Briefly explain the main cause or mechanism of increase in respiratory rate or depth and/or respiratory difficulties in the following cases: (one to two sentences only)
Initiation of exercise
- The dorsal respiratory group (DRG) of the medullary respiratory center in the medulla receives excitatory impulses at the beginning of exercise, which causes respiration to increase suddenly. These modifications involve the limbic system being stimulated by the expectation of the action.
Moderate exercise
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Increase in respiratory rate during moderate exercise is caused by chemical and physical changes in the bloodstream, including [1] a slight decrease in PO2; [2] an increase in PCO2; and [3] an increase in temperature due to more heat released.
Abrupt ascent into high altitudes
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The partial pressure of oxygen decreases at high altitude due to the barometric pressure dropping, resulting in a hypoxic effect. The lack of oxygen is detected by the peripheral chemoreceptors, which cause an increase in respiration.
Paralysis of phrenic nerve
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Since the phrenic nerve is responsible for the contraction of the diaphragm, damage to a phrenic nerve can lead to diaphragm weakness or paralysis. This will then lead to breathing problems.
Severe anemia
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Severe anemia happens when one has a very low level of hemoglobin. As a result, blood's ability to provide organs with oxygen is affected, hence the body has to make up for this in order to maintain the same demands through increasing respiratory rate.
Advanced pregnancy
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To meet the greater oxygen needs of the mother and the growing fetus, respiratory increases. This is due to the developing fetus compressing the diaphragm and decreasing the lung capacity, requiring more breathing to keep the oxygen levels sufficient.
References:
- LoMauro, A., & Aliverti, A. (2015). Respiratory physiology of pregnancy. Breathe, 11(4), 297–301. https://doi.org/10.1183/20734735.008615
- Mandoorah, S., & Mead, T. (2020). Phrenic Nerve Injury. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK482227/
- Services, D. of H. & H. (2022, September 26). Anaemia. Www.betterhealth.vic.gov.au. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaemia#:~:text=A%20decreased%20level%20of%20haemoglobin
- Tortora, G. J., & Derrickson, B. H. (2016). Principles of Anatomy and Physiology. Wiley.
- Vissers, H. (2015). Altitude Training and its Effects on the Human Body. https://minds.wisconsin.edu/bitstream/handle/1793/72215/HaleyVissers.pdf?sequence=1#:~:text=One%20change%20experienced%20in%20the