1. Initiation of exercise
There is an increase in breathing at the start of the exercise because of the excitatory impulses sent to the dorsal respiratory group of the medullary respiratory center in the medulla oblongata.
2. Moderate exercise
During moderate exercise, the respiratory rate increases because of chemical and physical changes in the bloodstream: slightly decreased oxygen partial pressure due to the need for more oxygen, slightly increased carbon dioxide partial pressure caused by muscle contraction, and increased temperature.
3. Asthma attack
Asthma is caused by chronic airway inflammation, hypersensitivity, and obstruction.
4. Abrupt ascent into high altitudes
The change from high atmospheric pressure (low altitude) to low atmospheric pressure (high altitude) decreases oxygen's partial pressure, resulting in less oxygen inhaled. This event results in a lower amount of oxygen in the blood which in turn causes high-altitude sickness that causes shortness of breath, headache, fatigue, insomnia, nausea, and dizziness.
5. Pneumonia
The main cause of pneumonia is the acute infection or inflammation of the alveoli which is commonly caused by the pneumococcal bacterium Streptococcus pneumoniae. It results in a higher respiratory rate because it causes shortness of breath.
6. Paralysis of phrenic nerve
The paralysis of the phrenic nerve will affect one of the major muscles for inhalation, the diaphragm, because it innervates it.
7. Severe tuberculosis with resulting lung scar tissue
Tuberculosis is caused by the bacterium Myobacterium tuberculosis which affects the lungs and pleurae.
8. Severe anemia
In severe anemia, the blood lacks the normal count of hemoglobin which prevents it from delivering the regular amount of oxygen to the body which increases the respiratory rate because the lungs are forced to bring in more oxygen.
9. advanced COPD (chronic obstructive pulmonary disease)
The most common cause of COPD is regular smoking because it results in chronic obstruction of airflow which affects airway resistance by increasing it.
10. Advanced Pregnancy
Pregnancy can increase the respiratory rate because it prevents the complete contraction of the diaphragm which decreases the maximum amount of air that can be inhaled.