HSC are also considered to play a role in the genesis of portal hypertension upon contraction and causes a decrease in the diameter of the sinusoids. Several growth factors such as platelet derived growth factor (PDGF) and transforming growth factor β1 (TGF-β1) as well as pro-inflammatory cytokines are responsible for the activation of HSC. This results in increased synthesis and secretion of various ECM components. Myofibroblasts can amplify the processes of early fibrosis by paracrine recruitment of other HSC and by autocrine stimulation via transforming growth factor β1 (TGF-β1) (R. Bataller & Brenner, 2005). Thus, HSC play an important role both in hepatic fibrosis and to preserve the equilibrium in the matrix components, since they not …show more content…
only produce components of the ECM, but also produce enzymes for their degradation (Safadi & Friedman, 2002). 1.3 Physiological Functions of the Liver The liver regulates the levels of most chemical compounds in the blood and excretes bile, which helps to remove waste products from the liver. It filters the blood coming from the digestive tract before transporting it to the rest of the body. The liver processes this blood and detoxifies chemicals and toxins and metabolizes alcohol and drugs. Although the liver performs more than 500 different activities, the following are the three most important hepatic functions (Triger, 1979): • Vascular functions (storage and filtration) • Metabolism of carbohydrates, proteins and fats • Bile Formation and Secretion • Detoxification and Drug Metabolism 1.3.1 Vascular Functions (Storage and Filtration) Liver plays an important role in the detoxification and purification of blood from the digestive tract. It is a large, venous organ that makes it one of the largest reservoirs of blood in the body and can hold up to 1L of blood at a time. On the other hand, the internal surfaces of all hepatic sinusoids are covered by a high number of Kupffer cells that can phagocytize parasites, viruses, bacterial endotoxins and immunocomplexes (A. L. Jones, 1996). 1.3.2 Metabolism The metabolic functions of the liver such as the synthesis of carbohydrates, proteins and fats are carried out by the hepatocytes. 1.3.2.1 Carbohydrate Metabolism The liver plays a major role in the metabolism of carbohydrate. This includes the storage of glycogen, conversion of galactose and fructose to glucose, gluconeogenesis, and formation of important chemical compounds from intermediates of carbohydrate metabolism. The liver is an organ of particular importance in maintaining normal concentrations of blood glucose. When the glucose concentration increases above normal values, the excess is removed via glycogen synthesis and glycolysis. When a blood glucose deficit occurs, the liver releases it via glycogenolysis. Among the main controlling factors of reversible glycogenolysis / gluconeogenesis changes are the concentration of substrates, hormone levels, hepatocellular hydration status, hepatic innervation and hepatocyte zonal heterogeneity (Zakim, 1996). 1.3.2.2 Fat Metabolism Although fat metabolism can occur in almost all cells in the body, some aspects of fat metabolism occur more rapidly in the liver than in other cells. The specific functions of the liver in lipid metabolism are as follows: • β-oxidation of fatty acids and formation of acetoacetic acid • Lipids and lipoproteins synthesis • Cholesterol and phospholipid synthesis • Conversion of large amounts of carbohydrates and proteins into fats • Detoxification of toxic endogenous molecules as well as other hepatotoxins (A.
