Oxygen of course(:and many vital nutirents
The Lungs
To the lungs, to be exhaled.
Pulmonary veins.
The inferior vena cava brings blood back to the heart from the lungs.
Arteries.
The pulmonary artery carries deoxygenated blood from the heart to the lungs.
The heart pumps blood to the lungs to be reoxygenated. Valves in our veins and the muscle contractions of our legs helps bring blood from the lower limbs to the heart.
the pulmonary.
The respiratory system removes carbon dioxide from the blood and brings oxygen into the blood. This process occurs through the lungs, where oxygen from the air is exchanged for carbon dioxide in the blood.
In the human body, air is brought into contact with blood in the lungs. This happens through the process of respiration, where oxygen from the air diffuses into the blood in the capillaries surrounding the alveoli in the lungs, and carbon dioxide from the blood diffuses into the air to be exhaled.
When you inhale, your breath is drawn into your lungs, and is exchanged for Carbon Dioxide. The oxygen is 'traded' for Carbon Dioxide from your blood vessels, which leaves the body when you exhale. In other words, inhaling brings Oxygen to your blood.
Carries oxygenated blood from the lungs to the left atria of the heart. Brings blood from the lungs to the heart.