Activity
Initiation of exercise - The dorsal respiratory group from the medulla oblongata receives excitatory impulses. Neural changes include anticipation of activity which stimulates the limbic system, sensory impulses from proprioceptors, and motor impulses fom the precentral gyrus leading to increased breathing.
Moderate exercise - Exercise causes PO2 to decrease and PCO2 and temperature to increase, which increases respiratory rate.
Abrupt ascent into high altitudes - Barometic pressure drops leading to less partial pressure of oxygen. Henry's Law states less oxygen is dissolved, leading to hypoxia which will be compensated by an increase in respiration.
Paralysis of phrenic nerve - The phrenic nerve provides the primary motor supply to the diaphragm. Paralysis of the phrenic nerve can lead to respiratory difficulties as the diaphragm is responsible for 75% of inhalation.
Severe anemia - Decrease in RBCs mean less efficiency in transporting gases which the body compensates with increase in respiratory rate.
10. Advanced pregnancy - The uterus expands against the diaphragm, which decreases lung capacity which can be compensated with increased respiratory rate.
References:
Mandoorah, S., & Mead, T. (2023, August 8). Phrenic Nerve Injury. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK482227/
Naître et grandir. (2019, August). Shortness of breath during pregnancy. https://naitreetgrandir.com/en/pregnancy/first-trimester/shortness-breath-during-pregnancy/
Tortora, G. J., & Derrickson, B. H. (2016). Principles of Anatomy and Physiology. Wiley.