Here's a breakdown of how it works:

* Heart: The heart is a powerful pump that circulates blood throughout the body.

* Blood: Blood is the transportation fluid. It contains red blood cells that carry oxygen, white blood cells that fight infections, and plasma, which carries nutrients and removes waste products.

* Blood Vessels: Blood vessels are the network of tubes that carry blood throughout the body. There are three main types:

* Arteries: Carry oxygenated blood away from the heart to the body.

* Veins: Carry deoxygenated blood back to the heart from the body.

* Capillaries: Tiny blood vessels that connect arteries and veins and allow for the exchange of oxygen, nutrients, and waste products between blood and cells.

How it works:

1. The heart pumps oxygenated blood from the lungs into the arteries.

2. Arteries branch into smaller and smaller vessels, eventually reaching the capillaries.

3. In the capillaries, oxygen and nutrients diffuse from the blood into the surrounding cells.

4. Waste products from the cells diffuse into the capillaries.

5. The deoxygenated blood then travels through veins back to the heart.

6. The heart pumps the deoxygenated blood to the lungs, where it picks up oxygen and releases carbon dioxide.

The circulatory system is vital for delivering oxygen and nutrients to every cell in the body, as well as removing waste products.