What causes the sensation of shortness of breath in respiratory conditions?

The sensation of shortness of breath, or dyspnea, is primarily caused by airway constriction and reduced airflow. In respiratory conditions, this constriction can be due to inflammation, bronchoconstriction, or obstruction of the airways. When the airways are narrowed, the resistance to airflow increases, making it more difficult for air to travel in and out of the lungs. This results in a sensation of not getting enough air, which is interpreted by the brain as shortness of breath.

Additionally, the body's response to hypoxia, or low oxygen levels, can further exacerbate this sensation, as the respiratory center in the brain attempts to compensate by increasing the rate and depth of breathing. However, the primary mechanism leading to the feeling of breathlessness is linked to compromised airway function and decreased airflow, which can occur in various respiratory illnesses such as asthma, chronic obstructive pulmonary disease (COPD), or pneumonia.