First blood enters into the top right chamber, the right atrium, stop there for a moment then drops down into the bottom right chamber, the right ventricle. When your heart beats the used blood in the bottom right chambers shoots out of the heart and through an artery into you lungs.
indicator - (chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction.
Indicators are substances that change colour when they are added to acidic or alkaline solutions. You can prepare homemade indicators from red cabbage or beetroot juice-these will help you see if a solution is acidic or alkaline. Litmus and universal indicator are two indicators that are commonly used in the laboratory.