What Does the Liver Do?

by admin on July 28, 2009

Don’t mess with your liver. It serves a vital function in almost every system in your body; from hormone and digestive enzyme production to blood filtration and the last stop in chemical digestion of medications. It is both an endocrine and exocrine organ, and along with the heart, brain and pancreas is an organ that we cannot live without. Read further to find out just what the liver does in your body.

Exocrine Functions

An exocrine organ secretes substances that leave your body – think “exit” and “exocrine”.  Your digestive tract is one long tube, open at both ends that receives enzymes and other materials to enable nutrient absorption. Mammary glands produce milk and mucus glands secrete mucus; all of which are destined to leave the body. In contrast, endocrine organs secrete chemicals into the bloodstream for use by the body. The adrenal glands release adrenaline into the blood to physically prepare us for danger.  The hypothalamus produces a myriad of hormones to regulate bodily functions.

The liver produces bile that is stored in the gallbladder to be secreted into the small intestine before eventually leaving the body; making bile production an exocrine function. Bile emulsifies fats – breaks the large lipid molecules into smaller pieces, creating more surface area to ease digestion. This is why people without gallbladders can’t have a lot of fatty foods at one time. The liver is able to produce enough bile for immediate use, but can’t stockpile enough bile to digest a Big Mac and large fries.

Your liver also manufactures some very important hormones (endocrine function). It produces Insulin-Like Growth Factor (IGF 1); a hormone responsible for stimulating body growth in children. Thrombopoietin is a hormone produced by the liver that regulates platelet production in your bone marrow. “Thrombo” refers to blood clotting and “poietin” refers to stimulating cell multiplication. I am a big believer in breaking down words into their roots. The body becomes much easier to understand if you know anything “hepatic” is pertaining to the liver, “angio” to the heart, “renal” to the kidneys and so on.

Your liver, along with your kidneys, are an important organ in glucose metabolism. The liver converts glucose into glycogen. Glycogen provides the body with short term energy storage. Long term energy storage is contained in fat cells. Muscle cells can also convert glucose to glycogen. “Gluco” refers to sugar. The liver converts glycogen back to glucose for immediate use. Gluconeogenesis is the process of making glucose (genesis) from “new” products. Specifically, this refers to making glucose from amino acids, lactate and other non-sugar substances. Gluconeogenesis occurs in times of fasting and exercise – generally after all easily available reserves have been used up. To summarize, glycogenesis is the opposite of glycogenolysis (lysis means to break apart).

The liver makes cholesterol and tryglycerides; important components of hormone production. Thank your liver for those elevated cholesterol levels. Through a relatively complicated chemical synthesis, the liver converts glucose into triglycerides by attaching a glycerol to every three glucose. Cells in the body use triglycerides in their endoplasmic reticulum; the site of protein and hormone production (endo means inside and plasma refers to the cytoplasm inside a cell). Fatty liver is a disease in which the liver enlarges with excess triglycerides. Since the liver is the site of triglyceride manufacture, a vicious cycle occurs when the body has too much glucose, the liver busily makes the glucose into triglycerides at an increased rate to match those higher levels. The body uses as much triglycerides as it can, and the rest builds up in the liver; having no where else to go. Alcoholism and obesity are common causes of fatty liver disease. Do you eat fois gras? You are eating the diseased liver of obese birds. Farmers force feed geese and ducks corn boiled in fat to create fatty liver disease. It is the excess fat that gives their liver the rich and buttery taste. There are major ethical debates world wide about this practice, but I digress..

The liver is where old red blood cells go to die.  Bilirubin and biliverdin are waste products from red blood cell metabolism. Some is added to bile to aid in fat digestion and some is filtered through the kidneys to give  urine its trademark yellow color. The bile portion makes its way through the small and large intestine to give feces its trademark brown color. Jaundice, the disease in which the skin and eyes become  yellow results from a blood excess of bilirubin. The liver normally collects and secretes bilirubin into bile, but if it is not functioning properly, bilirubin builds up in your blood and becomes toxic.

The liver is the site of drug metabolism and in some cases drugs can become temporarily more toxic to the body during the digestion process as their constituents become more concentrated. Some drug metabolites are secreted into bile and others into urine. In addition to drug metabolism, the liver has cells that filter antigens out of the blood. Anti in this case refers to antibody and gen refers to generating; so antigen literally means “antibody generating”. The liver is one of the many immunological organs in the human body.

The liver stores vitamins and minerals for short and long term use including Vitamin A, Vitamin D, Vitamin B12, iron and copper and in case I haven’t already made a case for taking care of your liver, be aware that it is responsible for making albumin, the plasma protein responsible for maintaining blood osmolarity – the concentration of dissolved solutes for a given amount of liquid. If your blood osmolarity is out of whack, you risk bleeding internally. The cells in your body will either shrink up and die from losing water or swell up and burst from taking in too much water.

One more major function; the liver makes angiotensinogen, a precursor to angiotensin, the hormone responsible for increasing blood pressure in times of fluid loss, or elevated blood cortisol levels.

With all of these major functions, it is a wonder that we don’t get sick with liver related problems even more than we already do. Take  heart (or liver – tee hee); the liver is the only human organ capable of regeneration. You can grow a new liver from only 25% of a full liver! Someone doesn’t have to die for you to receive a transplant!

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