AIIMS Bhuvneshwar NO…: Peripheral resistance depends on?

AIIMS Bhuvneshwar NO- 2018

Applied Physiology

Easy

Appeared in: AIIMS Bhuvneshwar NO- 2018

Explanation

Peripheral resistance is the opposition to blood flow primarily determined by the tone and diameter of blood vessels.
Arterioles are known as 'resistance vessels' because their muscular walls allow for significant changes in diameter (vasoconstriction and vasodilation).
According to Poiseuille's Law, resistance is inversely proportional to the fourth power of the vessel's radius (R ∝ 1/r4).
This relationship means that even a small change in the diameter of arterioles causes a large, exponential change in overall peripheral resistance and, consequently, blood pressure.

Option A: Stroke volume is the amount of blood pumped by the heart per beat. It is a primary determinant of cardiac output (BP = CO x SVR), not peripheral resistance (SVR).
Option B: Veins are highly compliant 'capacitance vessels' that hold about 75% of the body's blood volume. Their contraction affects venous return and cardiac preload, not systemic resistance.
Option D: Blood volume influences the overall pressure within the cardiovascular system. While it is a component of blood pressure regulation, it does not directly determine the resistance to flow, which is a function of vessel caliber and blood viscosity.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Determinants of Peripheral Vascular Resistance as background academic context rather than a clinical decision trigger.
Understanding peripheral resistance is crucial for managing hypertension. Many antihypertensive drugs, such as calcium channel blockers and ACE inhibitors, work by causing vasodilation, which decreases peripheral resistance and lowers blood pressure.
In conditions like septic shock, widespread vasodilation causes a dramatic drop in peripheral resistance, leading to life-threatening hypotension.
Atherosclerosis leads to stiffening and narrowing of arteries, which chronically increases peripheral resistance and is a major cause of hypertension.

How to Approach the Question

This is a factual recall question based on cardiovascular physiology.
First, identify the core concept in the question stem: 'Peripheral resistance'.
Recall the basic formula for blood pressure: Blood Pressure (BP) = Cardiac Output (CO) × Systemic Vascular Resistance (SVR), where SVR is another term for peripheral resistance.
Analyze the given options to determine which one is a direct component of SVR.
Recognize that arterioles, with their muscular walls, are the primary vessels that regulate resistance by changing their diameter.
Eliminate options related to cardiac output (Stroke volume, Blood volume) and venous function (Degree of contraction of veins), as these do not directly determine resistance in the arterial system.

Concept Tested & Keywords

QRA7WB69tT6xLmk9y6r-wR

E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 25-27

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 3 p. 52-54