A. 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
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During the initiation of exercise, increased respiratory rate and depth occur due to the body's need for more oxygen to support heightened physical activity. As exercise begins, the muscles demand extra oxygen to produce energy, leading to a reflexive increase in breathing to meet this demand.
2. Moderate exercise
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In the case of moderate exercise, the respiratory rate and depth rise to supply the body with additional oxygen required to sustain the ongoing physical activity. As exercise continues, the muscles continue to consume oxygen, and the respiratory system adjusts to maintain an appropriate oxygen supply for the body's needs during moderate exertion.
3. Abrupt ascent into high altitudes
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The primary mechanism behind an increase in respiratory rate and depth when ascending to high altitudes is the reduced oxygen levels (hypoxia) due to lower oxygen pressure. To compensate for this, the body responds with hyperventilation, characterized by an increase in both tidal volume and breathing rate, to ensure sufficient oxygen supply to the body's tissues in the oxygen-scarce high-altitude environment, aiding in acclimatization but potentially leading to high-altitude illnesses when not properly adapted.
4. Paralysis of phrenic nerve
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Paralysis of the phrenic nerve impairs breathing by affecting the diaphragm, causing breathlessness during physical activity and when lying down when one nerve is involved, and severe breathing difficulties when both nerves are affected, potentially requiring interventions like diaphragmatic pacing or microsurgery to restore function.
5. Severe anemia
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Severe anemia leads to an increase in respiratory rate and depth as a response to the blood's reduced oxygen-carrying capacity caused by low hemoglobin levels. This compensatory mechanism involves the body working harder, including raising both breathing and heart rates, resulting in symptoms like breathlessness and fatigue due to inadequate oxygen delivery to the body's tissues.
10. Advanced pregnancy
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In advanced pregnancy, the main cause of an increase in respiratory rate and potential respiratory difficulties is the enlarged uterus placing pressure on the diaphragm. This pressure makes it harder for the diaphragm to contract efficiently, increasing the energy needed for breathing and reducing the available oxygen for aerobic exercise, which can lead to a decreased ability to maintain the same level of intensity or work throughout pregnancy.
References:
Cogo A. (2011). The lung at high altitude. Multidisciplinary respiratory medicine, 6(1), 14–15. https://doi.org/10.1186/2049-6958-6-1-14
Department of Health & Human Services. (n.d.). Anaemia. Better Health Channel. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaemia
Grünebaum, A. (2018, August 21). Respiratory body changes during pregnancy. babyMed.com. https://www.babymed.com/respiratory-body-changes-during-pregnancy
Mehta, P. (2022, October 11). Phrenic nerve: What to know. WebMD. https://www.webmd.com/lung/phrenic-nerve-what-to-know
Tortora, G., & Derrickson, B. (2012). Principles of ANATOMY & PHYSIOLOGY (13th ed.). John Wiley & Sons, Inc.