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True or false: Bone is not a type of connective tissue.
false.
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Osteogenic cells
- a bone stem cell
- the precursor to all the other cell types
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What are osteoblasts?
they are dividing cellsthey are responsible for laying down the components of bonewe can disstinguish them from other cells which all start with "osteo-" by remembering that they are bone building blasts.
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What is the funciton of osteocytes?
they maintain bone integrity within spaces inside of bone
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Osteoclasts
- Bone-chewing
- constsnly tunnel through bone, dissolving the bone matrix as they go.
- They are followed by osteoblasts
- in this way bone is constantly renewed and can sytrengthen when needed.
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Both _________ and _________ play an important role in keeping blood ________ and phosphorus within normal limits so they are controlled by _________.
osteoblasts, osteoclasts, calcium, hormones
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What are the four cell types found in bone?
- osteogenic cell: precursor to other cell types
- Osteoblast: forms bone (bone building osteoblasts)
- osteocyte: maintains bone tissue
- osteoclast: break down bone (bone chewing osteoclast)
- osteoblasts and osteoclasts are regulated by hormones
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What are the two components of bone?
inorganic and organic
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Hydroxapatite
- The ionorganic portion of bone
- a compound of calcium, phosphate and hydroxyl groups
- its chemicla formula is : Ca10(PO4)6(OH)2
- This forms the rigid, brittle inorganic matrix of bone.
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Bone also has an organic matrix, made up of mostly _______ ____ __.
collagen type I
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Bone is natures _________ material. Just like the skin of amodern jet fightyer is composite material of metal and non-metal, ______ depends on the proper mixture of _______ and ________ components.
composite, inorganic, organic
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True or False: If bones have to little mineral, it becomes brittle and fractures easily.
False. If bones have to much mineral, it becomes brittle and fractures easily.- This happens in the disease osteogenesis imperfecta, or "brittle bone disease".
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What causes children with rickets and adults with osteomalacia to have soft and pliable bones?
If the bones have to much collagen
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Why is it nessesary to have both mineral (inorganic) and collagen (organic) components working together?
- Mineral alone is to brittle
- -Osteogenesis imperfecta
- Organic alone is to flexible
- -rickets or osteomalacia
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Module 9
Graphic objective 3. Compare and contrast compact and spongy bone.
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If blood _________ is low, the body breaks down ________ _______ to release calcium into the bloodstream. If blood calcium is high, the body stores ______ in ______for future needs.
calcium, mineralized bone, calcium, bone
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True or False: A balance between osteoblasts and osteoclasts is critical, and is under hormonal control.
True.
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If you have low blood calcium...
- the body withraws calcium from its calcium "bank": bone tissue
- Parathyroid hormone is released from a set of small pea-shaped glands next to the thyroid
- this increased osteoclasts activity
- Osteoclasts break down the mineral portion of bone and calcium is released into the bloodstream.
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If blood calcium is too high...
- Calcitonin is made by parafolicular cells (C cells) in the thyroid gland
- -it is released when calcium is high and stimulates osteoblasts
- Theses absorb calcium form the bloodstream and dposit it as hydroxyapatite in bone.
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What are the three hormones involved in hormonal control of the blood?
- 1. Calcitonin
- 2. Parathytroif hormone (PTH)
- 3. Calcitriol
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Calcitonin
- inhibirs osteoclasts
- stimulates osteoblasts
- decreases blood calcium
- increases bone formation
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Parathyroid hormone (PTH)
- stimulates osteoclasts
- inhibits osteoblasts
- increase blood calcium
- decrease bone formation
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Calcitriol
- not directly invoved with bone however,
- PTH stimulates kidneys to release calcitriol, which increases absorption of calciumfrom food
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There are two D vitamins. Vitamin D2 (___________) and vitamin D3 (___________) are made in the skin with the help of UV-B light (i.e. ______ _______).
ergocalciferol, cholecalciferol, natural sunlight
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True or false: Vitamin D is importand in the intestinal absoption of calcium.
true.
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In the absences vitamin D...
- blood calcium levels drop and bones become soft and flexible (bones are nostly colagen because mineral portion is lacking)
- In children this results in rickets
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Osteomalacia
- In adults, inability to form mineralized bone
- May result from metabolic disturbances, cancer, or cancer chemotherapy
- Scan shows radioactiv 99Tc concentrating in areas that are making organic bone matrix but not the inorganic materialized porttionof bone.
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