The liver is one of the body's largest and most active organs, located in the upper right abdomen under the diaphragm. It matters because it processes nutrients, removes harmful substances, produces bile, stores energy, and makes important blood proteins. Nearly everything absorbed from the digestive tract passes through the liver before reaching the rest of the body.
This makes the liver a central control station for metabolism and chemical balance.
Key Facts
- The hepatic portal vein brings nutrient-rich blood from the digestive organs to the liver.
- The hepatic artery brings oxygen-rich blood from the heart to the liver.
- Hepatic blood flow is about 25 percent of cardiac output at rest.
- Glucose can be stored as glycogen after meals and released as glucose between meals.
- Bile helps emulsify fats, increasing surface area for digestive enzymes.
- Albumin and many clotting factors are synthesized by liver cells called hepatocytes.
Vocabulary
- Hepatocyte
- A hepatocyte is the main liver cell type responsible for metabolism, bile production, detoxification, and protein synthesis.
- Bile
- Bile is a fluid made by the liver that helps break large fat droplets into smaller droplets during digestion.
- Hepatic portal vein
- The hepatic portal vein is the blood vessel that carries nutrient-rich blood from the intestines and other digestive organs to the liver.
- Liver lobule
- A liver lobule is a small functional unit of the liver where blood flows past hepatocytes and toward a central vein.
- Glycogen
- Glycogen is a branched storage form of glucose found mainly in the liver and muscles.
Common Mistakes to Avoid
- Thinking the liver only detoxifies poisons is wrong because the liver also controls glucose levels, makes bile, stores vitamins and minerals, and synthesizes plasma proteins.
- Confusing the hepatic portal vein with the hepatic vein is wrong because the portal vein carries blood into the liver from the digestive tract, while hepatic veins drain blood out of the liver to the inferior vena cava.
- Assuming bile contains digestive enzymes is wrong because bile mainly contains bile salts, pigments, cholesterol, and other substances that help emulsify fats rather than chemically digest them.
- Treating all liver blood as oxygen-rich is wrong because the liver receives mixed inputs: oxygen-rich blood from the hepatic artery and nutrient-rich, lower-oxygen blood from the hepatic portal vein.
Practice Questions
- 1 A liver receives 1.5 L of blood per minute. If 75 percent comes from the hepatic portal vein, how many liters per minute come from the hepatic portal vein and how many come from the hepatic artery?
- 2 A student eats a meal containing 90 g of carbohydrate. If 30 g of the absorbed glucose is stored in the liver as glycogen, what fraction and what percent of the carbohydrate was stored as liver glycogen?
- 3 Explain why the liver is positioned to receive blood from the intestines before that blood enters general circulation, and describe one advantage of this arrangement.