1 Quiz 08 Results Name Quiz 08a Attempt Score 1.42963 Attempts 135 (Total of 137 attempts for this assessment) Question 1: Multiple Choice Average Score 0.46296 points Which one of the following would not cause hypocalcemia? Correct Percent Answered chronic kidney failure 1.481% a vitamin D deficiency 2.222% damage to parathyroid glands during surgery to remove thyroid tumors 3.704% a mutated parathyroid hormone receptor that auto-activates even in the absence of PTH 92.593% Unanswered 0% Question 2: Multiple Choice Average Score 0.48889 points A woman who had successfully given birth and breast-fed two previous children had great difficulty during the birth of her third child. Excessive blood loss during delivery caused necrotic damage to her pituitary gland (Sheehan’s syndrome). Which one of the following best describes the expected consequences of such damage? Correct Percent Answered inability to breast-feed her newborn infant 1.481% intolerance to cold 0% lethargy due to lack of energy 0% all of the above 97.778% a and b 0% b and c 0.741% Unanswered 0% Question 3: Multiple Choice Average Score 0.47778 points A mother brings her 16-month-old baby girl to a pediatrician because she thinks the baby is growing more slowly than normal. The doctor notes that the baby’s thyroid gland is greatly enlarged. He orders some blood tests. The results show that the baby’s plasma levels of T4 are low and plasma levels of TSH are high. Which one of the following is unlikely to be true? Correct Percent Answered The baby is usually lethargic. 0.741% The baby has a low body temperature. 0%2 The baby has not yet attempted to walk. 1.481% The baby’s brain development is retarded. 2.222% The baby has bone structure typical of that of a healthy 2-year old. 95.556% Unanswered 0% Question 4: Essay Average Score 0 points A female student suffers from anorexia nervosa. One afternoon she is rushed to the emergency room because of an irregular heartbeat. Her breath has the smell of an aromatic hydrocarbon (like acetone). Blood and urine samples reveal ketonemia and ketonuria, respectively. Why do you think she is having the irregular heartbeat? Very helpful hint: As the kidneys excrete excess H+, they reabsorb K+. Given Answers Anoreixa nervosa would imply hypoglycemia; this would imply that the body would begin to secrete glucagon in order to compensate. This promotes lipolysis, which would break down adipocytes. Through fatty acid metabolism, Acetyl-CoA becomes in excess and breaks down into keto acids ACA and BHB. These ketoacids decrease the pH of the blood, implying an excess of H+ ions. When the kidney excretes H+, it reabsorbs K+. Having an elevated extracellular level of potassium would initially depolarize cells, which would activate but then quickly inactivate sodium channels. This would inhibit the voltage gated sodium channels in t-tubules from perpetuating a depolarization and allow for muscle contraction, which would cause the irregular heart beat. Because the student is anorexic, her body uses fatty acid for metabolism to provide enough energy for her body. The process of using fatty acids for metabolism produces a large amount of ketoacid, lowering the pH of body fluid, which leads to the hypothesis of the student suffering from ketoacidosis. With ketoacidosis, as the kidney secretes excess H+, it also reabsorbs K+ at a much higher rate (hyperkalemia), which leads to depolarization of the heart cell and causing irregular heartbeat. Since she is literally starving herself, her body is lacking the proper glucose it needs for metabolism and energy production. This meaan that her body will break down other energy stores such as proteins and fats in order to compensate. In this case, her body is breaking down fat to use it as energy, and producing excessive amounts of ketones as well. This causes her body to be overly acidic. When she excretes the extra H+ ions, her body is reabsorping the K+. This hyperkalemia results in depolarization of the cardiac muscle, leading to irregular heartbeat. The student is mostly likely starving. Her body is resorting to breaking down fatty acids to use for fuel. Fatty acids can be converted to acetyl-CoA and used in the citric acid cycle to produce ATP. The result of this process is the production of acidic ketone bodies which can lower the blood pH when incorporated into the blood stream. As the kidney excrete excess H+ ions, they also reabsorb K+ ions. The increase of potassium ions in the bloodstream would lead to increased depolarization of heart muscle cells and thus more frequent inactivation of voltage-gated Na+ channels. This would explain why the student is suffering from an irregular heartbeat. The student is anorexia so she is very low on energy. She does not eat and does not have enough glucose for metabolism. Therefore, her body has to resort to breaking down fatty acids for energy. This produces ketones or keto acids and so she gets ketoacidosis because it makes her body very acidic. If the body is acidic (high in H+) it will want to excret H+. Thus, it must reabsorb K+ to balance out. This causes hyperkalemia and the heart beat is irregular. Because she is going through ketosis and the as ketone is going thorugh citric acid cycle, it produces ketone acids which spontaneously produces H+. As kidnety excretes excess H+, they reabsorb K+, as the plasma concentation of potassium gets higher, the cell becomes depolarized, and this leades to neuronal hyperexitability, which explains the irregular heartbeat.3 She is having an irregular heartbeat due to the increasing amounts of K+ in her system, which leads to an imbalance of this ion within her body. Elevated levels of potassium lead to the development of hyperkalemia, which can take a toll on the heart. Potassium is important in regulating a normal heart rate. Potassium plays a role in determining electrical current within the heart. An increase in potassium can disrupt this electrical potential and cause a problem with the heart rate since the levels will affect the ability of which an electrical charge can pass through the heart. Because she is anorexic, her body is does not have enough glucose to be converted into ATP by oxydative phosphorylation so her body is using up ketones for energy, which are fats produced by the liver during periods of starvation. The energy stores that are running her body are depleting