Blood Pressure and Vascular Regulation MCQs

Physiology · 39 free questions with answers & explanations.

1. The baroreceptor reflex is activated by increased arterial pressure sensed in the carotid sinus and aortic arch. The immediate cardiovascular response is:
2. Which of the following best describes the autoregulatory mechanism that maintains constant organ blood flow despite changes in perfusion pressure?
3. The arterial baroreflex arc rapidly corrects a sudden drop in blood pressure. Following a hemorrhage of 500 mL, carotid sinus baroreceptors fire less frequently. Trace the reflex response accurately.
4. Myogenic autoregulation maintains relatively constant blood flow to the kidney and brain despite mean arterial pressure changes from 70–180 mmHg. What is the cellular mechanism underlying the myogenic response?
5. Renin cleaves angiotensinogen to angiotensin I. The principal cell type secreting renin is the juxtaglomerular (JG) cell. Three independent signals stimulate renin release. Which signal acts via a Gs-coupled receptor on JG cells that is INHIBITED (not stimulated) by beta-blockers?
6. During haemorrhagic shock, which of the following cardiovascular responses occurs LAST as compensatory mechanisms are sequentially overwhelmed?
7. The Bainbridge reflex differs from the baroreceptor reflex in its response to blood volume expansion. Which statement best describes the mechanism and direction of the Bainbridge reflex?
8. Myogenic autoregulation of blood flow in the kidney involves which sequence of events when arterial pressure suddenly increases?
9. During hemorrhagic shock, the vasomotor center activates sympathetic outflow. Which cardiovascular reflex provides the most powerful short-term defense against a 30% blood volume loss?
10. Endothelium-derived relaxing factor (EDRF), identified as nitric oxide (NO), activates which enzyme and by what specific biochemical mechanism to cause vascular smooth muscle relaxation?
11. The arterial baroreceptor reflex provides rapid short-term blood pressure regulation. In a patient who stands up suddenly (orthostatic challenge), the sequence of baroreceptor-mediated compensatory events is:
12. Nitric oxide (NO) is a key endothelium-derived relaxing factor. The intracellular pathway by which NO causes vascular smooth muscle relaxation is:
13. Endothelin-1 (ET-1), secreted by vascular endothelial cells, is the most potent endogenous vasoconstrictor. ET-1 acts through two receptors: ETA on vascular smooth muscle and ETB on endothelial cells. The ETB receptor mediates which opposing action?
14. The cardiopulmonary baroreceptors (low-pressure receptors) in the walls of the atria and pulmonary vessels respond to volume overload. When activated by increased atrial pressure, they produce reflex changes via the Henry-Gauer reflex. What are these changes?
15. Pressure-natriuresis is the direct intrinsic renal mechanism by which elevated arterial pressure increases sodium and water excretion. The key intracellular mediator that reduces proximal tubule NHE3 activity during pressure-natriuresis is:
16. The myogenic response (Bayliss effect) in arterioles allows autoregulation of blood flow. The mechanism involves stretch-activated channels and leads to membrane depolarization and vasoconstriction. Which channels are primarily responsible for the initial depolarizing current in vascular smooth muscle during myogenic activation?
17. The arterial baroreceptor reflex responds to acute hypertension. The afferent limb of this reflex carries signals via cranial nerves IX and X to the nucleus tractus solitarius (NTS). From NTS, the efferent limb ultimately achieves vasodilation via inhibition of which rostral medullary nucleus?
18. The myogenic response of arterioles (Bayliss effect) enables pressure autoregulation in the cerebral and renal circulations. The molecular mechanism involves:
19. The long-term regulation of blood pressure is determined primarily by renal pressure natriuresis. According to the Guyton model, why can neurohormonal or vascular mechanisms alone NOT permanently raise blood pressure without renal involvement?
20. A 60-year-old patient has serum renin activity 0.4 ng/mL/hr (low) and serum aldosterone 32 ng/dL (high). She is hypertensive with hypokalemia. This biochemical pattern is most consistent with:
21. A patient is given an infusion of a drug that selectively increases vascular smooth muscle cAMP. Which vascular response is expected?
22. In Cushing's reflex (vasopressor response to raised ICP), the triad of hypertension, bradycardia and irregular breathing results from:
23. In the pressure-natriuresis relationship, chronically elevated arterial blood pressure leads to increased urinary sodium excretion, resetting the system. The intrarenal mechanism mediating pressure natriuresis involves:
24. In a patient with a renal artery stenosis-induced (Goldblatt) hypertension, which sequence of physiological events CORRECTLY describes the pathophysiology?
25. Nitric oxide (NO) produced by vascular endothelial cells causes vasodilation. Which intracellular mechanism mediates smooth muscle relaxation?
26. A researcher infuses a vasoactive substance into an isolated arterial segment and observes contraction that persists even after the substance is washed out. She then endothelium-denudes the same segment and repeats the experiment; the vasoconstriction now promptly reverses on washout. Which of the following BEST explains this observation?
27. A patient has a mean arterial pressure of 95 mmHg, cardiac output of 5 L/min, central venous pressure of 3 mmHg. What is the systemic vascular resistance in mmHg·min/L (Wood units)?
28. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) is the primary mediator of flow-mediated vasodilation. Which of the following correctly describes its mechanism of action on vascular smooth muscle?
29. During exercise, skeletal muscle blood flow increases up to 15-fold. Which local metabolic factor most potently causes functional hyperemia (exercise hyperemia) in skeletal muscle?
30. In a patient with severe haemorrhagic shock (class III, >30% blood volume loss), which compensatory response maintains mean arterial pressure for the longest duration?
31. The myogenic autoregulation of blood flow in renal and cerebral vessels is due to:
32. The Windkessel function of the aorta refers to:
33. Renal artery stenosis (RAS) causes renovascular hypertension. In unilateral RAS, the primary sustained mechanism of hypertension after the initial weeks is:
34. Baroreflex sensitivity is reduced in elderly hypertensive patients. Which consequence of impaired baroreflex function most directly causes orthostatic hypotension in this population?
35. In haemorrhagic shock (class III, ~30–40% blood volume loss), which of the following compensatory responses occurs?
36. The baroreflex is the fastest blood pressure regulatory mechanism. In a patient with autonomic neuropathy (e.g., diabetic), the baroreflex gain is severely reduced. What clinical finding best demonstrates this defect?
37. Nitric oxide (NO) causes vascular smooth muscle relaxation. Which downstream mechanism mediates this vasodilation?
38. The arterial baroreceptor reflex arc involves stretch receptors in the carotid sinus and aortic arch. In a patient who stands up rapidly (orthostasis), the sequence of baroreceptor responses is:
39. Nitric oxide (NO) is synthesised from L-arginine by endothelial nitric oxide synthase (eNOS). Its mechanism of vasodilation involves: