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5 functions of bones
-support
-protection
-movement
-mineral storage
-blood cell formation
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description of compact bone? (2)
-smooth
-continuous solid
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description of spongy bone? (2)
-narrow
-irregular bars
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2 parts of long bone
-diaphysis
-epiphysis
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2 parts of long bone- description of diaphysis
-shaft
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2 parts of long bone- what 2 things make up diaphysis made off?
-compact bone
-medullary cavity
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2 parts of long bone- description of epiphysis
-bulbous end of bones
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2 parts of long bone- Epiphysis- What does epiphysis contain?
- -articular cartilage
- *hyaline
- -epiphyseal line
- *old growth plate
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which are the 2 membranes in long bone?
-periosteum
-endosteum
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2 membranes in long bone- where is the Periosteum located?
it is the outside covering
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2 membranes in long bone- Where is the endosteum located?
- inside lining
- *medullary cavity and spongy bone
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2 membranes in long bone- what types of cells do periosteum and endosteum contain?
osteogenic cells
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how is the compact bone and spongy bone positioned in short, irregular, and flat bones?
compact bone sandwiching spongy bone
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In flat bones, what is the spongy bone called?
diploë
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Do short, irregular, and flat bones contain perisoteum and endosteum?
yes
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What is the function of hematopoietic tissue?
tissues that develops blood
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hematopoietic tissues- What is the function of rd marrow?
areas where blood formation occurs
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hematopoietic tissues- In adults where is red marrow foiund? (2)
-generally within the trabecular cavities of select long bones
-diploë of flat bones
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hematopoietic tissues- why is the medullary cavity called yellow marrow in adulthood?
- this area turns into fat
- *in infants, this cavity contains red marrow
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histology of compact bone- what is an osteon? (2)
-they are structural unit of compact bone
-cylinders of bone
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histology of compact bone- What are lamellae?
they care concentric layers that form osteon
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histology of compact bone- What are haversion canals?
- central canal of osteons
- *these are filled with blood vessels that supply nutrients to bones even at the deepest portions
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histology of compact bone- what are volkmann canal?
- transverse canals
- *runs laterally from haversion canals
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histology of compact bone- What are osteocytes?
mature bone cells
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histology of compact bone- what are lacunae?
cavities containing osteocytes
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histology of compact bone- What are canaliculi?
connect lacunae and haversion canals
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histology of compact bone- what are interstitial lamellae?
they are found between osteons
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histology of compact bone- what are circumferential lamallae?
these encircle the whole bone
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histology of spongy bone- where are trabaculae arranged?
- they align along lines of stress
- *if arm gets alot of stress then they will form more on the arm
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microscopic chemical composition of bone- cells- What are osteogenic cells?
stem cells
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microscopic chemical composition of bone- cells- what are osteoblast cells? (2)
-synthesizes matrix
-cells responsible for bone growth
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microscopic chemical composition of bone- cells- What are osteocytes? (2)
-mature bone cells
-maintain the bone matrix
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microscopic chemical composition of bone- cells- What are osteoclast?
- -bone resorbing cell
- *destroys bones
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microscopic chemical composition of bone- cells- do osteoclast derive from same stem cell as the other 3 cells?
no, it derives from WBC
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Matrix- Ground substance- What is the ground substance made up off?
- osteoid
- *this is secreted by osteoblasts
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Matrix- Ground substance- What 3 things can make up ground subtance?
-proteoglycans
-glycoproteins
-hydrocyapatites
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Matrix- Ground substance- What are proteglycans?
large protein and CHO
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Matrix- Ground substance- what are glycoproteins?
smaller protein and CHO
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Matrix- Ground substance- What are hydroxyapatites?
- calcium phosphates
- *this comes out when matrix is broken down
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Matrix- fiber- what type of fibers are in bones?
