lesson
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Your heart pumps gallons of blood every minute, but it cannot absorb oxygen directly from the blood passing through its chambers.
Instead, the heart muscle relies entirely on its own dedicated network of blood vessels called coronary arteries to deliver oxygen and glucose for aerobic respiration.
📊A cross-section illustration showing the heart surface with branching red coronary arteries wrapping around the muscular myocardium. A callout bubble zooms into a healthy coronary artery in cross-section: wide circular lumen, smooth pink endothelial lining, and steady red blood cells flowing through easily. Labels: 'Aorta', 'Coronary Arteries', 'Lumen (wide)', 'Endothelium (smooth)'.
What happens when these essential supply pipes slowly begin to clog?
Atherosclerosis: The Fatty Build-Up
The inner lining of an artery is the endothelium, a delicate layer of cells that can be damaged by high blood pressure, cigarette toxins, or high blood glucose.
When the endothelium is injured, white blood cells and low-density lipoproteins (LDL, often called 'bad cholesterol') accumulate beneath the lining, forming a fatty deposit called an atheroma.
Over time, calcium salts and fibrous tissue harden the deposit into a rigid plaque, a condition known as atherosclerosis.
📊A 3-step progressive cross-section diagram of an artery: Stage 1: Healthy artery with wide open lumen and smooth inner wall. Stage 2: Fatty streak accumulating beneath the endothelial layer. Stage 3: Hardened, raised atheroma/plaque bulging into the lumen, visibly narrowing the space for blood flow. Animated arrows show red blood cells moving fast in Stage 1 and bunching up/slowing down in Stage 3.
How does a narrowed artery affect the working heart muscle downstream?
Ischaemia and Angina
As the plaque grows, the internal diameter, or lumen, becomes significantly narrower, restricting total blood flow.
This shortage of blood and oxygen supply to a tissue is called ischaemia (or ischemia in American spelling).