## STORAGE AND METABOLIC ROLE OF LIVER ### Anatomy and Blood Supply The liver is a large, vital organ with a complex structure and a unique dual blood supply. - **Structure:** - Composed of a larger *right lobe* and a smaller *left lobe*. - Lobes contain thousands of smaller functional units called **lobules**. - Lobules are connected to **bile ducts**, which transport bile from the liver to the small intestine. - **Dual Blood Supply:** The liver receives blood from two distinct sources, ensuring it is supplied with both oxygen and nutrients from the digestive system. | Blood Vessel | Type of Blood | Function | | :--- | :--- | :--- | | **Hepatic Artery** | Oxygenated blood | Supplies the liver cells with the oxygen needed for metabolic activities. | | **Hepatic Portal Vein** | Nutrient-rich, deoxygenated blood | Carries absorbed nutrients (and toxins) from the stomach and intestines directly to the liver for processing. | ### Major Metabolic and Regulatory Functions The liver performs over 500 vital functions, acting as the body's primary metabolic hub. 1. **Digestion:** Produces **bile**, which emulsifies fats in the small intestine, aiding digestion and carrying away waste products. 2. **Protein Synthesis:** Produces essential **blood plasma proteins**, such as *serum albumin* (maintains osmotic pressure), *globulins* (immune function), and *fibrinogen* (blood clotting). 3. **Lipid Metabolism:** Synthesizes **cholesterol** and special proteins that transport fats throughout the body. 4. **Carbohydrate Metabolism:** Regulates blood glucose levels by converting excess glucose into **glycogen** for storage (*glycogenesis*) and converting glycogen back to glucose when energy is needed (*glycogenolysis*). 5. **Amino Acid Regulation:** Monitors and regulates the blood levels of **amino acids**, the building blocks of proteins. 6. **Storage and Recycling:** Processes hemoglobin from old red blood cells to recycle its **iron content**, which is then stored in the liver. 7. **Detoxification (Urea Cycle):** Converts toxic **ammonia** (a by-product of protein metabolism) into **urea**, a less toxic substance that is excreted by the kidneys. This is a critical part of the body's excretory system. 8. **Detoxification (General):** Clears the blood of drugs, alcohol, and other poisonous substances by metabolizing them into non-toxic or easily excretable forms. 9. **Blood Clotting:** Produces key proteins and factors necessary for regulating blood clotting. 10. **Immunity:** Resists infections by producing immune factors and removing bacteria from the bloodstream. 11. **Waste Removal:** Clears **bilirubin** (a breakdown product of red blood cells). Failure to do so leads to an accumulation, causing jaundice (yellowing of the skin and eyes). ### Excretion of Waste Products After the liver breaks down harmful substances, the by-products are excreted: - **Via Bile:** By-products enter the intestine and are eliminated in the **feces**. - **Via Blood:** By-products are filtered from the blood by the kidneys and eliminated in the **urine**.