Briefly 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 - the increase in respiratory rate/depth is mainly due to the increased demand of oxygen in our body as muscles contract. neural changes also send excitatory impulses to the dorsal respiratory group (DRG) of the medullary respiratory center in the medulla.
2. Moderate exercise - respiratory rates and depth continuously increase in moderate exercise as the human body releases more carbon dioxide and consumes more oxygen.
3. Abrupt ascent into high altitudes - atmospheric pressure gets lower as the altitude increases, and one will experience shortness of breath/deep breathing. this increase in respiratory rate is due to the need of compensating for the lungs' inability to expand (due to diaphragm contracting and taking up more space/increases in volume)
4. Paralysis of phrenic nerve - as the phrenic nerve is in charge of controlling the diaphragm, it will be detrimental to one's health for this nerve to be paralyzed. lung function and efficiency will decline, which causes multiple respiratory difficulties.
5. Severe anemia - respiratory rates increase in this situation as low hemoglobin levels means that there is a general lack of oxygen in different parts of our body. hyperventilation will occur to return oxygen levels back to normal.
6. Advanced pregnancy - difficulty breathing is common among pregnant women as the fetus currently growing inside the womb is pushing up against the diaphragm, which explains respiratory difficulty being experienced.