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Questions and Answers
What is the primary function of osteoclasts in bone physiology?
What is the primary function of osteoclasts in bone physiology?
Which of the following is NOT a function of bone?
Which of the following is NOT a function of bone?
What advantage does trabecular bone have over compact bone?
What advantage does trabecular bone have over compact bone?
What role does synovial fluid play in joint function?
What role does synovial fluid play in joint function?
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Which part of the body contains ossicles that contribute to sound transmission?
Which part of the body contains ossicles that contribute to sound transmission?
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What happens to bone strength when osteocytes die due to poor blood supply?
What happens to bone strength when osteocytes die due to poor blood supply?
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Which of the following elements is primarily stored in bones for the body's use?
Which of the following elements is primarily stored in bones for the body's use?
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Which of the following statements about bone remodeling is true?
Which of the following statements about bone remodeling is true?
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What property of trabecular bone allows it to absorb more energy compared to compact bone?
What property of trabecular bone allows it to absorb more energy compared to compact bone?
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At what stress level does bone typically break, according to the provided information?
At what stress level does bone typically break, according to the provided information?
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According to Hooke's law, how does strain change in relation to stress at the beginning of deformation?
According to Hooke's law, how does strain change in relation to stress at the beginning of deformation?
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What is the significance of Young's modulus in the context of bone mechanics?
What is the significance of Young's modulus in the context of bone mechanics?
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Which type of fracture is indicated by a spiral fracture in the tibia?
Which type of fracture is indicated by a spiral fracture in the tibia?
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What phenomenon has been suggested to play a role in bone growth and repair?
What phenomenon has been suggested to play a role in bone growth and repair?
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What is the calculated amount of shortening in a leg bone when supporting a body weight of 700 N?
What is the calculated amount of shortening in a leg bone when supporting a body weight of 700 N?
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When a bone is subjected to bending stresses, where do these stresses primarily occur?
When a bone is subjected to bending stresses, where do these stresses primarily occur?
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What is the primary organic component of bone that contributes to its flexibility?
What is the primary organic component of bone that contributes to its flexibility?
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Which statement correctly describes the difference between compact bone and trabecular bone?
Which statement correctly describes the difference between compact bone and trabecular bone?
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How can bone mineral be described based on its composition?
How can bone mineral be described based on its composition?
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What does the large surface area of bone mineral crystals facilitate?
What does the large surface area of bone mineral crystals facilitate?
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What is the result when collagen is removed from a bone?
What is the result when collagen is removed from a bone?
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What happens to bone structure when a bone tumor is present?
What happens to bone structure when a bone tumor is present?
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Which chemical element is used to identify bone tumors not yet visible on x-rays?
Which chemical element is used to identify bone tumors not yet visible on x-rays?
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In what way is trabecular bone advantageous compared to compact bone?
In what way is trabecular bone advantageous compared to compact bone?
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What is the primary consequence of rheumatoid arthritis on joint structure?
What is the primary consequence of rheumatoid arthritis on joint structure?
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How does the viscosity of synovial fluid change under stress?
How does the viscosity of synovial fluid change under stress?
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Which substances contribute to the lubricating properties of synovial fluid?
Which substances contribute to the lubricating properties of synovial fluid?
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What is a key feature of articular cartilage?
What is a key feature of articular cartilage?
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What role does the porous nature of articular cartilage play in joint lubrication?
What role does the porous nature of articular cartilage play in joint lubrication?
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What is the relationship between bone mineral mass and osteoporosis?
What is the relationship between bone mineral mass and osteoporosis?
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Why is a precise technique needed to measure bone mineral mass?
Why is a precise technique needed to measure bone mineral mass?
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What does the coefficient of friction in a joint relate to?
What does the coefficient of friction in a joint relate to?
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What is a major drawback of using traditional x-rays for measuring bone mineral density?
What is a major drawback of using traditional x-rays for measuring bone mineral density?
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Which component is NOT part of the improved photon absorptiometry technique?
Which component is NOT part of the improved photon absorptiometry technique?
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In the formula $BM (g/cm^2) = K log (I_0/I)$, what does $K$ represent?
In the formula $BM (g/cm^2) = K log (I_0/I)$, what does $K$ represent?
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How does the in vivo activation technique measure calcium in the body?
How does the in vivo activation technique measure calcium in the body?
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What is one of the key improvements made in photon absorptiometry over traditional x-ray techniques?
What is one of the key improvements made in photon absorptiometry over traditional x-ray techniques?
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Which source of radiation is specifically mentioned as suitable for photon absorptiometry?
Which source of radiation is specifically mentioned as suitable for photon absorptiometry?
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What problem does a narrow beam solve in the context of photon absorptiometry?
What problem does a narrow beam solve in the context of photon absorptiometry?
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What characteristic of conventional x-ray techniques makes them less effective for quantitative measurements?
What characteristic of conventional x-ray techniques makes them less effective for quantitative measurements?
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Study Notes
Physics of Skeleton
- The skeletal system is of interest to medical physicists and engineers due to the complex static and dynamic forces encountered during various bodily functions.
- Bone has at least six key functions: support, locomotion, protection of organs, storage of chemical elements, nourishment, and sound transmission.
- Bones are composed primarily of calcium hydroxyapatite, which absorbs x-rays more effectively than surrounding soft tissue. This is why bones are easily visible on x-rays.
- Bone is also composed of collagen, the organic component.
- Trabecular bone, with its thin thread-like structure, is found in the ends of long bones, and is weaker than compact bone, but better at absorbing shock and impact.
- Compact bone is primarily in the central shaft of long bones, providing strength and support essential for forces in walking, running, and jumping.
- Bone is a living tissue that undergoes constant remodeling, with specialized cells (osteoclasts) removing old bone and (osteoblasts) building new bone.
- Synovial fluid lubricates the joints, preventing friction and wear and tear.
- Diseases like rheumatoid arthritis can cause overproduction of synovial fluid, leading to swollen joints.
- Problems like difficulties in x-ray measurement of bone mineral mass include heterogeneous beam energies, much scattered radiation, and poor film detector properties.
- An improved technique, photon absorptiometry, was developed, using gamma sources and scintillation detectors to overcome limitations of conventional x-rays.
- A radioisotope, like iodine 25 or americium 241, can be used as a radiation source in vivo activation to measure bone mineral mass.
Bone Strength and Fracture
- Bone strength depends on the amount of bone mineral present.
- Osteoporosis is characterized by low bone mineral mass, increasing the risk for fractures.
- Bones can withstand a significant amount of tension before fracturing.
- Fractures commonly occur due to shear or tension forces rather than compression.
- The body repairs bone fractures relatively quickly if the region is immobilized.
Measurement of Bone Mineral
- Methods for measuring bone mineral mass in vivo include x-ray techniques and in-vivo activation.
- X-ray imaging techniques have limitations, such as having a heterogeneous beam, significant scatter, and a poor film detector.
- In-vivo activation uses energetic neutrons to convert calcium into radioactive forms, which emit gamma rays used in bone mineral mass assessments.
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