ACTIVITY
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)
1. Initiation of exercise
At the start of exercise, breathing increases abruptly and then gradually. The rapid increase in breathing at the beginning of exercise is caused by neurological alterations that excite the dorsal respiratory group (DRG) of the medullary respiratory center in the medulla (Tortora & Derrickson, 2014).
2. Moderate exercise
The gradual increase that occurs with moderate exercise is mostly brought on by an increase in breathing depth rather than an increase in breathing rate. The more gradual increase in breathing during moderate exercise is due to chemical and physical changes in the bloodstream, which include (1) a slight decrease in PO2, due to increased O2 consumption; (2) an increase in PCO2, due to increased CO2 produced by contracting muscle fibers; and (3) an increase in temperature, due to release of more heat as more O2 is used (Tortora & Derrickson, 2014).
3. Asthma attack
The airways swell and inflame during an asthma attack, also known as an asthma exacerbation. The muscles surrounding the airways constrict, narrowing the bronchial tubes and producing more mucus, which restricts airflow and makes breathing difficult (Mayo Clinic, 2021).
4. Abrupt ascent into high altitudes
According to Henry's Law, the partial pressure of oxygen decreases with an abrupt rise to a high altitude, which lowers its concentration in the blood and creates breathing difficulties. The primary lung response to acute altitude exposure is hyperventilation, which works in conjunction with an increased heart rate to ensure that the tissues receive an appropriate amount of oxygen (Cogo, 2011).
5. Pneumonia
A lung infection known as pneumonia can be brought on by bacteria, viruses, or fungi. Infection results in inflammation of the lungs' air sacs, which leads to a fluid accumulation that makes breathing more difficult (Goldman, 2017).
6. Paralysis of phrenic nerve
The phrenic nerve controls the diaphragm's contraction and expansion, which allows the lungs to take in and release air (Cleveland Clinic, 2022). The diaphragm may potentially become paralyzed if the phrenic nerve is paralyzed, which would make breathing difficult and result in dyspnea or shortness of breath (Kaufman et al., 2022).
7. Severe tuberculosis with resulting lung scar tissue
Severe tuberculosis that scars lung tissue can lead to pulmonary fibrosis, a condition brought on by ongoing lung tissue damage and distinguished by an excessive buildup of extracellular matrix (Ravimohan et al., 2018). It becomes more difficult to breathe as pulmonary fibrosis progresses because the hard, stiff lung tissues don't expand as well as they should (Cleveland Clinic, 2015).
8. Severe anemia
Anemia causes the lungs to overcompensate by trying to take in more oxygen, which makes breathing difficult (Texas Medical Institute, 2020). Individuals with moderate to severe anemia have symptoms of hyperventilation and an increased heart rate as a result of their bodies' ongoing efforts to return oxygen levels to normal (Lepage, 2021).
9. Advanced COPD (chronic obstructive pulmonary disease)
In advanced COPD, the tissue that exchanges oxygen is damaged, and the airways in the lungs enlarge and inflame. Less oxygen enters body tissues as the airflow into and out of the lungs declines, making it more difficult to breathe and expel the waste gas carbon dioxide (American Lung Association, 2022).
10. Advanced pregnancy
Around the 31st to 34th week of pregnancy, the enlarging uterus starts shifting and pushing on other organs of the body, including the diaphragm, the flat muscle that moves up and down when you breathe. These modifications could limit the lungs' ability to fully expand, which would result in shortness of breath (March of Dimes, 2020).
References:
American Lung Association. (2022). Learn About COPD. Lung.org; https://www.lung.org/lung-health-diseases/lung-disease-lookup/copd/learn-about-copd
Cleveland Clinic. (2015). Pulmonary Fibrosis: What is It, Causes, Symptoms, Testing & Treatment. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/10959-pulmonary-fibrosis
Cleveland Clinic. (2022, January 9). Phrenic Nerve: Anatomy & Function. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22270-phrenic-nerve
Cogo, A. (2011). The lung at high altitude. Multidisciplinary Respiratory Medicine, 6(1), 14. https://doi.org/10.1186/2049-6958-6-1-14
Goldman, R. (2017, June 23). The Effects of Pneumonia on the Body. Healthline; Healthline Media. https://www.healthline.com/health/pneumonia/effects-on-body
Kaufman, M. R., Bauer, T. L., & Brown, D. P. (2022). Surgical treatment of phrenic nerve injury (E. Vallières & K. A. Collins, Eds.). Www.uptodate.com; UpToDate. https://www.uptodate.com/contents/surgical-treatment-of-phrenic-nerve-injury
Lepage, R. (2021, November 10). Anemia: The disease that makes you feel like you’re running a never-ending marathon. Biron.com; Nom. https://www.biron.com/en/education-center/specialist-advice/anemia-breathing/#22-90122
March of Dimes. (2020). Shortness of breath. Marchofdimes.org. https://www.marchofdimes.org/complications/shortness-of-breath.aspx
Mayo Clinic. (2021, October 1). Asthma attack - Symptoms and causes. Mayo Clinic; https://www.mayoclinic.org/diseases-conditions/asthma-attack/symptoms-causes/syc-20354268#:~:text=Overview,wheeze%20and%20have%20trouble%20breathing.
Ravimohan, S., Kornfeld, H., Weissman, D., & Bisson, G. P. (2018). Tuberculosis and lung damage: from epidemiology to pathophysiology. European Respiratory Review, 27(147), 170077. https://doi.org/10.1183/16000617.0077-2017
Texas Medical Institute. (2020, July 24). 10 Symptoms of Anemia You Shouldn’t Ignore | Texas Medical Institute. Texas Medical Institute. https://www.texasmedicalinstitute.com/10-symptoms-of-anemia-you-shouldnt-ignore/#:~:text=With%20anemia%2C%20the%20lungs%20overcompensate,oxygen%20from%20reaching%20the%20brain.
Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.