Answer:
The heart and the blood vessels are a part of the circulatory system. The blood vessels include the arteries, veins and capillaries. The lungs are considered to be the pulmonary part of the circulatory system. The heart is the cardiovascular part of the circulatory system and the vessels are the systemic part of the circulatory system. The main function of the circulatory system is to supply all parts of the body with oxygenated blood and to take away the deoxygenated blood from all parts of the body.
When you doing a titration, you need to use an indicator to confirm whether the reaction is completed. When the indicator has the color change and will not change back in one minute, the reaction is finished and you don't need to add more.