GMS 6410 Exam 2 - Exam questions and answers

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Studocu is not sponsored or endorsed by any college or university GMS 6410 Exam 2 - Exam questions and answers Circulation Of Blood (University of Florida) Studocu is not sponsored or endorsed by any college or university GMS 6410 Exam 2 - Exam questions and answers Circulation Of Blood (University of Florida) Downloaded by zee (zezejacks@gmail.com) lOMoARcPSD|29469330

Distance Learning GMS 6410 Exam #2 Your name: Rachel Chandler Answer each question using ~2-5 sentences. When finished, upload on the Assignments page in Canvas. Dr. Scheuer “Baroreflex” You are helping to run a clinical trial for a Rheos device (to chronically stimulate baroreceptor afferents) to determine if it can significantly lower blood pressure in hypertensive patients. You also have control, normotensive participants. You measure arterial baroreceptor function in all study participants. A. How could you test baroreflex function in the participants (i.e. what would be your independent and dependent variables)? B. What differences would you expect in baroreflex function between the normotensive and hypertensive patients? C. If you could measure nerve activity in the Rostral Ventral Lateral Medulla (RVLM) during a rapid increase in arterial pressure in a normotensive participant, what would you expect to observe just before and during the increase in arterial pressure? D. How would stimulation of (i.e. activation of the neurons in) the RVLM influence renal control of sodium excretion? State if there would be an increase, decrease or no change in sodium excretion and describe the mechanism. E. How would stimulation of (i.e. activation of the neurons in) the Caudal Ventral Lateral Medulla (CVLM) influence renin secretion? State if there would be an increase, decrease or no change in renin excretion and describe the mechanism. A. To test baroreflex function in the participants, your independent variable could be the lowering of blood pressure and the dependent variable, which is measured and recorded, would be the heart rate of the patient. B. In the normotensive patients, you would expect normal increases in heart rate as blood pressure is reduced however in hypertensive patients, there will not be an increase in heart rate as there will be a difficulty lowering blood pressure. C. Just before and during the increase in arterial pressure, you would expect to see a stimulation to the medulla and a release of GABA in the RVLM. D. Stimulation of neurons in the RVLM would influence renal control of sodium excretion because the RVLM is the final common efferent pathway responsible for acute BP as well as blood flow increases and is largely responsible for sympathetic nervous activity. This area will serve to influence renal control of sodium excretions because there will be an increase in sympathetic nervous system activity and alpha-2 receptors will be stimulated which will serve to produce large increases in blood pressure and blood flow as well as cause an increase in renal sodium excretion. E. Stimulation in the Caudal Ventral Lateral Medulla would mean that there has been an increase in the blood pressure which causes increased stimulation of the Downloaded by zee (zezejacks@gmail.com) lOMoARcPSD|29469330

CVLM. The increased blood pressure as part of the baroreceptor reflex will now try to be decreased which will result in a decrease of renin release. Renin in the body serves as an enzyme that acts on angiotensinogen which results in the release of angiotensin 1 which serves to increase blood pressure. Dr. Keller-Wood “Baroreflex in Pregnancy” Pregnancy involves adaptations of the cardiovascular system to the new state. A. In human pregnancy, what change in the baroreflex occurs? How is this change reflected in the blood pressure and heart rate measured in pregnant women when they are quietly sitting or lying down? B. Other than heart rate, what other measures of baroreflex output (ie the efferent limb of the reflex) are altered? C. What consequences does the change in the baroreflex have on the response to standing in a pregnant woman? D. What effect on the baroreflex occurs in women with preeclampsia or pregnancy induced hypertension? E. Name two factors that investigators have proposed as mechanisms responsible for the change in baroreflex responses in pregnancy. A. In pregnancy, the baroreflex changes because of profound cardiovascular changes caused by increased blood flow and decreased arterial pressure. Increased blood flow means an increase in cardiac output during pregnancy resulting in increased resting heart rate as well as blood flow. There is also decreased uterine vascular resistance as more blood flow is needed to the uterus and decreased resistance in renal circulations as well as smaller constrictor responses and larger dilator responses. Regarding standing and lying down, a lower regulated set point of blood pressure is found during pregnancy and studies have found that cardiac output decreases when pregnant women change from standing to laying down. During pregnancy, blood pressure decreases, and heart rate increases in any position which is contrary to what you would believe. B. Other than heart rate, renal sympathetic nerve activity is an efferent nerve activity that is altered because of baroreflex alteration in pregnancy. Blood volume as well as cardiac output increase by somewhere from 30 to 50% during pregnancy as well. C. Due to baroreflex dysfunction and the changes caused during pregnancy, is it shown that a consequence for pregnant women is that they have an impaired sympatho-vagal balance and late gestation women have hypotension immediately after standing. It is also shown that standing for pregnant women produces smaller increases in heart rate, plasma epinephrine and sympathetic nerve recording. D. In women with preeclampsia or pregnancy induced hypertension, pregnancy induced hypertension is associated with a further increase in sympathetic firing. Also, there is evidence that there may also be a further re-set or desensitization of the baroreflex after hypertension is established in pregnant women. In Downloaded by zee (zezejacks@gmail.com) lOMoARcPSD|29469330

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