This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
The latch bridge mechanism helps in which of the following in smooth muscles? 
Select and explain. 
A. Initiation of contraction, B. Sustained contraction, C. Early dephosphorylation, D. None of the above
B: Sustained contraction
Answer: B: Sustained contraction 
Explanation: Latch bridge mechanism is one in which myosin cross bridges remain attached to actin for some time after cytoplasmic Ca2+ concentration falls. This causes sustained contraction with little ATP. This is of impoance in smooth muscles. Ref: Ganong's, Review of medical physiolgy, 21st Edition, Page 84