The liver provides a critical interface between body and food. Digestion facilitates absorption of nutrients and other substances into the blood. Unfortunately, some of these substances are potentially toxic and cannot be incorporated into cellular components or excreted from the organism without chemical modification. Blood from the intestine goes to the liver through the hepatic portal vein, carrying with it all absorbed food components. Toxic chemicals might be found in this mix, such as plant alkaloids (for example, mushroom toxins), drugs, or chemicals formed during food processing. Hepatic architecture is based on inflow and outflow of blood from the microanatomical units making up the whole organ, and known as lobules or acini, each about 4–5 mm in diameter. Areas around the points of entry of blood into each lobule are called periportal, whereas areas around the outflow of blood from each lobule are called pericentral.