JBL EMT Practice Exam

The autonomic nervous system is responsible for controlling involuntary functions in the body, such as heart rate, digestion, respiratory rate, and pupil contraction. In the context of respiration, while the autonomic nervous system influences the rate and depth of breathing, the voluntary act of holding one's breath (breath holding) is not directly controlled by the autonomic nervous system. This is why option A, "Breathing," is the correct answer. Options B, C, and D are controlled by the autonomic nervous system. Option B, "Breath holding," is a voluntary action rather than an involuntary function like those controlled by the autonomic nervous system. Option C, "Digestion," is regulated by the autonomic nervous system through the sympathetic and parasympathetic divisions. Finally, option D, "Vessel dilation," is a function controlled by the autonomic nervous system to regulate blood flow and blood pressure in the body.