Skeletal System: 66 flashcards
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1. What is ossification?
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The process of bone formation, where cartilage or fibrous tissue is replaced by bone.
2. What are the two main types of ossification?
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Intramembranous ossification and endochondral ossification.
3. Which type of ossification forms flat bones like the skull?
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Intramembranous ossification.
4. Which type of ossification forms long bones like the femur?
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Endochondral ossification.
5. What is the primary ossification center?
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The first area where bone begins to form in a developing bone, typically in the diaphysis (shaft) of long bones.
6. What is the secondary ossification center?
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Areas of bone formation that appear later, usually in the epiphyses (ends) of long bones.
7. What is the epiphyseal plate?
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A layer of hyaline cartilage at the junction of the epiphysis and diaphysis where bone growth in length occurs.
8. What happens to the epiphyseal plate when bone growth stops?
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It ossifies and becomes the epiphyseal line.
9. What is appositional growth?
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Growth in bone width by adding new bone tissue to the outer surface by osteoblasts.
10. Which cells build new bone?
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Osteoblasts.
11. Which cells break down bone?
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Osteoclasts.
12. What are osteocytes?
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Mature bone cells that maintain bone tissue.
13. What is the role of osteoblasts in bone development?
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They synthesize and secrete collagen fibers and other organic components of bone matrix, and initiate calcification.
14. What is the role of osteoclasts in bone development?
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They resorb bone tissue, which is important for remodeling and growth.
15. What is bone remodeling?
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The ongoing process of bone resorption by osteoclasts and bone formation by osteoblasts to maintain bone strength and regulate calcium.
16. How does a long bone grow in length?
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By interstitial growth at the epiphyseal plate: cartilage cells proliferate and then ossify, pushing the epiphysis away from the diaphysis.
17. How does a bone grow in width?
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By appositional growth: osteoblasts add new bone to the outer surface, while osteoclasts remove bone from the inner surface.
18. What is the diaphysis?
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The shaft or central part of a long bone.
19. What is the epiphysis?
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The end part of a long bone, initially growing separately from the shaft.
20. What is the medullary cavity?
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The central cavity of the diaphysis that contains bone marrow.
21. What is the periosteum?
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A dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.
22. What is the endosteum?
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A thin vascular membrane of connective tissue that lines the inner surface of the bony tissue that forms the medullary cavity.
23. What is the role of cartilage in endochondral ossification?
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Cartilage serves as a template that is gradually replaced by bone.
24. What is the first step of intramembranous ossification?
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Mesenchymal cells cluster and differentiate into osteoblasts.
25. What is the first step of endochondral ossification?
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A cartilage model of the bone is formed by chondrocytes.
26. What is the role of blood vessels in bone development?
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They bring nutrients and oxygen, and deliver osteoblasts and osteoclasts to the site of ossification.
27. What is the significance of the epiphyseal plate in forensic age estimation?
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The presence and width of the epiphyseal plate can indicate the age of a growing individual, as it closes at different times for different bones.
28. What is the mnemonic to remember the order of bone cells?
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Osteogenic → Osteoblast → Osteocyte → Osteoclast (GOBC: Go Build Cells).
29. What is the mnemonic to remember the types of ossification?
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Intramembranous = 'In Membrane' (flat bones); Endochondral = 'Inside Cartilage' (long bones).
30. What is the story to remember bone growth in length?
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Imagine a growing tree: the epiphyseal plate is like the cambium layer that adds new wood (bone) each year, pushing the ends (epiphyses) apart.
31. What is the story to remember bone remodeling?
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Think of a construction site: osteoblasts are the builders laying bricks (bone), osteoclasts are the demolition crew removing old bricks, and osteocytes are the supervisors maintaining the structure.
32. What is the mnemonic to remember the zones of the epiphyseal plate?
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Resting → Proliferative → Hypertrophic → Calcified (RPHC: Really Pretty Hyaline Cartilage).
33. What is the resting zone of the epiphyseal plate?
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A region of small, inactive cartilage cells near the epiphysis.
34. What is the proliferative zone of the epiphyseal plate?
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A region where cartilage cells divide rapidly and line up in columns.
35. What is the hypertrophic zone of the epiphyseal plate?
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A region where cartilage cells enlarge and the matrix begins to calcify.
36. What is the calcified zone of the epiphyseal plate?
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A region where cartilage cells die and the matrix becomes calcified, then replaced by bone.
37. What is the role of vitamin D in bone development?
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It helps in the absorption of calcium and phosphorus from the intestine, which are essential for bone mineralization.
