1. Initiation of exercise
The dorsal respiratory group (DRG) receives sensory impulses from proprioceptors in the muscles, tendons, and joints. Upon the start of an exercise, pulmonary ventilation increases depending on the intensity and metabolic needs of the body.
2. Moderate exercise
During moderate exercise, the main function of the respiratory system is to supply sufficient oxygen and increase blood flow to the contracting muscles. Both ventilation and tidal volume are increased to sustain the delivery of oxygen, providing energy as the physical activity continues.
3. Abrupt ascent into high altitudes
As air pressure decreases at higher altitudes, oxygen received by the alveoli decreases, leading to hypoxia. The body goes into hyperventilation as a response, increasing the production of 2,3-biphosphoglyceric acid to lower the affinity of hemoglobin for O2 and transport oxygen to oxygen-deprived areas.
4. Paralysis of phrenic nerve
The phrenic nerve contains motor fibers, innervating the diaphragm and controlling its ability to expand and relax. When the phrenic nerve is paralyzed, the damage affects the diaphragm’s ability to exchange air, leading to some conditions such as shortness of breath, recurrent pneumonia, and insomnia.
5. Severe anemia
Having severe anemia signifies an inadequate amount of red blood cells, specifically hemoglobin, to transport oxygen throughout the body. Due to this condition, the body compensates by increasing respiratory rate, which, in turn, causes fatigue and shortness of breath.
10. Advanced pregnancy
The hormonal influences during advanced pregnancy cause anatomical changes to the respiratory system, such as expansion of the rib cage, reduced lung capacity, and upward movement of the diaphragm by 4cm. Additionally, pulmonary and airway resistances are reduced due to hormonally induced relaxation of the tracheobronchial tree smooth muscles (LoMauro & Aliverti, 2015).
References
Anemia - Symptoms and causes - Mayo Clinic. (2023, May 11). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/anemia/symptoms-causes/syc-20351360
Cleveland Clinic. (n.d.). Phrenic nerve. https://my.clevelandclinic.org/health/body/22270-phrenic-nerve
Department of Health & Human Services. (n.d.). Anaemia. Better Health Channel. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaemia#
James, A. (2023, July 17). Responses of the Respiratory System to Stress. TeachMePhysiology. https://teachmephysiology.com/respiratory-system/regulation/responses-respiratory-system-stress/
LoMauro, A., & Aliverti, A. (2015). Respiratory physiology of pregnancy. Breathe, 11(4), 297–301. https://doi.org/10.1183/20734735.008615
Osmosis - Pulmonary changes at high altitude and altitude sickness | Osmosis. (n.d.). Osmosis. https://www.osmosis.org/learn/Pulmonary_changes_at_high_altitude_and_altitude_sickness#
Phrenic nerve. (n.d.). Physiopedia. https://www.physio-pedia.com/Phrenic_Nerve
Respiratory Responses to Exercise. (n.d.). PT Direct. https://www.ptdirect.com/training-design/anatomy-and-physiology/acute-respiratory-responses
Stanford Medicine Children’s Health. (n.d.). The Lungs in Pregnancy. Standford Medicine. https://www.stanfordchildrens.org/en/topic/default?id=the-lungs-in-pregnancy-90-P02468
Tortora, G. J., & Derrickson, B. (2017). Principles of Anatomy and Physiology (15th ed.). John Wiley & Sons, Inc.