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A 21-year-old male visits with his family doctor at the urgingof his parents when home for Spring Break. The parents areconcerned because their son has lost a significant amount ofweight. The young man is concerned because he is experiencing aheart rate of 120bpm while at rest and much higher when exercising.Additionally, his blood pressure averages 137/82 based upon fourrecordings. He has a recurring headache, tremors in his hands andsuffers dyspnea.

This individual has been generally health for his entire life,eats a reasonably good diet and is very active, thus the abovesymptoms are concerning. Standard blood tests show normal levels ofblood cells, however there is an elevated amount of metadrenalines(metabolite by-product of adrenaline) and the urinalysis also showsan elevated amount of metabolites of catecholamines. The physicianthen orders a 24-hour urine test where the patient collects urineat regular intervals for a 24-hour period. The patient is warned toavoid stimulants such as cocoa and caffeine during this timeperiod. The results of this test confirm elevated metabolites ofcatecholamines. The physician suspects a condition calledpheochromocytoma, which is a (usually) non-cancerous tumor of theadrenal gland. This tumor causes the excess secretion ofcatecholamines. To confirm this suspicion, the physician orders aspecialized type of CT scan, called MBIG. This type of scanutilizes radioactive iodine as a contrast agent for visualizationof masses as described above. A sample of MIBG results is shownbelow:

The MIBG confirms the presence of a tumor on the adrenal glandand the young man is scheduled for surgery to remove the mass. Itis non-cancerous and he resumes his life. As a side note, currentestimates are that only about 10% of adrenal tumors arecancerous

7. What is normal heart rate and bloodpressure for a healthy, active 21-year-old male? How do the heartrate and blood pressure of this patient compare? Explain themechanism by which catecholamines modify blood pressure. (2pts)