A 47 year old teacher goes to her physician complaining of dizziness, fainting, and
shortness of breath. She appears pale and chronically ill. Her heart rate is 70/min supine
and 68/min sitting and standing. Her blood pressure is 120/74 supine, 98/54 sitting, and
84/48 standing. Heart sounds and lung sounds are normal. Her abdominal exam and her
general neurologic exam are both normal. Routine lab exams are normal.

Question 1: Identify any abnormal data in the description of this patient.

Several studies were performed to evaluate the patient's circulatory control mechanisms. She
was placed on a tilt table which allows rapid changes in the patient's orientation. Her blood
pressure while supine was 102/60. She was then tilted to a 45º heads-up position and her blood
pressure fell to 70/35. There was no change in her heart rate when tilted.

Question 2: What possible mechanisms could account for this result?

Failure to maintain a nearly constant blood pressure in changing posture from the supine to the
erect is called orthostatic hypotension.

Question 3: List all the functional locations within the cardiovascular system where pathology or
dysfunction could lead to failure to activate the baroreceptor reflex upon standing.

Administration of 2 mg of atropine (an antagonist of muscarinic receptors) intravenously did not
result in any change in heart rate.

Question 4: Is this response normal? How can you account for this result?

Isoproterenol (a ? -adrenergic agonist) administration resulted in her heart increasing from
60/min to 118/min. Stimulated release of catecholamines from sympathetic nerve endings (via
administration of an MAOI) produce a rise in blood pressure.

Question 5: Are these responses normal? What do they tell you?

Question 6: Where in the system do you believe the patient's problem lies? Why?

Please provide discription of all the answers.