When a muscle is not contracting, actin and myosin are prevented from reacting by:
Correct Answer: Troponin-tropomyosin
Description: When a muscle is not contracting, actin and myosin are prevented from reacting by troponin-tropomyosin. Tropomyosin covers the active sites on actin filaments which prevents myosin heads from attachment. Troponin must bind with Ca++ in order to cause the tropomyosin to move off the active sites. Phosphocreatine has a high energy phosphate bond which is used to reconstitute ATP. Heavy meromyosin refers to the heavy chains in the myosin filament. Acetylcholinesterase and acetylcholine are at the neuromuscular junctions and do not directly affect actin and myosin crossbridge formation. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 5. Excitable Tissue: Muscle. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds),Ganong's Review of Medical Physiology, 24e.
Category:
Physiology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now