38. What is the role of vitamin C in bone development?
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It is required for collagen synthesis, which is a major component of bone matrix.
39. What is the role of calcium in bone development?
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Calcium is a major mineral component of bone, providing strength and rigidity.
40. What is the role of phosphorus in bone development?
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Phosphorus combines with calcium to form hydroxyapatite, the mineral crystals that harden bone.
41. What is hydroxyapatite?
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A mineral form of calcium apatite, which is the main inorganic component of bone and teeth.
42. What is the effect of growth hormone on bone development?
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It stimulates growth at the epiphyseal plate and increases bone length.
43. What is the effect of sex hormones on bone development?
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They promote bone growth and eventually cause closure of the epiphyseal plate, stopping growth in length.
44. What is achondroplasia?
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A genetic disorder that affects bone growth, particularly in long bones, resulting in dwarfism.
45. What is osteoporosis?
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A condition where bone resorption exceeds bone formation, leading to weak and brittle bones.
46. What is the difference between osteoblasts and osteoclasts?
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Osteoblasts build bone, while osteoclasts break down bone.
47. What is the difference between intramembranous and endochondral ossification?
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Intramembranous ossification forms bone directly from mesenchymal tissue, while endochondral ossification forms bone by replacing a cartilage model.
48. What is the role of the periosteum in bone growth?
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It contains osteogenic cells that differentiate into osteoblasts, contributing to appositional growth.
49. What is the role of the endosteum in bone growth?
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It contains osteoclasts that resorb bone, helping to shape the medullary cavity.
50. What is the mnemonic to remember the functions of bone?
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Support, Protection, Movement, Mineral storage, Blood cell production (SPMMB: Some People Make Many Bones).
51. What is the story to remember the process of endochondral ossification?
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Imagine a cartilage model as a soft clay figure. Osteoblasts are sculptors who gradually replace the clay with stone (bone), starting from the center (primary ossification center) and later at the ends (secondary ossification centers).
52. What is the mnemonic to remember the cells involved in bone remodeling?
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Osteoblasts Build, Osteoclasts Crash, Osteocytes Maintain (BBC: Build, Break, Care).
53. What is the role of osteocytes in bone?
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They maintain bone tissue and communicate with osteoblasts and osteoclasts to regulate bone remodeling.
54. What is the role of osteogenic cells?
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They are stem cells that differentiate into osteoblasts and are found in the periosteum and endosteum.
55. What is the significance of the medullary cavity in bone development?
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It houses bone marrow, which produces blood cells, and its formation is part of bone remodeling.
56. What is the effect of mechanical stress on bone development?
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Mechanical stress stimulates bone remodeling, increasing bone density and strength in areas of high stress.
57. What is the role of parathyroid hormone (PTH) in bone development?
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PTH stimulates osteoclasts to release calcium from bone into the blood, increasing blood calcium levels.
58. What is the role of calcitonin in bone development?
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Calcitonin inhibits osteoclasts and stimulates osteoblasts, decreasing blood calcium levels and promoting bone formation.
59. What is the mnemonic to remember the hormones affecting bone?
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PTH raises calcium (Put The calcium High), Calcitonin lowers calcium (Calcitonin Tones down calcium).
60. What is the story to remember the role of vitamins in bone development?
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Imagine vitamin D as a key that unlocks calcium absorption, vitamin C as a glue for collagen, and vitamin A as a coordinator for bone growth.
61. What is the difference between bone growth in length and bone growth in width?
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Growth in length occurs at the epiphyseal plate by interstitial growth, while growth in width occurs by appositional growth at the periosteum.
62. What is the role of chondrocytes in endochondral ossification?
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Chondrocytes form the cartilage model and later undergo hypertrophy and calcification, providing a template for bone formation.
63. What is the fate of the epiphyseal plate after growth?
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It ossifies and becomes the epiphyseal line, marking the end of longitudinal growth.
64. What is the mnemonic to remember the layers of bone?
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Periosteum, Compact bone, Spongy bone, Endosteum (PCSE: Please Come See Endosteum).
65. What is the role of the epiphyseal plate in bone growth?
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It is the site of longitudinal bone growth, where cartilage is continually produced and replaced by bone.
66. What is the story to remember the zones of the epiphyseal plate?
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Imagine a factory assembly line: resting zone (storage), proliferative zone (workers multiplying), hypertrophic zone (workers growing), calcified zone (workers turning into product).
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