Liver - Flexikon

From Old Greek: hepar - Leber
German: Leber

The liver is the central organ of the entire metabolism. The most important functions of this organ are:

Decomposition and expulsion of substances
Production of essential proteins
Utilization of food components

Table of contents

1. Overview

2. Anatomy

6. Important liver diseases

Overview

The liver is the largest digestive gland in the adult human body. It generates several [[blood proteins99, antibodies and bile, and is the main detoxification organ. Almost all nutriments that are absorbed in the blood from the intestine initially arrive at the liver, and then based on requirement these are released into the blood or eliminated from the blood. Other functions of the liver are the storage of vitamins and the synthesis of initial products for hormone production.

Anatomy

The liver of a human adult weighs approximately between 1400 and 1800 gm. It is a soft, fairly smooth structured organ that is situated in the right upper abdomen. The liver can be macroscopically subdivided into 4 different lobes:

Lobus hepatis dexter
Lobus hepatis sinister
Lobus quadratus hepatis
Lobus caudatus hepatis

For further details see: Liver anatomy

Functions

The liver is closely involved in the metabolism of glucose, fat and proteins. Glucose is absorbed from the intestinal blood supply and passes it on to the rest of the body in a controlled way. A surplus is stored as glycogen. In times of hunger, the stored substance is metabolized to glucose. The liver influences the blood sugar level through the control of hormones (e.g. insulin) and can keep it constant independent of the food supply. Insulin activates the “burning�? of the sugar in the liver and checks the decomposition of fat.

Overview

Storage
- Glucose in the form of glycogen,
- Fat in the form of lipoproteins
- Several vitamins and iron
- Blood

Generation of proteins
Generation of bile
Synthesis of cholesterol and bile acids
Decomposition and detoxification
- Decomposition of hemoglobin resulting in bilirubin
- Metabolism of ammonia into urea
- Hormones
- Medicaments
Defense function (germs from the GIT)
Hematopoiesis in the fetus up to the 7th month of pregnancy.

Liver enzymes

In case of liver diseases, the blood test shows valuable evidences of the type and extent of the disease. Enzymes are needed in the liver, like elsewhere in the body, to sustain its metabolic activities. In case of damage to the liver cells, these enzymes can be found in increased quantities in the blood serum. Based on the increase in the type of enzyme, one can infer the type of the disease. The magnitude of the enzyme increase corresponds to the extent of the damage to the liver cells. Cell damages can be caused by, among others, virus infections, alcohol, poisoning or tumors.

All enzymes in the liver cells can also be found in other body cells, like for instance in the heart and skeletal muscles.

The liver enzymes often measured are:

Alanine aminotransferase (ALT), obsolete: serum glutamate pyruvate transaminase (SGPT)
Aspartate aminotransferase (AST), obsolete: glutamate oxalacetate transaminase (GOT)
Glutamate dehydrogenase (GLDH)
Gamma-glutamyltransferase (GGT)¹
Alkaline phosphatase (AP)

1:The GGT is one of the most sensitive parameters for damages of the liver cells and the bile duct system.

Diagnostics

Anamnesis
Palpation
Inspection (skin marks, ascites and edema)
Laboratory diagnostics
- Bilirubin (direct and indirect)
- Bilirubin excretion in urine
- GOT, SGPT, GGT, GLDH, alkaline phosphatase
- CHE, quick value and albumin
- Hepatitis serology
- Serum iron, serum ferritin, copper and Ceruloplasmin level
Imaging procedures
Liver biopsy