G5 The Organs of the Body (On Grade)_02

Respiratory System

The respiratory system works together with your cardiovascular system. The lungs are the main organ in your respiratory system. Your lungs work in two ways. They can inhale, or breathe in, and exhale, or breathe out. When you inhale, your lungs fill with fresh oxygen your body needs. The oxygen that gets carried in your blood comes from your lungs. All the cells of your body need oxygen to work properly. When you exhale, you release carbon dioxide back into the air. Carbon dioxide is a waste product from your cells.

The heart pumps blood through the lungs. There, red blood cells absorb oxygen. Then the blood with fresh oxygen is pumped throughout the body to all the cells, using the system of veins and arteries. When you exercise, your cells need more oxygen, they are working harder. This causes you to breathe faster and your heart to beat harder. Your heart must beat more quickly to get the blood carrying the oxygen to the cells. This is how the respiratory system and the circulatory system work together.