1. Initiation of exercise
Because muscle contraction happens during exercise, more oxygen is needed which in turn produce more carbon dioxide. Thus, respiratory depth increases in order to get more oxygen inside the lungs and produce more carbon dioxide outside.
2. Moderate exercise
Since more oxygen is needed during exercise, increase in respiratory rate is facilitated by the expansion of bronchioles. This allows more oxygen to be obtained.
3. Abrupt ascent into high altitudes
The abrupt ascent into high altitudes is sensed by the peripheral chemoreceptors, causing an increase in respiratory rate; this may cause hyperventilation.
4. Paralysis of phrenic nerve
The paralysis of phrenic nerve can cause paralysis of diaphragm, which is an important organ in respiration. It results to difficulty in breathing because the lung expansion is limited, therefore increasing the respiratory rate.
5. Severe anemia
Anemia is a condition characterized by a low supply of blood cells which are responsible in carrying oxygen from the lungs to the different parts of the body. As compensation, the respiratory rate is increased to obtain more oxygen.
6. Advanced pregnancy
In advance pregnancy, the abdominal organs are pushed up to the diaphragm by the baby, causing an increase in respiratory rate to compensate for the limited lung expansion. Moreover, hormonal changes can influence respiratory rate and lung resistance.
References:
Badireddy, M. & Baradhi, K.M. (2023). Chronic Anemia. StatsPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK534803/#:~:text=Anemia%20results%20in%20a%20decreased,heart%20rate%20and%20respiratory%20rate.
Finlay, J. (February 20, 2020). Breathing Changes during Pregnancy. Julia Finlay Osteopath. Retrieved from https://www.juliafinlayosteopath.co.uk/blog/breathing-changes-during-pregnancy
Libretexts Medicine (2023, January 17). 21.11b: Adjustments at high altitude. Medicine LibreTexts. Retrieved from https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiology_(Boundless)/21%3A_Respiratory_System/21.11%3A_Respiratory_Adjustments/21.11B%3A_Adjustments_at_High_Altitude#:~:text=for%20too%20long.-,Short%2DTerm%20Adjustments,in%20breathing%20rate%20(%20hyperventilation%20).
LoMauro, A., & Aliverti, A. (2015). Respiratory physiology of pregnancy: Physiology masterclass. Breathe (Sheffield, England), 11(4), 297–301. https://doi.org/10.1183/20734735.008615
Patel, P.R. & Bechmann, S. (2023). Elevated Hemidiaphragm. StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK559255