Bone & Joint
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- What are the 5 functions of bone?
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1. protection
2. mineral storage
3. movement
4. support and shape
5. hematopoiesis - Of the composition of bone, what % of its mass is composed of cells?
- 5-8% of its mass are cells, th remaining 92-95% is extracellular matrix.
- Of the extracellular matrix, what percent is made up of Organic matter?
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35% is organic matter (osteoid)
90-95% of the organic matter is Type I collagen - Of the extracellular matrix, what percent is made up of Inorganic Matrix?
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65% is inorganic matrix
70% of the inorganic matter is Hydroxyapatite - What are the four macroscopic components of a bone?
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1. Cortical bone
2. trabecular bone
3. periosteum
4. endosteum - What are the characteristics of cortical bone?
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- Lemellar collagen fibers
- dense and strong
- outer covering supports and protects bone - What are the characteristics of trabecular bone?
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- lamellar and woven
- found in bone medullary cavity, skull, vertebral bodies - What are the characteristics/functions of periosteum?
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- The outer fibrous and vascular layer of bone
- Inner cambium layer contains osteoblasts and osteoclasts
- functions in growth, repair and nutrition of bone - Where is the endosteum?
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It lines the inner margin of the cortex and trabeculae.
- It also contains osteoblasts and osteoclasts - What are the four divisions of bone?
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1. Epiphysis
2. Physis
3. Metaphysis
4. Diaphysis - What are the four types of cells in bone?
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1. Osteoprogenitor cells (becomes fibroblasts, chondroblasts, or osteoblasts)
2. Osteoblasts
3. Osteocytes
4. Osteoclasts - What enzyme is contained in the cytoplasm of osteoblasts?
- Alkaline Phosphatase
- If a Dr. wanted to determine if there was a broken bone, what would be the purpose of doing a blood test?
- The Dr. would be checking for alkaline phosphatase in the blood, as it is an indicator of osteoblastic activity and possible broken bone or tumor in the bone.
- Which cell within bone mediates Wolff's Law?
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Osteocytes
They regulate the cell environment - Within bone, where are osteocytes located?
- Within the canniliculi. They transport fluid through the canniliculi.
- Which cells within bone are multinucleated?
- Osteoclasts
- Where do osteoclasts reside within bone?
- Howship's lacunae
- Hyperemia in bone leads to what?
- Increased osteoclastic activity, resulting in osteoporosis
- Ischemia in bone leads to what?
- Increased osteoblastic activity, resulting in bone sclerosis
- When does ossification begin (what weeks?) in the fetus?
- 6th, 7th, and 8th weeks
- Describe intramembranous bone formation
- bones form directly from osteoblasts that are clustered within a fibrous membrane. There is no pre-existing cartilage model.
- Where does intramembranous bone formation predominate during fetal growth development?
- In the skull and facial bones, as flexibility is needed.
- Describe endochondral bone formation
- A pre-existing cartilage model calcifies and is replaced by bone.