please answer all the questions. Next, you do another test where you have Alex p
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please answer all the questions.
Next, you do another test where you have Alex perform ischemic exercise for as long as he is able 6 to do so. Blood is withdrawn from the patient every few minutes or so during the exercise period. a. Alex's blood samples are tested for lactate and 3. 50 o 40 o 30 20 control compared with a control sample of a patient who does not suffer from a glycogen storage disease. The results are shown in Figure 25.1. Why does lactate concentration increase in the normal patient? Why is there no corresponding increase in Alex's lactate concentration? patient 0 5 10 15 20 25 30 Time, minutes b. Urine tests after Alex has completed his Figure 25.1: Blood lactate concentration following ischemic exercise in a patient with a glycogen storage disease and a control. (Based on Stanbury, et al., 1978.) exercise reveal the presence of myoglobin in his urine. Myoglobin isn't normally found in the urine, but in muscle cells. Why does Alex suffer from myoglobinuria following ischemic exercise? Alex's blood samples are also tested for alanine content. In a normal person, you would expect that blood alanine would increase during ischemic exercise. But in Alex's blood samples, you see a decrease in alanine concentrations, leading you to believe that Alex's muscle cells are taking up alanine rather than releasing it. Why would blood alanine concentrations increase in a normal person? Why do blood alanine concentrations decrease in your patient? c. 4. Alex's enzyme deficiency does not cause him to suffer from either hypo- or hyperglycemia. Explain 5. As a treatment, you tell Alex that the best thing he can do is to avoid strenuous exercise. If he does wish to exercise, you advise him to consume sports drinks containing glucose or fructose frequently while exercising. Why would this help alleviate Alex's suffering during exercise?Explanation / Answer
Answer 3. a. As we know that end product of glycolysis is pyruvic acid. Pyruvic acid is subsequently converted into lactic acid with the release of hydrogen ions. The compound that remains reacts with either sodium or potassium to form a salt named as lactate. Formation of lactate is necessary because it allows for the continued metabolism of glucose through glycolysis. Lactate is cleared from the blood by either through oxidation within the muscle fiber in which it was produced or by getting transported to other muscle fibers for oxidation. Lactate which is not oxidized by these ways diffuses into capillaries and goes to the liver via blood where it is converted into glucose. This glucose is then either used up by the working muscles or stored in the liver as Glycogen.
Glycogen storage disease is of 6 types. It seems that Alex is suffering from type 5 glycogen storage disease in which muscle glycogen accumulates and lactic acid is not produced by adrenalin or ischemia as a result of muscle phosphorylase deficiency. Now if lactic acid is not produced lactate will not form and that is why we don't see a sharp increase of blood lactate in Alex's test results.
Answer 3 b. In a severe condition or during strenuous ischemic exercise, the destruction of muscle tissue releases a protein called myoglobin, which is filtered through the kidneys and released in the urine thus causing myoglobinuria.
Answer 3 c. Protein is an important fuel for exercising muscles and that is why amino acid is needed in more amount during strenuous exercises. During ischemic exercise, transamination of glutamate by alanine aminotransferase leads to increased levels of alanine in muscle and plasma. That is why we see more alanine levels in normal person during exercise. But in case of Alex's disease, the level of an enzyme called Alanine transaminase is increased. The function of Alanine transaminase is to convert alanine to pyruvate and glutamate and that is why you see a decreased level of alanine in Alex's case when compared to a normal person.
Answer 4. .......
Answer 5. In Alex's condition the enzyme required to convert glycogen to glucose is impaired and that is why his working muscles are not getting the appropriate amount of glucose that is required. If he exercises he loses all the blood glucose quickly and thus feels strained and cramped but if he takes sports drinks containing glucose during exercise his working muscles will be able to get the appropriate amount of glucose that is required. This is how taking sports drinks with glucose will alleviate Alex's suffering during exercise.
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