Circulatory System

Heart · blood · vessels

How does the circulatory System work?

A closed loop of vessels — about 100,000 km if laid end to end — with the heart pumping blood through it roughly 100,000 times a day.

Two loops

The right side of the heart pumps blood to the lungs to pick up oxygen; the left side pumps it to the rest of the body.

Delivery

Blood carries oxygen, absorbed nutrients, hormones and immune cells, and carries waste to the lungs, liver and kidneys.

Evidence & sources

• Blood vessels carry oxygen and nutrients to tissues and carry carbon dioxide and wastes away. Evidence: established. Known: Basic physiology. Unknown: — Source: NIH National Heart, Lung, and Blood Institute, How the Heart Works (Current revision).

Connected topics

• Iron
• Potassium
• Sodium
• Omega-3 Fats
• Saturated Fat
• Aerobic Activity

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.