When a person's blood pressure rises, the haemostatic mechanism to compensate for an elevation involves stimu… - RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Applied Physiology

Medium

Appeared in: RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Explanation

A rise in blood pressure causes stretching of the arterial walls, which is the specific stimulus for baroreceptors (pressure sensors), not chemoreceptors.
To compensate for high blood pressure, the body must lower it. This is achieved by reducing factors that increase pressure.
The baroreceptor reflex accomplishes this by signaling the brain to inhibit the sympathetic nervous system.
Inhibition of sympathetic output causes vasodilation (widening of blood vessels), which reduces peripheral resistance and directly lowers blood pressure.

Option A: Chemoreceptors are the wrong type of sensor for this stimulus. Furthermore, stimulating the sympathetic nervous system would cause vasoconstriction and an increased heart rate, which would raise blood pressure even higher, opposing the needed compensation.
Option B: Chemoreceptors are not the primary sensors for blood pressure changes. They respond to chemical alterations in the blood (O₂, CO₂, pH).
Option C: While baroreceptors are the correct sensor, the response described is wrong. Inhibiting the parasympathetic nervous system would cause the heart rate to increase, which would counteract the goal of lowering blood pressure.

Visual 1: Diagram: The Baroreceptor Reflex Arc. This visual should illustrate the complete negative feedback loop: 1. High BP stimulus. 2. Stretch of baroreceptors in the carotid sinus and aortic arch. 3. Afferent nerve signals to the medulla. 4. Inhibition of sympathetic and stimulation of parasympathetic pathways. 5. Efferent signals to the heart (decreased rate) and blood vessels (vasodilation). 6. Resulting decrease in BP.

Clinical Relevance

Nursing practice connection: Knowing Blood Pressure Regulation and Baroreceptor Reflex helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The baroreceptor reflex is the body's primary mechanism for rapid, moment-to-moment adjustments in blood pressure, crucial for maintaining stable blood flow to the brain when changing posture (e.g., standing up).
Many antihypertensive medications work by targeting parts of this pathway. For example, beta-blockers reduce the heart's response to sympathetic stimulation, and vasodilators directly relax the smooth muscle of blood vessels.
What if the patient has autonomic neuropathy (common in long-standing diabetes)? The baroreceptor reflex can become blunted or ineffective. This puts the patient at high risk for orthostatic hypotension (a sudden drop in BP upon standing), leading to dizziness, syncope, and falls.

How to Approach the Question

First, identify the core physiological event in the question stem: a rise in blood pressure.
Next, determine the body's goal: to compensate by lowering the blood pressure back to normal (homeostasis).
Consider the sensors involved. For mechanical pressure changes, the primary sensors are baroreceptors. For chemical changes (O₂, CO₂), they are chemoreceptors. This allows you to eliminate options A and B.
Evaluate the remaining options based on the required outcome. To lower blood pressure, the body needs to decrease cardiac output (e.g., slow heart rate) and/or cause vasodilation (decrease resistance).
Recall that the sympathetic nervous system generally increases heart rate and causes vasoconstriction (raising BP). Therefore, to lower BP, the sympathetic system must be inhibited.
This logic confirms that baroreceptors must inhibit the sympathetic nervous system to cause vasodilation, making this the correct compensatory mechanism.

Concept Tested & Keywords

Q5C8j4mXJjuhQ7Dg4Ely3i