16.2 Three Layers, Three Vessels

Time To Read

5–7 minutes

Date Last Modified

Age 45


Hyperlipidemia

1

Premature Vascular Aging 

2

Vascular Findings Rooted in the Vessel Wall 

3

Normal, Well-Controlled Blood Pressure (118/74)

4

Diet-Resistant Hyperlipidemia

5

Established, Advancing Coronary Plaque

6

Statin-Intolerant Hyperlipidemia

7

Inflammation-Driven Premature Vascular Aging

Both of Stina’s vascular clues live in vessel walls — calcium in the wall of a coronary artery, an old calcified clot in the wall of a pelvic vein. To make sense of why one vessel hardens and another harbors a clot, you have to start with the wall itself, which follows the same three-layer blueprint everywhere it appears, scaled up or down to the job each vessel does.

Every blood vessel larger than a capillary is built from three tunics. The innermost is the tunica intima, lined by a single sheet of endothelium — the smooth, active surface that touches the blood and controls clotting, tone, and permeability. Around it is the tunica media, a layer of smooth muscle and elastic tissue that sets vessel diameter. Outermost is the tunica externa, a tough collagenous coat that anchors the vessel. Form follows pressure: arteries carry high-pressure blood and so build a thick, muscular, elastic media; veins run at low pressure with thinner walls and one-way valves to keep blood moving toward the heart; capillaries shrink to a single endothelial layer so that exchange can happen across a wall just one cell thick. The endothelium matters most for Stina’s story — it is the layer that, once injured by inflammation, begins the whole cascade toward plaque.

Stina’s two vascular findings live in these layers: her coronary calcium sits in the wall of an artery, her phlebolith in the wall of a vein, and both trace to the same fault line — the intima. The inner lining is a living sensor, glassy and non-stick when healthy, but sticky and permeable when injured or inflamed, and a sticky intima is where LDL seeps in and plaque begins. Read the three tunics and you can read either of her findings; read the intima and you can see where inflammation first touches a vessel.

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