Skeletal 1000ft review Flashcards
What gives rise to new bone
mesenchymal stem cells
what cells create new bone
osteoblasts
What boney cells are mechanoreceptors
osteocytes
What do osteoclasts do
reabsorb bone and assist with mineral homeostasis
What is the periosteum and what does it contain
covering of the bone than contains vasculature and nerves
What cells develop osteoblasts
osteoprogenator cells
How many layers make up the periosteum
2
What does the external layer of the periosteum contain
vasculature and nerves -> branch through volkman canals
What is the most sensitive area of bone
external layer of periosteum because of nerves
What does the internal layer of the periosteum contain
Osteoprogenitor cells
How is the internal layer of the periosteum attached to the bone
sharpey fibers
What makes up roughly 85% of the bone
compact or cortical bone
What makes up the cortical bone
Haversian system
What is the functional unit of the Haversian system
Osteon
what is the lamellae
Central or Haversian canal surrounded by layers of matrix
What does the lamellae contain
Arterial / venous blood supply, nerves, lymph
What are lacunae
spaces between lamellae layers
Where are osteocytes found
in the lacunae
Why are osteocytes within the lacunae covered in fluid
To allow for transfer of nutrients and waste
what are canaliculi
Extensions of the osteocyte that allow for nutritional exchange
Where is the volkman canal
Perpendicular to the Haversian canal and contain the vasculature
Which part of the bone is layered, mesh like formation of trabeculae
Spongy bone
What covers the spongy bone
Endosteum
What is the role of the spongy bone
Assist with metabolic demands of the bone
What cells does the endosteum contain
osteoblasts and precursor cells
Where is the endosteum found
Lining the inner aspect the bone covering the trabeculae
lines the canals weaving through cortical bone
Where is bone marrow found
within the medullary canal and within the spongy bone
What is red marrow responsible for
hematopoiesis
What is yellow marrow responsible for
storing fat unless trauma occurs-> then can turn into red marrow
What does the boney matrix contain
Calcium binding proteins, adhesion proteins, mineralization proteins (osteocalcin)
What is the most important building block in the body
Collagen
What makes up the bone matrix
osteoid and minerals
What does crystalize calcium do in the boney matrix
Hard support for the bone
What do collagen fibers do in the bone matrix
support/strength
What do proteoglycans do
Proteins that transport calcium and help organize the extracellular matrix
What do bone morphogenic proteins do
assist with repair of bone and supportive structures
What do osteoblasts secrete
Collagen
What is the order of bone formation in fetal development
chondrocytes
osteoblasts
osteocytes
What allows for mineralization of the bone
Calcium phosphate -> hydroxyapatite crystal
How does PTH effect osteoblasts
A change in PTH will cause a release of osteocalcin which creates an osteoid
What is an osteoid
non-mineralized bone
What determines the rate of osteoclast formation
RANKL cells which are controlled by hormones and nutrition
What is the progression of bone cells in the body
mesenchymal stem cells
osteoprogenetor cells
osteoblasts
osteocyte
What do osteoblasts produce
calcium phosphate which is then converted in hydroxyapatite and collagen
What does transforming growth factor do
protein that regulates bone formation
What stimulates bone growth
Pressure
What occurs when calcium blood levels increase
Thyroid gland will secrete calcitonin which then stimulates calcium deposits in the bone
What occurs when calcium blood levels decrease
Parathyroid gland releases PTH which causes osteoclasts to degrade bone matrix and release calcium into the blood
What makes up the majority of bone cells
Osteocyte
Where are osteocytes found
Encased in osteoid within the space of lacuna
What is the purpose of cilia on osteocytes
To act as mechanoreceptors
What is the role of osteocytes
Control calcium and phosphate levels
Tell osteoclasts and osteoblasts when to alter bone formation
endocrine receptor
What is the osteoclast
macrophage of the bone
How do osteoclasts break down bone
triggers PTH secretion
Hydrochloric acid will dissolve mineral in the bone
Create resorption lacunae which is irregular surface
What happens when osteoclasts are stimulated by calcitonin
Release their podosomes
Where does calcitonin come from and what is its role
Thyroid gland
Lowers calcium blood levels
What does the parathyroid hormone do and where does it come from
Parathyroid glands
increases blood calcium levels
What are the key hormones in bone development
Calcitonin
parathyroid
vitamin D synergist of PTH
How are long bones developed
Via enchondral ossification from hyaline cartilage
What area of bone allows for elongation
metaphysis
What is positional bone growth
thickening of the bone