D. a. E. Cooper, J.L., 1996) 1.3.2.3 Protein Metabolism Liver is the principal site for protein metabolism. Although the liver plays a vital role in carbohydrate and fat metabolism, its function in protein metabolism is of critical importance, as the failure to do so for more than a few days can result in death. This includes deamination and transamination of amino acids, urea formation to remove ammonia from body fluids, formation of approximately 90% of all plasma proteins, and synthesis of non-essential amino acids (Donohue Jr, 1996). 1.3.3 …show more content…
Detoxification The liver plays a central role in the detoxification and elimination of endogenous toxic molecules such as ammonia in the form of urea via urea cycle, as well as hepatotoxins such as ethanol, acetaminophen and other drugs and other xenobiotics. Liver effectively detoxifies ammonia generated from the breakdown of all amino acids via the well-established Krebs’ urea cycle (A. J. L. Cooper, 1996). The process of detoxification occurs in three major stages performed by three sets of cellular proteins or enzymes, called the phase I (transformation) enzymes, phase II (conjugation) enzymes, and the phase III (transport) proteins. Whereas enzymes involved in phase I including cytochrome P450 (CYP450), flavin containing monooxygenase (FMO), alcohol dehydrogenase (ADH), and aldehyde dehydrogenase (ALDH) mainly conduct hydrolysis, oxidation, and reduction reactions; enzymes of phase II mostly conduct conjugation reactions such as glutathione conjugation, glucuronidation, sulfation, methylation, acetylation, and amino acid conjugation. Finally, in phase III, transporter proteins such as the ATP-binding cassette transporters move glutathione, sulfate, and glucuronide conjugates out of cells into the bile for elimination (Macherey, 2008). 1.3.4 Bile Formation and Secretion One of the many functions of the liver is the formation and secretion of bile.
Bile is an aqueous secretion that has organic and inorganic components whose osmotic concentration is similar to that of plasma. An adult human usually secretes between 600 and 1200 mL of bile per day. The liver secretes bile in two stages; in the initial stage the hepatocytes produce a secretion containing large amounts of bile acids, cholesterol metabolism and other organic constituents that are discharged into the bile canaliculus, that then flow into terminal bile ducts, and finally to the hepatic duct and common bile duct, from which it is emptied directly into the duodenum or diverted through the cystic duct into the gallbladder. In the second stage of bile secretion, the epithelial cells of the bile duct, cholangiocytes contribute to bile secretion via the release of an aqueous solution of bicarbonate (Fitz,
1996).
Gallstones form when the liquid stored in the gallbladder hardens into pieces of stone-like material. The liquid, called bile is used to help the body digest fats. Bile is made in the liver, and then stored in the gallbladder until the body needs to digest fat. At that time, the gallbladder contracts and pushes the bile into a tube—called the common bile duct—that carries it to the small intestine, where it help with digestion.
come along, this is when the bile is released to digest the fat. The same
The liver plays central role in each of these phases of clotting process, as it synthesizes the majority of coagulation factors and proteins involved in fibrinolysis as well as thrombopoietin., which is responsible for platelet production from megakaryocytes. In cirrhosis, liver is badly get damaged. So the production of coagulation factors and proteins is impaired. Many pathological processes associated with cirrhosis, such as portal hypertension and endothelial dysfunction as well as co-morbid conditions, may also alter the coagulation process. Consequently, patients with liver disease as in cirrhosis, have a disturbed balance of procoagulant and anti- coagulant factors which deviates from the normal coagulation cascade.
Proteins are one of the main building blocks of the body. They are required for the structure, function, and regulation of the body’s tissues and organs. Even smaller units create proteins; these are called amino acids. There are twenty different types of amino acids, and all twenty are configured in many different chains and sequences, producing differing protein structures and functions. An enzyme is a specialized protein that participates in chemical reactions where they serve as catalysts to speed up said reactions, or reduce the energy of activation, noted as Ea (Mader & Windelspecht).
The development of the heart is a complicated process that implicates cell specification and differentiation, including tissue formation, shaping and alteration, to create a functional organ. The zebrafish has become a potential model system to disentangle the fundamental genetic, molecular, and cellular mechanisms of cardiac development and function. The liver is one of the essential organ in mammals. It performs many functions such as help the body digest food, store energy, and remove poisons. The liver also completes many regulatory functions that are critical to fetal development and to life in general. However, failure to perform theses function can result in many mammal liver diseases. Hepatomegaly is a symptom that associate with several liver disorders. Surveys had shown that a large number of the death in the US is caused by chronic liver disease. Liver cancer is another type of liver diseases that is one of the main cause of cancer-related death worldwide.
