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How does the circulatory system deliver oxygen and nutrients to cells?
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human body
Vintage anatomy charts of the human body showing the skeletal and muscle systems.
The circulatory system delivers oxygen and nutrients to cells through a highly efficient transport network powered by the heart.12
The process functions as follows:
- Oxygen Transport: Oxygen is picked up in the lungs, where it binds to hemoglobin within red blood cells. These cells are specialized to carry oxygen throughout the body to tissues that require it for metabolism.312
- Nutrient Delivery: Nutrients derived from food are absorbed into the bloodstream via the gastrointestinal tract and transported in the plasma to cells throughout the body.1
- Capillary Exchange: The actual delivery occurs at the level of capillaries, which are tiny blood vessels with thin walls. Through these walls, oxygen, nutrients, and hormones pass from the bloodstream into the surrounding cells. Simultaneously, carbon dioxide and other metabolic waste products move from the tissues into the blood to be transported away for removal.45
This continuous exchange is the primary function of systemic circulation, ensuring that nearly every cell in the body receives the materials necessary for survival and activity.45