Hemopericardium is when the pericardium around your heart fills up with blood (typically from some sort of trauma). As you can imagine, if that sac fills up with blood it’s going to put pressure on the heart, not allow it to freely contract and relax and kill you (that’s called cardiac tamponade). Here we see an unopened pericardium filled with blood.
Blebs are small air sacs that form from the destruction of lung tissue. They’re actually fairly common in the general population, but when they pop they cause the pleural cavity to fill with air, causing the lung to collapse which is a pneumothorax.
The chest cavity is opened at autopsy to reveal numerous large bullae apparent on the surface of the lungs in a patient dying with emphysema. Bullae are large dilated airspaces that bulge out from beneath the pleura. Emphysema is characterized by a loss of lung parenchyma by destruction of alveoli so that there is permanent dilation of airspaces with loss of elastic recoil.