- collagen
- *low water content compared to cartilage
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What is the function of having compact bone periphery and spongy bone central?
strong but light weight
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What is the function of having calcium phosphates?
calcium and phosphate stores
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What is the function of having osteoclasts and blast and osteogenic cells? (2)
-clasts break down bone for relaease of minearals
-blasts build bone
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What is the function of having marrow cavity?
space for blood cell development
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what is osteogenesis?
formation of bone
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what is the precursor of intramembranous ossification?
an embryonic connective tissue called mesenchyme
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intramembraneous ossification- 4 steps of this process
-initial ossification center
-secretion and calcification of osteoid
-formation of woven bone
-lamellar bone replaces woven bone
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intramembraneous ossification- where can this type of ossification be found in?
flat bones
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where does endochondral ossification occur?
long bones
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endochondral ossification- what is the precursor tissue?
cartilage
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endochondral ossification- 5 steps- what happens in step 1
osteoblasts form bone collar around the cartilage
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endochondral ossification- 5 steps- what happens in step 2? (2)
-central cartilage calcifies
-cavities develop
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endochondral ossification- 5 steps- What happens in step 3?
- -periosteal bud invades
- *artery, vein, and nerve fibers
- **these bring osteoclasts
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endochondral ossification- 5 steps- what happens in step 4? (3)
-bone grow longer
-medullary cavity forms
-2ndary ossification begins at epiphyseal regions
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endochondral ossification- 5 steps- What happens in step 5?
-epiphyses ossify leaving cartilage within epiphyseal plate and at articular surfaces of bone
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long bone growth- how does it grow in length?
cartilage growth followed by replacement of cartilage by bone
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long bone growth- does the cartilage grow on distal end of epiphysis and/or epiphyseal plate?
both sides
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long bone growth- what happens to the cartilage at epiphyseal plate?
- it is replaced by bone
- *osteoblasts multiply and secrete matrix on shaft side of epiphyseal plate
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long bone growth-what follows osteoblasts to carve out medullary cavity?
osteoclasts
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long bone growth- what happens to the epiphyseal plate once growth is finsihed?
it turns into epiphyseal line
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long bone growth- after growth is finshed, where does the cartilage appear?
- on the distal end of epiphysis
- *where bones have articular surfaces
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appositional- how does the bone grow thicker?
periosteal osteoblast lays down bone and secretes matrix
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regulations of bone functions- what 3 hormones regulate growth?
-growth hormone
-thyroid hormone
-androgenic and estrogenic steroids
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regulations of bone functions-growth hormone- where is GH released from and what causes the liver to release?
-anterior pituatary
-causes liver to release somatomedins
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regulations of bone functions-GH- what does somatomedins do?
initiates cartilage growth at epiphyseal plate
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regulations of bone functions- what does androgenic and estrogenic steroids do?
epiphyseal plate closure
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remodeling- what are groups of osteoblasts and osteoclasts called?
remodeling units
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remodeling- What do remodeling units do?
continuously synthesize and remove bone
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remodeling- What are the areas of new deposit referred as? and how long does it calcify?
-osteoid seam and it take about a week to calcify
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remodeling- in areas of resorption, what do osteoclasts do?
dig depressions to break down matrix
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remodeling- why do osteoclasts disgest material?
the material will then become soluble and can be relased into bloodstream
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remodeling- What do osteoclasts remove?
dead osteocytes
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remodeling-hormones- What does the parathyroid hormone do?
increases osteoclast activity
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remodeling-hormones- when are the parathyroid hormone released?
when calcium level is low
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remodeling-hormones- what are calcitonin?
they inhibit osteoclasts
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response to mechanical stress- What is wolff's law?
- bone grows and remodels in response to mechanical demand
- *muscle pull and load
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response to mechanical stress- 4 things that attirubte to wolffs law?
-asymmetrical limb thickness
- -increased thickness at curved areas
- *most likely to buckle under tension
- -spongy bone trusses along lines of compression
- *to strengthen the central part of bone
- -enhanced bony projections at muscle attachments
- *they are built that way to withstand stress
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