Life is dull with an unhealthy liver. How much body functionalities does this silent organ bear in our bodies?
Metabolism of carbohydrates (e.g. glucose)
When you are hungry and have low blood sugar: It breaks down glycogen in the liver to provide glucose to the body.
When you are even hungrier: Convert some non-carbohydrate materials such as amino acids (through protein breakdown), lactate, pyruvate, and glycerol (through fat breakdown) into glucose through gluconeogenesis.
When your blood sugar is too high:
a. It converts glucose back into glycogen and store it in the liver.
b. It breaks down glucose into smaller but yet more functional components, such as pyruvate.
Pyruvate has the abilities to:
1. Enter the Krebs cycle2. To be converted into ketone bodies or fatty acids.
3. To be converted into lactate.
In other words, excess blood sugar may not all be stored as glycogen. It may be consumed by other reactions in the body in the form of ATP or become the visible fat on the stomach that everyone knows about.
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Metabolism of Fat
The liver secretes bile and stores it in the gallbladder to help dissolve fats in our diet. When fats are converted into smaller components such as triglycerides, fatty acids, and cholesterol, these smaller molecules are packaged into chylomicrons, like packages waiting to be labeled with apoproteins.
Apoproteins, such as apo A1 and A2, are the structural components of high-density lipoproteins (HDL), commonly known as good cholesterol.
Apo B100 is the structural component of low-density lipoproteins (LDL), commonly known as bad cholesterol.
Apo C2 acts like an instruction label, directing tissues containing lipoprotein lipase, such as fat or skeletal muscle, to break down the triglycerides in the package into a form that can be utilized by our bodies.
Chylomicrons + apoproteins = lipoproteins, which are forms of fat transportation in blood. There are good cholesterol and bad cholesterol:
High-density lipoproteins (HDL)
Identified by the label codes apo A1 and A2, produced by intestinal cells. The more the HDL , the lower the risk of cardiovascular disease.
Low-density lipoproteins (LDL)
Derived from intermediate-density lipoproteins (IDL), identified by apo B100. When body tissues need cholesterol, they synthesize LDL receptors on their cell membranes, just like raising a hand and requesting a package from a courier. The liver also recognizes apo B100 and absorbs LDL, unloading its cholesterol.
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Synthesis and Metabolism of Proteins
Protein synthesis
The liver synthesizes most of the proteins in the blood, except for immunoglobulins.
Protein metabolism
After proteins are broken down into amino acids, they are converted into pyruvate or ketone bodies in the liver. Additionally, nitrogen-containing compounds such as proteins produce ammonia (NH3) during metabolism, which can be harmful to the body. At this point, the liver takes on the responsibility of protecting the body by synthesizing urea to reduce the harmful effects of ammonia.
Blood
a. Produces heparin to prevent blood clotting.
b. Aging red blood cells are destroyed by macrophages in the tissues and converted into hemoglobin, which is then further broken down into bilirubin. The liver converts bilirubin into water-soluble bilirubin diglucuronide and secretes it into the bile duct for elimination.
Bilirubin is the main cause of the yellow color in our bile and stool. In some severe liver diseases, the liver is unable to effectively eliminate bilirubin from the blood, resulting in a yellowing of the skin known as jaundice.
Detoxification, drug elimination, alcohol metabolism
The liver contains various enzymes that detoxify the body, eliminate consumed drugs, and the enzyme alcohol dehydrogenase (ADH) is responsible for alcohol metabolism.
