Digestion is a complicated process that requires coordination between the digestive, circulatory, and nervous systems. The body must reroute extra blood to the small intestine and stomach. To compensate for this, the heart beats harder and faster, and blood vessels farther from the digestive system narrow. This allows the body to maintain blood pressure and blood flow to other parts of the body, such as the brain and lungs. Sometimes the body fails to respond in a way that maintains adequate blood pressure throughout the body.

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