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Figure 3.19 The Autonomic Nervous System
The autonomic nervous system has two divisions: The sympathetic division acts to energize the body, preparing it
for action. The parasympathetic division acts to calm the body, allowing it to rest.
Our everyday activities are controlled by the interaction between the sympathetic and
parasympathetic nervous systems. For example, when we get out of bed in the morning, we
would experience a sharp drop in blood pressure if it were not for the action of the sympathetic
system, which automatically increases blood flow through the body. Similarly, after we eat a big
meal, the parasympathetic system automatically sends more blood to the stomach and intestines,
allowing us to efficiently digest the food. And perhaps you’ve had the experience of not being at