4. Acute bronchitis is inflammation of bronchial mucosa caused by pathogen infection such as virus or bacteria. It is a common and frequently-occurring disease in infants, often secondary to upper respiratory tract infection, and the early manifestations of pneumonia are often audible and wheezing. Persistent local chest signs suggest the occurrence of bronchopneumonia. The main function of antidiuretic hormone is to improve the permeability of distal convoluted tubules and collecting ducts to water and promote the absorption of water, which is the key regulating hormone for urine concentration and dilution.