Similarly, blood group B has only B antigens, blood group AB has both, and blood group O has neither A nor B antigens on the surface of the red blood cells. These four groups are the most important because they indicate which blood type a patient can safely receive in a transfusion.
Hemoptysis (which is pronounced he-MOP-tis-is) is coughing up blood from the respiratory tract. Blood can come from the nose, mouth, throat, the airway passages leading to the lungs, or the lungs. The word hemoptysis comes from the Greek haima, meaning blood, and ptysis, which means a spitting. Blood-tinged mucus in a healthy nonsmoker usually indicates a mild infection.
In this article. Coughing up blood (hemoptysis) can be a sign of a serious medical condition. Infections, cancer, and problems in blood vessels or in the lungs themselves can be responsible. Coughing up blood generally requires medical evaluation unless the hemoptysis is due to bronchitis.