The respiratory system supplies oxygen to the blood.
Large numbers of alveoli increase the surface area, and the walls of alveoli are thin and occasionally secret gas-dissolving liquids. They are also covered in a network of capillaries. All of this makes gas exchange much easier.
Oxygen is taken through the arteries by red blood cells to all of the organs. Carbon dioxide goes out of the body through the nose and is taken there by the veins.
Pneumonia is an inflamation of the lungs. Common symptoms include cough, chest pain, fever, difficulty breathing, loss of appetite, fatigue, bluish skin, nausea, vomiting, mood swings, joint pains, and muscle aches. Most cases can be treated with just antibiotics. In 2008, pneumonia occurred in about 156 million children.
Pulmonary embolism is the blockage of a major blood vessel in the lung. Common symptoms include shortness of breath, chest pain, rapid heart rate, rapid breathing, sweating, anxiety, coughing up blpod, fainting, heart palpitations, and signs of shock. Pulmonary embolism is treated using medications. There are more than 300,000 new cases of pulmonary embolism annually.