What You're Seeing: Blood flows through vessels in layers. In smooth vessels, these layers slide past each other in organized, parallel streams (laminar flow). In rough vessels with plaque, the flow becomes chaotic with swirls and eddies (turbulent flow).

Why Turbulence Increases Resistance: Turbulent flow wastes energy creating chaotic motion instead of forward movement. Blood particles collide with each other and with plaque, losing momentum. This means the heart must work harder to push blood through, even if the vessel diameter hasn't changed much.

Carlos' Situation: His early atherosclerotic plaque doesn't significantly narrow his brachial artery, but it creates a rough surface. During exercise when blood flows faster, the turbulence gets MUCH worse, dramatically increasing resistance and contributing to his elevated blood pressure.