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-blood flows in and out with each heartbeat.

-the chambers squeeze and then relax.

-the chambers send blood through the heart and into blood vessels.

-each atrium and ventricle squeezes.

-the valves open when the squeezes happen.

-valves keep blood flowing in the right direction.

-when the left atrium contracts (squeezes) the mitral valve opens.

-when the blood flows into the left ventricle, the valve closes.

-the left ventricle contracts pushing blood to the rest of the body.

-the left ventricle is a strong muscle.

-there are 60,000 miles of blood vessels in the human body.

-the arteries carry blood away from the art (arteries = away)

-the veins carry blood to the heart

-capillaries connect arteries and veins (capillaries = connect.