The circulatory, lymphatic, and respiratory systems work together to transport nutrients, gases, and waste throughout the body. The cardiovascular system uses the heart, blood vessels and blood to carry oxygen and nutrients to cells and remove waste. Blood contains plasma, red blood cells, white blood cells and platelets. The lymphatic system returns fluids leaked from tissues to the bloodstream and fights pathogens using lymph nodes and vessels. The respiratory system takes in oxygen through the nose, pharynx, larynx, trachea, bronchi and lungs where gas exchange occurs in alveoli, then expels carbon dioxide.