Final answer:
The body responds to a sudden decrease in arterial blood pressure in the brain by utilizing baroreceptors to trigger sympathetic stimulation, leading to increased heart rate, stronger heart contractions, and vasoconstriction of peripheral arterioles to restore blood flow and pressure.
Step-by-step explanation:
If the arterial blood pressure in the brain is suddenly decreased, the immediate response is a decrease in the flow through the arterioles to the brain. However, the body has compensatory mechanisms that involve baroreceptors, which are pressure sensors located in the carotid arteries and aorta, to detect such changes in blood pressure. Decreased pressure causes these baroreceptors to reduce their rate of firing, which in turn triggers an increase in sympathetic stimulation. This results in the heart increasing its rate and the force of its contractions, and the peripheral arterioles undergoing vasoconstriction. As a result, blood flow to the brain is restored and blood pressure increases. This is part of an autonomic reflex that helps maintain cerebral perfusion during sudden changes in blood pressure.