Nursing practice questions with comprehensive rationales
NurseDive Free Nursing Practice Question
The protein that acts as a calcium receptor in skeletal muscle is:
A. Actin
Actin is a structural protein that forms the thin filaments in muscle fibers. While it interacts with myosin during contraction, it does not bind calcium directly.
B. Tropomyosin
Tropomyosin is a regulatory protein that blocks the myosin-binding sites on actin in a resting muscle. It shifts position when calcium binds to troponin but does not itself bind calcium.
C. Titin
Titin is a large elastic protein that helps maintain the structural integrity of the sarcomere and contributes to passive elasticity. It does not function as a calcium receptor.
D. Troponin
Troponin is the correct answer. It is a regulatory protein complex associated with the thin filament. When calcium ions bind to troponin, it induces a conformational change that moves tropomyosin away from actin’s binding sites, allowing muscle contraction to occur.
E. Dystrophin
Dystrophin is a structural protein that connects the cytoskeleton of muscle fibers to the extracellular matrix. It is important for muscle integrity but does not bind calcium.
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Full Explanation
Choice A reason: Actin is a structural protein that forms the thin filaments in muscle fibers. While it interacts with myosin during contraction, it does not bind calcium directly.
Choice B reason: Tropomyosin is a regulatory protein that blocks the myosin-binding sites on actin in a resting muscle. It shifts position when calcium binds to troponin but does not itself bind calcium.
Choice C reason: Titin is a large elastic protein that helps maintain the structural integrity of the sarcomere and contributes to passive elasticity. It does not function as a calcium receptor.
Choice D reason: Troponin is the correct answer. It is a regulatory protein complex associated with the thin filament. When calcium ions bind to troponin, it induces a conformational change that moves tropomyosin away from actin’s binding sites, allowing muscle contraction to occur.
Choice E reason: Dystrophin is a structural protein that connects the cytoskeleton of muscle fibers to the extracellular matrix. It is important for muscle integrity but does not bind calcium.
Similar Questions
Opposition is the movement of any bone in the body that opposes another bone in the body.
A. True
Opposition is a specific movement that occurs primarily in the thumb. It refers to the ability of the thumb to touch the tips of the other fingers, allowing grasping and manipulation. This movement involves the thumb opposing the fingers, hence the term.
B. False
False is incorrect because opposition is a well-defined movement in anatomy, particularly in the hand.
C. Only in the lower limbs
D. Only in the spine
Full Explanation
Choice A reason: Opposition is a specific movement that occurs primarily in the thumb. It refers to the ability of the thumb to touch the tips of the other fingers, allowing grasping and manipulation. This movement involves the thumb opposing the fingers, hence the term.
Choice B reason: False is incorrect because opposition is a well-defined movement in anatomy, particularly in the hand.
The protein that acts as a calcium receptor in skeletal muscle is:
A. Actin
Actin is a structural protein that forms the thin filaments in muscle fibers. It interacts with myosin during contraction but does not bind calcium directly or initiate contraction.
B. Tropomyosin
Tropomyosin is a regulatory protein that blocks the myosin-binding sites on actin in a relaxed muscle. It shifts position when calcium binds to troponin, but it does not itself bind calcium.
C. Titin
Titin is a large elastic protein that helps maintain the structural integrity of the sarcomere and contributes to passive elasticity. It does not function as a calcium receptor.
D. Troponin
Troponin is the correct answer. It is a regulatory protein complex that binds calcium ions during muscle contraction. This binding causes a conformational change that moves tropomyosin away from actin’s binding sites, allowing myosin to interact with actin and initiate contraction.
E. Dystrophin
Dystrophin is a structural protein that connects the cytoskeleton of muscle fibers to the extracellular matrix. It plays a role in muscle integrity but does not bind calcium or regulate contraction.
Full Explanation
Choice A reason: Actin is a structural protein that forms the thin filaments in muscle fibers. It interacts with myosin during contraction but does not bind calcium directly or initiate contraction.
Choice B reason: Tropomyosin is a regulatory protein that blocks the myosin-binding sites on actin in a relaxed muscle. It shifts position when calcium binds to troponin, but it does not itself bind calcium.
Choice C reason: Titin is a large elastic protein that helps maintain the structural integrity of the sarcomere and contributes to passive elasticity. It does not function as a calcium receptor.
Choice D reason: Troponin is the correct answer. It is a regulatory protein complex that binds calcium ions during muscle contraction. This binding causes a conformational change that moves tropomyosin away from actin’s binding sites, allowing myosin to interact with actin and initiate contraction.
Choice E reason: Dystrophin is a structural protein that connects the cytoskeleton of muscle fibers to the extracellular matrix. It plays a role in muscle integrity but does not bind calcium or regulate contraction.
The process of bones increasing in thickness is known as:
A. Appositional growth
Appositional growth is the correct answer. It refers to the process by which bones increase in diameter or thickness. This occurs when osteoblasts in the periosteum lay down new bone matrix on the outer surface, while osteoclasts resorb bone on the inner surface to maintain proper proportions.
B. Concentric growth
Concentric growth is not a recognized term in bone physiology. It may refer to circular layering in osteons but not to bone thickening.
C. Interstitial growth
Interstitial growth occurs within cartilage and is responsible for lengthening during development. It does not contribute to bone thickness.
D. Circumferential growth
Circumferential growth is a vague term and not commonly used in bone biology. It may imply growth around the circumference but is not the standard term for bone thickening.
E. Epiphyseal plate closure
Epiphyseal plate closure marks the end of longitudinal bone growth during adolescence. It does not relate to increasing bone thickness.
Full Explanation
Choice A reason: Appositional growth is the correct answer. It refers to the process by which bones increase in diameter or thickness. This occurs when osteoblasts in the periosteum lay down new bone matrix on the outer surface, while osteoclasts resorb bone on the inner surface to maintain proper proportions.
Choice B reason: Concentric growth is not a recognized term in bone physiology. It may refer to circular layering in osteons but not to bone thickening.
Choice C reason: Interstitial growth occurs within cartilage and is responsible for lengthening during development. It does not contribute to bone thickness.
Choice D reason: Circumferential growth is a vague term and not commonly used in bone biology. It may imply growth around the circumference but is not the standard term for bone thickening.
Choice E reason: Epiphyseal plate closure marks the end of longitudinal bone growth during adolescence. It does not relate to increasing bone thickness.