What is the role of tropomyosin in skeletal muscles?
Tropomyosin serves as a contraction inhibitor by blocking the active sites on the myosin molecules.
Tropomyosin is the chemical that activates the myosin heads.
Tropomyosin serves as a contraction inhibitor by blocking the active sites on the actin molecules.
Tropomyosin serves as a calcium inhibitor in the synaptic cleft.
Tropomyosin is the receptor for the motor neuron neurotransmitter.
The Correct Answer is C
Choice A reason: This is incorrect. Tropomyosin does not block myosin; it blocks the active sites on actin filaments, preventing myosin binding until calcium binds to troponin.
Choice B reason: Tropomyosin is not a chemical activator. Activation of myosin heads occurs through ATP hydrolysis and calcium-mediated exposure of actin binding sites.
Choice C reason: This is correct. Tropomyosin is a regulatory protein that wraps around actin filaments and blocks myosin-binding sites. When calcium binds to troponin, tropomyosin shifts, exposing these sites and allowing contraction to proceed.
Choice D reason: Tropomyosin does not function in the synaptic cleft nor inhibit calcium there. Calcium regulation in the synaptic cleft involves neurotransmitter release mechanisms, not tropomyosin.
Choice E reason: Tropomyosin is not a receptor. The receptor for motor neuron neurotransmitters (e.g., acetylcholine) is the nicotinic acetylcholine receptor located on the sarcolemma of the muscle cell.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is True
Explanation
Choice A reason: Slow oxidative fibers are rich in mitochondria, myoglobin, and capillaries, making them highly efficient at aerobic metabolism. They contract slowly but are highly resistant to fatigue, making them ideal for prolonged activities like marathon running or maintaining posture.
Choice B reason: This is incorrect. Fast glycolytic fibers are suited for short bursts of power, not endurance. Slow oxidative fibers are specifically adapted for sustained, low-intensity activity.
Correct Answer is C
Explanation
Choice A reason: Circumduction is a circular movement that combines flexion, extension, abduction, and adduction. It is typically seen in ball-and-socket joints like the shoulder or hip, not in the neck. It does not describe the backward bending of the head.
Choice B reason: Rotation refers to the movement of a bone around its longitudinal axis, such as turning the head side to side. It does not involve bending the head backward.
Choice C reason: Hyperextension occurs when a joint is extended beyond its normal anatomical position. In the case of the head, bending it backward past the neutral anatomical position is a classic example of hyperextension.
Choice D reason: Flexion is the movement that decreases the angle between two body parts, such as bending the head forward toward the chest. It is the opposite of the movement described in the question.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.