl- and phosphate
2 - Ca2+ and phosphate
3 - K+ and phosphate
4 - Na+ and phosphate
2 - Ca2+ and phosphate
If an osteoblasts gets trapped in the bony matrix that is being laid down, what do these osteoblasts then become?
- osteocytes
