The respiratory and circulatory systems work together to remove carbon dioxide from the body and deliver oxygen throughout the body. 

The respiratory system allows  us to breathe in oxygen through our mouth and nose and moves it into the lungs. Inside the lungs, oxygen enters millions of tiny air sacs called aveoli. From there, the oxygen passes through the thin walls of the aveoli and into the nearby capillaries, where it enters the blood stream.

In the capillaries, oxygen enters red blood cells and binds to hemoglobin, a protein that carries oxygen. The circulatory system then transports the oxygen-rich cells to the left side of the heart to be pumped around the body for cells to create energy. As the cells create energy, they produce carbon dioxide, which is a waste product. 

The carbon dioxide enters the capillaries and is carried in the blood by hemoglobin, back to the heart to be pumped to the lungs. In the lungs the carbon dioxide moves into the aveoli to be blown out of the body the next time you exhale.  

The lymphatic system and the circulatory system work together to maintain the balance of fluid in our body.

The circulatory system starts things off by moving oxygen-rich blood from the heart into body tissues and organs. Then the veins carry blood containing carbon dioxide and other waste products back to the heart. While 90% of the blood gets sent back to the heart, the remaining 10%  is a fluid that leaks into the body's tissues through the capillaries. This fluid is called lymph, it contains things that are too big to get back into the veins. So the lymphatic system takes over.

Tiny vessels called lymphatic capillaries have small holes that allow lymph to pass through. As the lymph gets passed to vessels with more muscular  walls and one-way valves, it goes to the lymph nodes to filter out the bacteria, waste, and other toxins out of the lymph. If the lymph nodes need to, it can signal the body to launch an immune response.  Then it gets delivered to two large lymphatic ducts below the neck where it gets dumped into a larger vein and back into the blood stream.