The document defines key terms related to the respiratory and circulatory systems, including cells, oxygen, carbon dioxide, heart, blood, arteries, veins, capillaries, and lungs. It explains that the circulatory system transports substances to cells and removes waste, while the respiratory system provides gas exchange between the blood and atmosphere. It also summarizes that cells need oxygen, water, food and waste removal to survive, and the circulatory system delivers these through transport of blood from the heart, through arteries and capillaries to cells, and back to the heart through veins.

1. Living Systems Respiratory & Circulatory Systems Vocabulary and Content