The pancreas can be divided into two sections when studying the histology. The pancreas has exocrine and endocrine functions, each with unique cell types. The exocrine pancreas serves to secrete digestive enzymes into the duodenum. Some of the specific enzymes and secreted substances are Proteases, lipase, amylase, bicarbonate, and water (Bowen, “Exocrine Secretions”). These enzymes are used to break down protein, fat, and carbohydrates respectively. The bicarbonate simply act as an acid buffer to prevent damage of the small intestine as the stomach acid must be neutralized. The enzymes are created in acinar cells and the bicarbonate is synthesized in epithelial cells surrounding pancreatic ducts (Bowen “Exocrine
The Hepatitis A Virus affects many different systems within the body. The first being the digestive system and the gastrointestinal system because Hepatitis A causes an acute liver infection. The liver’s job is to process nutrients, filter the blood and toxin from your body, and fight infections. It produces important blood components, proteins, and bile which helps you digest food. The liver also stores glucose and vitamins. The Hepatitis A Virus causes inflammation that interrupts the liver’s ability to perform these vital functions. Having a healthy liver is crucial to your health because it supports many other body systems. For example, one function of the liver is to produce bile which is needed to break down fats. The body stores bile in the gallbladder and then sends it to the beginning section of the small intestine. Bile is then combined with other digestive
Liver disease resulting from alcohol affects more than two million Americans and is one of the primary causes of illness and death. The liver frees the body of harmful substances, such as alcohol. While the liver breaks down alcohol, it produces toxins that can be even more dangerous than the alcohol consumed (“Beyond Hangovers: Understanding Alcohol's Impact on Your Health” 13). “These by-products damage liver cells, promote inflammation, and weaken the body’s natural defenses. Eventually, these problems can disrupt the body’s metabolism and impair the function of other organs” (“Beyond Hangovers: Understanding Alcohol’s Impact on Your Health” 13).
What is hepatic cirrhosis? According to the medical dictionary hepatic cirrhosis is when scar tissue replaces the liver’s healthy tissue. This disease changes the structure of the liver and blood vessels that nurture it. It reduces the liver’s capability to produce proteins and process hormones, nutrients, medications, and poisons. Cirrhosis is an illness that gets worse over time and possibly can become life threatening. This serious illness is ranked as the ninth leading cause of death in the U.S. It is the third most common cause of death for adults between 45 and 65 years of age. It occurs in more than fifty percent of undernourished chronic alcoholics. Unfortunately it kills about 35,000 people per year. In other country’s such as Africa and Asia death from cirrhosis is usually caused by hepatitis B.
When eaten, protein is broken down into amino acids. Proteins and amino acids are used for almost every metabolic process in the body, and are the building blocks for every tissue in your body.
the body's chemical reactions are all made of protein. Without the right proteins, blood won't clot properly and cuts won't heal. Carbohydrates and fat can't meet your energy needs, proteins can. broken down and used as a source of emergency energy. So this makes protein is very crucial for your health.
Zein, N. N., & Edwards, K. (2009). The Cleveland Clinic guide to liver disorders. New York: Kaplan Pub.
Scientists, coaches, and athletes have recognized that periodized strength training promotes increase in skeletal muscle size, increase in force, and increase of the regenerating capacity of the muscle cells.
Moderation is vital in all aspects of life and is necessary for overall health, including with one’s food intake. Protein is one of the many important nutrient building blocks that is necessary for proper growth and good health. However, eating excessive amounts of any nutrient or inadequate amounts, can cause various health concerns. Scientists have been able to estimate the amount of nutrients that the body requires. However, the amount of any particular nutrient varies from person to person, depending on your “age, sex, general health status, physical activity level, and use of medications and drugs” (Schiff 2013). It is also important to remember that consuming the required amount of nutrients that meets your dietary guidelines does not
It is then secreted within the small intestine where it helps to break down ethanol, fats and other acidic wastes including ammonia, into harmless substances.