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Describe the structure of the liver and explain its

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Introduction

Describe the structure of the liver and explain its functions in maintaining homeostasis The liver is the largest organ in our body it weighs about 1.5kg, it is situated in the abdomen just below the diaphragm. The liver helps to regulate the composition of the blood, it has two blood supplies the hepatic artery and the hepatic portal vein and also has a blood removal hepatic vein. The hepatic artery carries oxygenated blood from the dorsal aorta, whilst the hepatic portal vein carries deoxygenated blood from the gut. The hepatic vein is responsible for carrying deoxygenated blood from the liver to the inferior vena cava; these blood vessels are known as the interlobular vessels. The structure of the liver consists of a large number of lobules, these are cylindrical in shape and each one is approximately 1mm in diameter. Each lobule consists of liver cells arranged in rows radiating from the centre towards the margin. Liver cells are similar although they have many different functions; however they have large numbers of mitochondria and a large Golgi Apparatus. In the centre of each lobule there is a branch of the hepatic vein this is known as the central or intralobular vein. ...read more.

Middle

To maintain the regulation of lipids the liver can absorb them, they can either be broken down to form glycogen or transported to the fat depots. Amino acids are proteins which are not stored in the body like carbohydrates and lipids therefore excess amino acids are destroyed by the liver cells in a process called deamination. This is where the amino group NH2 is removed from the amino acid by the formation of ammonia. 2 NH2RCHCOOH + O2 ROCOCOOH + NH3 Amino acid Oxygen Amino acid residue Ammonia The amino acid residue then enters the Kreb's triacarboxylic acid cycle and is oxidized to release energy. The ammonia must not be allowed to accumulate because it is highly toxic even in very small quantities. The ornithine cycle is a reaction when the ammonia reacts with carbon dioxide to form the less toxic urea which is transported in the bloodstream from the liver to the kidneys for elimination from the body in the urine. 2 NH3 + CO2 CO(NH2)2 + H2O Ammonia Carbon dioxide urea water Another function of the liver to maintain homeostasis is the synthesis of proteins, this is when the liver synthesizes some important proteins, and the serum protein fibrinogen is a protein involved in the clotting of blood after injury. ...read more.

Conclusion

Iron globin complex is broken down into amino acids which are used for protein synthesis by the liver, the iron is used for the synthesis of new haemoglobin by the liver cells. The formation of red blood cells are produced by the liver in a foetus but this function is done by the bone marrow after birth. The adult liver plays a very important function in red blood cells formation, it synthesizes the haematinic principle from vitamin B12 which is stored in the liver. If there is a deficiency of this vitamin pernicious anaemia develops where there will be a drastic reduction in the red blood cells. The liver makes many chemicals which are toxic less harmful this is called Detoxification. Deamination converts ammonia to urea. Hydrogen peroxide, a toxic by product of certain metabolic pathways, is converted into oxygen and water by catalyse, an enzyme in the liver. Excess insulin from the pancreas is broken down by enzymes in the liver. After they have performed their functions, sex hormones are modified in the liver and then excreted either in the bile or via the kidneys. The food preservative benzencarboxylic is joined to glycine, an amino acid, to form N-benzolyglycine which is excreted in the urine. Ethanol is processed by the liver cells. ?? ?? ?? ?? Nicci Waterfield Human Anatomy 1 ...read more.

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