Final answer:
The latch state in vascular smooth muscle refers to a subset of cross-bridges between myosin heads and actin that remain locked together, keeping the filaments linked without ATP. This allows for muscle tone maintenance with low energy expenditure.
Step-by-step explanation:
The latch state in vascular smooth muscle refers to a subset of cross-bridges between myosin heads and actin that remain locked together, keeping the thick and thin filaments linked without the need for ATP. This allows for the maintenance of muscle tone in smooth muscle with very little energy expenditure. Smooth muscle in the walls of arterioles and visceral organs can maintain contractions in the latch state even as calcium is removed and myosin kinase is inactivated.