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Function of the Golgi Body.

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Introduction

Function of the Golgi Body P1 The golgi body, also known as golgi apparatus or golgi complex. It is a network of stacked sacs found within nucleated cells. The golgi body stores, packages and distributes the proteins and lipids made in the endoplasmic reticulum. Proteins, which are meant to return to the endoplasmic reticulum, carry a distinctive tag. The golgi apparatus recognises the tag and transports the proteins back to the endoplasmic reticulum. However some proteins and lipids are sent to the surface of the cell to be released into the external environment. Structure and Function of Epithelial Tissues P2 Structure: The epithelial tissue is the layer of cells covering the outside of organs and the skin. These types of cells are firmly attached to each other and rest on a basement membrane, they also have a free surface. There are many different types of epithelial tissue all depending on how many layers and the shape of the individual cells. 1. Simple Epithelium - has only one layer of cells. It can either be : * Squamous - which are thin and flat. (1) * Cuboidal - these are cube shaped with a central spherical nucleus. ...read more.

Middle

The gallbladder is a muscular organ, which is a membranous sac often pear-shaped. It is found on the under-surface of the right lobe of the liver. Functions of the liver The liver has many functions including: * Digestive functions Digestive functions are carried out by bile, which is produced in the liver. * Metabolic functions The liver is very important for homeostasis because it directly determines the concentration of many different substances in the blood plasma. These activities are called metabolic or regulatory functions, these include: * Regulation of blood glucose * Regulation of lipids * Regulation of aminoacids * Regulation of plasma proteins * Storage of vitamins and minerals * Production of heat * Storage of blood * Excretory functions Excretion is the removal from the body of the waste products of the metabolism and of substances surplus to the body's requirements. * Production of urea Urea can only be formed in the liver, if ammonia is left to accumulate in the blood it will cause problems. * Break down of blood cells Red blood cells are continually being produced in the bone marrow and have a life spa of 129 days. ...read more.

Conclusion

The amount of glycogen formed is controlled by a hormone called insulin, this is produced by the pancreas. This hormone acts mainly by prompting the uptake of glucose by the membranes of the liver and muscle cells. In the human liver up to 60g of glucose can be stored in the form of glycogen and 150g in the muscles. Once this limit has been reached, excess glucose is converted into molecules of fat, which then leave the liver through the vein and are taken up for storage by adipose cells, mostly under the skin. The process of glycongenolysis is controlled by two hormones, glucagon from the pancreas and adrenalin form the adrenal glands. They are released in response to a fall in blood glucose but adrenalin can also be produced in times of stress so it boosts the availability of glucose quickly. * When animals have not eaten for several hours, hepatic glycogen reserves become exhausted. The hepatocytes recognise the problem and activate other enzymes to start synthesising glucose out of other substances, like fats or amino acids, if the fasting is prolonged. This process is known as gluconeogenesis, and it is controlled by the hormone glucagon. The ability of the liver to synthesise glucose this way is greatly important to carnivores, whose diet in the wild has virtually no starch. 1 ...read more.

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