1. Initiation of exercise
- When exercise is initially started, breathing abruptly increases at first, but then gradually increases after. This is because neural changes send certain excitatory impulses to stimulate thee limbic system, the muscles, tendons, and joins, and the primary motor cortex in anticipation of the start of the activity.
2. Moderate exercise
- When exercise is moderate, breathing gradually increases due to both physical and chemical changes in the bloodstream, including changes in gas pressure of the blood and increased temperature.
3. Asthma attack
- Asthma attacks happen because of a lack of patency in the airways. Though there are structures to maintain patency, the lack of supporting cartilage means that muscle spams can block/narrow the bronchial tubes and make it difficult for a person to breathe.
4. Abrupt ascent into high altitudes
- Sudden ascent into high altitudes can result in high altitude sickness, showing symptoms such as shortness of breath, headaches, dizziness, etc. This happens due to a sudden (no acclimation) lower level of oxygen in the blood--as atmospheric pressure decreases when you go up, partial pressure of O2 decreases, which causes O2 diffusion into blood to go more slowly.
5. Pneumonia
- Pneumonia happens due to infection or inflammation of the alveoli--this inflammation stimulates pus/fluid to fill up the alveoli, making it more difficult for oxygen to enter the bloodstream. This makes it harder for a person to breathe and for their bodily function to work as normal.
6. Paralysis of phrenic nerve
- The phrenic nerve serves as the main motor supply of the diaphragm, a major breathing muscle. If the phrenic nerve were to be paralyzed, the breathing muscles would be unable to contract, causing respiratory paralysis.
7. Severe tuberculosis with resulting lung scar tissue
- Tuberculosis is a bacterial infection that causes severe inflammation of the lungs (by the bacteria and the white blood cells trying to fight it), causing lots of fluid to build up in the lungs and making it difficult to breathe. Severe tuberculosis can causes the formation of cavities in the lungs, which may later form scar lung tissue (this causes decreased lung compliance, meaning difficulty for the lungs to expand).
8. Severe anemia
- Anemia happens due to a lack of hemoglobin in the blood, causing less O2 to be transported to cells. With severe anemia, both heart rates and breathing rates rapidly increase constantly due to a severe lack of oxygen being transported throughout the body, making the person feel extremely tired all the time.
9. advanced COPD (chronic obstructive pulmonary disease)
- COPD causes chronic and recurrent airflow obstruction, meaning constant shortness of breath and difficulty in breathing. Advanced COPD can mean a higher respiratory rate due to the body constantly needing more oxygen, as well as risk for heart/blood issues (heart attacks, high blood pressure, etc.).
10. Advanced pregnancy
- In inhalation, the diaphragm usually needs to descend about 1 cm in order to fully breathe. However, advanced pregnancy can prevent the diaphragm from completely descending due to the uterus pressing on the diaphragm--this means that the pregnant woman may find herself taking more shallow breaths than usual and having shortness of breath on occasion.
References
Tortora, G. J., & Derrickson, B. (2012). Principles of Anatomy and Physiology (13th ed.). John Wiley & Sons, Inc.