Known as the second largest organ in the body after the skin, the liver has over 500 functions, including helping the blood to clot and breaking down damaged cells. Weighing between two and three pounds, it holds about 13 percent on the body’s total blood volume. The liver has the distinction of being both a gland and an organ. As an organ, it can execute chemical actions, and as a gland, it secretes chemicals for other parts of the body to use.
One of the main functions of the liver is to remove toxins from the body including, but not limited to, pollution, fumes, and alcohol. It achieves this through the process of oxidation: together, liver enzymes and oxygen burn toxins. The result is combined with amino acids so the burned toxins can be removed through bile or as urine.
In partnership with the pancreas, the liver balances blood sugar by metabolizing carbohydrates. The liver removes extra sugar from the blood and stores it as glycogen. When blood sugar gets too low, for example, it breaks down the stored glycogen and releases it in the blood until sugar levels are normalized. If blood sugar levels are high, the liver absorbs glucose in response to insulin.
As a gland, the liver produces 800 to 1000 mL of bile a day with the help of the gallbladder, which sits right under it. This dark-green or yellowish fluid contains organic substances such as acid and cholesterol. It helps digest fats and vitamins in the small intestines, to prepare them for absorption or elimination.
Not only does the liver rid the body of harmful substances, but it also helps fight infections by mobilizing the Kupffer cells, part of the macrophage system. Macrophages are the immune system's white blood cells that consume harmful substances in the body, such as bacteria. Kupffer cells reside specifically in the liver. They kill any bacteria they encounter and are particularly helpful when it comes to fighting intestinal infections.
The liver is a very accommodating organ. In addition to adjusting its size to match the host, it can regenerate. Due to disease, a doctor may need to remove part of a person's liver. Provided that the sickness isn’t too advanced, the excised parts will grow back. Experts say a liver that is 40 percent of its normal size will repair itself completely after one month, provided there are no complications.
Plasma proteins are transporters of fats, vitamins, minerals, and hormones. They help in a variety of ways, including maintaining blood pH. The liver synthesizes three types of plasma proteins, and albumin is the most abundant. The protein is rich in essential acids such as lysine and arginine and is vital to maintaining proper pressure and distribution of water and fluids between blood and tissues.
A red blood cell lives about 120 days before it starts to disintegrate. The hemoglobin from disintegrated red blood cells breaks down into four parts: globin, protein, iron, and heme. Heme eventually reduces into an orange-yellow pigment called bilirubin. This waste product moves to the liver, where it becomes more soluble and is combined with bile; the excretory system then excretes it as feces and urine.
Among its many functions, metabolizing fats is key for the liver. Once glycogen stores are full, additional glucose is turned into fatty acids. The blood transfers cholesterol and fatty acids, storing them in fat tissues. Too much extra fat can cause the liver to become fat, which can impair its function.
Ammonia is a naturally occurring byproduct of bacteria that works in the intestines as well as the cells that process protein. The highly toxic waste product must be removed from the body or it will damage the central nervous system. Because ammonia is insoluble, it passes through the liver and converts to urea, then moves on to the kidney to leave the body as urine.
As a gland, the liver not only clears cholesterol from the body but also produces it. The liver produces most of the cholesterol in your body and is needed to make vitamin D, digestive enzymes, and hormones. Since it can’t travel alone in the bloodstream, it’s combined with low-density and high-density lipoproteins. Excess cholesterol is combined with bile so the liver can eliminate it.
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