Ketones in insulin resistant state Essay Example for Free

Ketones in insulin resistant state Essay 1. How is glucose normally maintained in the post absorptive state? 2. Why is muscle glycogen not useful for blood glucose 3. Why may this situation have evolved 4. Under what circumstances do you think substantial gluconeogenesis will occur 5. What is necessary for the production of ketones 6. What will reduce acetyl CoA oxidation 7. When is oxaloacetate availability impaired 8. When is the regulation of gluconeogenesis disrupted Glycolysis and gluconeogenesis are reciprocally regulated by eachother. What promotes the activity of one inhibits the other. Lack of insulin leads to high levels of glucose in the blood, gluc levels exceed renal threshold. . this causes excess water to excreted in urine (polyuria) Ketones are formed when there is not enough sugar or glucose to supply the body’s fuel needs. This occurs overnight, and during dieting or fasting. During these periods, insulin levels are low, but glucagon and epinephrine levels are relatively normal. This combination of low insulin, and relatively normal glucagon and epinephrine levels causes fat to be released from the fat cells. The fats travel through the blood circulation to reach the liver where they are processed into ketone units. The ketone units then circulate back into the blood stream and are picked up by the muscle and other tissues to fuel your body’s metabolism. In a person without diabetes, ketone production is the body’s normal adaptation to starvation. Blood sugar levels never get too high, because the production is regulated by just the right balance of insulin, glucagon and other hormones.However, in an individual with diabetes, dangerous and life-threatening levels of ketones can develop. When there is not enough insulin, the fat cells keep releasing fat into the circulation, and the liver keeps making more and more ketones and ketoacids. The rising ketoacid levels make the blood pH too low (acidotic/Diabetic Keto-Acidosis), which is an emergency medical situation and requires immediate medical attention. Oxidation reaction†¦ leads to release of h+ ions Lipogenesis: Since carbohydrates are the major part of the diet, they must be immediately converted into energy, stored as glycogen, or converted into fats. The introduction has already presented the facts about the necessity of storing energy as fat. A total of 55% of the carbohydrates are involved in the synthesis of fats. The total energy content of the diet must be balanced with the energy requirements of the human body. If excess foods (calories) are ingested beyond the bodys energy needs, the excess foods (energy) are converted into fat. If insufficient calories are ingested, the energy deficit is made up by oxidizing fat reserves. These simple facts provide the key to weight control although it is probably more easily understood than carried out in practice. Excessive deposits of lipids lead to an obese condition. Extensive blood capillary networks in these deposits mean that they are quite active metabolically. Obesity puts a strain on the heart by causing it to pump blood through extra c apillaries. Generally, obesity results from overeating, but a few people have malfunctioning endocrine glands. Lipid metabolism is in a constant state of dynamic equilibrium. This means that some lipids are constantly being oxidized to meet energy needs, while others are being synthesized and stored. In rats, the average life-time of a single lipid molecule ranges from 2 to 10 days. A similar figure probably applies to human lipid metabolism. The sequence of reactions involved in the formation of lipids is known as Lipogenesis. Lipogenesis is not simply the reverse of the fatty acid spiral, but does start with acetyl CoA and does build up by the addition of two carbons units. The synthesis occurs in the cytoplasm in contrast to the degradation (oxidation) which occurs in the mitochondria. Many of the enzymes for the fatty acid synthesis are organized into a multienzyme complex called fatty acid synthetase. The major points in the overall lipogenesis reactions are: Starvation and Diabetes Synthesis of Ketone Bodies: When the body is deprived of food whether by voluntary or involuntary fasting, starvation is the net result. During starvation, glycogen reserves are rapidly depleted and the body begins to metabolize reserves of fat and protein. The entry of acetyl CoA into the citric acid cycle depends on the availability of oxaloacetic acid for the formation of citric acid. In starvation or uncontrolled diabetes situations, oxaloacetic acid is used to synthesize glucose and is then not available for use with acetyl CoA. Under these conditions, acetyl CoA is diverted from the citric acid cycle to the formation of acetoacetic and 3-hydroxybutanoic acids. In three steps, two acetyl CoA react to make acetoacetic acid. The acetoacetic acid may be changed into either acetone or 3-hydroxybutanoic acid. All three compounds are collectively known as ketone bodies even though one is not a ketone. The odor of acetone may be detected on the breath of a person with excess ketone bodies in the blood. The overall accumulation of ketone bodies in blood and urine is known as ketosis. The acids also upset buffers in the blood to cause acidosis. Both acetoacetic acid and 3-hydroxybutanoic acid can be used by the heart, kidneys, and brain for metabolism to produce energy. The heart and kidneys actually prefer these to glucose. In contrast, the brain prefers glucose, but will adapt if necessary in starvation or diabetic conditions. Link to: Ketone Bodies (move cursor over arrows)