In the majority of cases, incontinence is caused by a weakening of the pelvic floor muscles that keep the urethra closed. Whenever they lose their elasticity, everyday activities such as laughing, coughing, lifting and running can cause a urine leak.
The respiratory system consists of a group of ducts that are capable of filtering air from the environment before entering the pulmonary system.
The primary purpose of the respiratory system is the equilibration of the partial pressures of the respiratory gases in the alveolar air with those in the pulmonary capillary blood (Fig. 11). This process occurs by simple diffusion, across a very thin membrane (known as the bloodâair barrier), which forms the walls of the pulmonary alveoli (Fig. 10).