Because your heart puts out what your organs need at any given time, it sends more blood to your GI system when you eat and drink
Your body has an intricate communication system that not only signals when your stomach needs more blood, but also supplies feedback to your heart when it meets the tissue’s need.
Blood pressure is a major player in this system and increases as needed. Your heart can supply blood, but it takes the work of the arterial walls to get the blood to your stomach.
Your arteries accomplish this by raising the pressure to increase the rate of blood flow. Your elevated blood pressure returns to normal when the digestive process is complete.