1.4 Chemical Determination. Proteins are complex, organic compounds composed of many amino acids linked together through peptide bonds and cross-linked between chains by sulfhydryl bonds, hydrogen bonds and van der Waals forces.
What causes pleurisy? In young, healthy people, an infection of the lower respiratory system by a virus or bacteria may cause pleurisy. Pleurisy usually lasts a few days to 2 weeks. In very rare cases, the virus or bacteria may spread and cause pleurisy in others. Other causes of pleurisy include air leaking into the pleural cavity from a hole in a lung (pneumothorax), injury to the chest (such as a broken rib), tuberculosis or other infections, or a tumor in the pleura.
Pleurisy occurs when the pleura becomes irritated and inflamed. As a result, the two layers of the pleural membrane rub against each other like two pieces of sandpaper, producing pain when you inhale and exhale. The pleuritic pain lessens or stops when you hold your breath. Causes of pleurisy include: A viral infection, such as the flu (influenza)