N3 Anatomy and Physiology AY 2023-2024

Explain the main cause or mechanism of increase in respiratory rate or depth and/or respiratory difficulties in the following cases:

1. Initiation of exercise
   • During exercise, the body prompts a need for heightened oxygen. This is to ensure that there is increased oxygen intake and carbon dioxide elimination.
2. Moderate exercise
   • During moderate activities, the bronchioles expand enhancing airflow to and from the alveoli. This expansion improves gas exchange, facilitating a higher rate of oxygen absorption.
3. Abrupt ascent into high altitudes
   • Rapidly ascending to high altitudes triggers increased production of red blood cells, enhancing the blood's oxygen-carrying capability for acclimatization. However, sudden exposure to high altitudes can induce acute altitude sickness in certain individuals, as the body adjusts to the new environment.
4. Paralysis of phrenic nerve
   • When the phrenic nerve fails to function correctly, it restricts the movement of the diaphragm, resulting in breathing difficulties and limited lung expansion. Consequently, air exchange is compromised as the affected side of the diaphragm moves upward during inhalation.
5. Severe anemia
   • Severe anemia reduces the blood's ability to carry oxygen, triggering compensatory responses as well as peripheral vasoconstriction. Similar to the previous cases, this can lead to shortness of breath and weakness.
6. Advanced pregnancy
   • As pregnancy progresses, changes in posture due to the increased weight of the growing fetus can impact breathing, especially while lying down. Hormonal fluctuations, compression of organs, and anemia collectively contribute to the common sensation of breathlessness experienced during this phase of pregnancy.

References

Tortora, G., & Derrickson B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.