If the radius of blood vessels of a person decreases, the blood pressure will be –

If the radius of blood vessels of a person decreases, the blood pressure will (a) increase. This phenomenon is governed by Poiseuille’s law, which states that blood flow is directly proportional to the fourth power of the vessel radius. When the vessel radius decreases, the resistance to blood flow increases exponentially, leading to higher blood pressure. This increased resistance requires the heart to pump harder to maintain adequate blood flow to tissues and organs. Consequently, systemic blood pressure rises. This effect is consistent across genders, as changes in vessel radius affect blood pressure universally. Therefore, narrowing of blood vessels, whether due to vasoconstriction or structural changes, can significantly impact blood pressure regulation, potentially leading to hypertension and associated cardiovascular complications if left uncontrolled.