Skeleton and Movement
Short Questions
1. What is the functional unit of striated muscle?
Answer: The sarcomere is the functional unit of striated muscle.
2. Which bones are involved in an ankle fracture?
Answer: Tarsal bones are involved in an ankle fracture.
3. What causes muscle fatigue?
Answer: Accumulation of lactic acid causes muscle fatigue.
4. Which muscle pair is not antagonistic?
Answer: Sphincters and supinators are not an antagonistic pair.
5. How does soaking a sprained foot in salty water reduce swelling?
Answer: Osmosis draws water out of the swollen tissue, reducing swelling.
6. What is the role of calcium in muscle contraction?
Answer: Calcium binds to troponin, exposing actin’s binding sites for myosin.
7. Which disorder is caused by hyper-secretion of parathormone?
Answer: Osteoporosis is caused by hyper-secretion of parathormone.
8. What type of contraction occurs in neck muscles while reading?
Answer: Isometric contraction occurs in neck muscles while reading.
9. Which joint moves during bicep training with dumbbells?
Answer: The elbow joint moves during bicep training with dumbbells.
10. Why is a splint essential for a fractured leg?
Answer: A splint immobilizes the fracture, preventing further damage and pain.
11. Why is a sprain more painful than a fracture?
Answer: Sprains involve nerve-rich ligaments, causing intense pain and inflammation.
12. Why do red muscle fibers work longer than white fibers?
Answer: Red fibers use aerobic respiration, resisting fatigue longer than white fibers.
13. What is the total number of bones in the human skeleton?
Answer: The human skeleton has 206 bones.
14. What type of joint is the elbow?
Answer: The elbow is a hinge joint, allowing flexion and extension.
15. What is rigor mortis?
Answer: Rigor mortis is post-death muscle stiffening due to ATP depletion.
Long Questions
1. How does the sarcomere’s structure facilitate muscle contraction?
Answer: The sarcomere contains actin and myosin filaments arranged for sliding. Calcium triggers tropomyosin movement, exposing actin’s binding sites. Myosin heads pull actin, shortening the sarcomere via the sliding filament theory.
2. Why did Ragini, a 50-year-old, suffer hairline cracks in her feet?
Answer: Ragini likely has osteoporosis due to postmenopausal estrogen decline. Low calcium and vitamin D intake weakened her bones. She should take calcium supplements and exercise to prevent further fractures.
3. How do actin and myosin structures contribute to muscle contraction?
Answer: Actin’s tropomyosin and troponin regulate myosin binding when calcium is present. Myosin’s heads, with ATPase activity, form cross-bridges with actin. These bridges pull actin, causing sarcomere shortening and contraction.
4. Why are the atlas and axis vertebrae structured differently?
Answer: The atlas is ring-like, supporting the skull and enabling nodding. The axis’s odontoid process forms a pivot joint for rotation. Their structures suit their roles in head movement and spinal cord protection.
5. Why is a wooden splint used for a fractured leg in emergencies?
Answer: A splint stabilizes the fractured leg, preventing bone movement. This reduces pain and further tissue damage during transport. It ensures safe handling until medical treatment is provided.
6. Why are sprains often more painful than fractures?
Answer: Sprains damage ligaments, which are richly innervated, causing severe pain. Fractures may be less painful if the break is clean. Swelling and inflammation in sprains further intensify discomfort.
7. How do red and white muscle fibers differ in function?
Answer: Red fibers, rich in myoglobin and mitochondria, support prolonged aerobic activity. White fibers, relying on anaerobic glycolysis, fatigue quickly due to lactic acid buildup. This suits red fibers for endurance and white for short bursts.
8. What is the role of calcium in muscle contraction and relaxation?
Answer: Calcium binds to troponin, exposing actin’s binding sites for contraction. During relaxation, calcium is pumped back into the sarcoplasmic reticulum. This restores tropomyosin’s position, preventing myosin-actin interaction.
9. How do synovial joints enable free movement?
Answer: Synovial joints have a synovial cavity filled with lubricating fluid. Hyaline cartilage reduces friction, and ligaments prevent dislocation. This structure allows multiaxial or monoaxial movements, like in the hip or elbow.
10. What is osteoporosis, and how can it be prevented?
Answer: Osteoporosis is a condition where bones become brittle due to excessive resorption. It can be prevented with a calcium-rich diet and weight-bearing exercises. Regular bone density screenings help monitor and manage risk.
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