Briefly explain the main cause or mechanism of the increase in respiratory rate or depth and/or respiratory difficulties in the following cases: (one to two sentences only)
1. Initiation of exercise: The main cause of the increase in the respiratory rate is the neural changes that send excitatory impulses to the dorsal respiratory group of the medullary respiratory center in the medulla.
2. Moderate exercise: The increase in breathing or respiratory depth during moderate exercise is due to increased oxygen consumption, increased carbon dioxide production, and an increase in body temperature.
3. Asthma attack: The respiratory difficulties experienced by people having asthma attacks are due to the muscle spams in the walls of bronchi and bronchioles, excessive secretion of mucous, and damage to the epithelium of the airway; due to these three causes, people having asthma attacks have a hard time breathing due to trapped air inside the lungs.
4. Abrupt ascent into high altitudes: As the atmospheric pressure is low in high altitudes, the change in oxygen levels (or the lack of oxygen, rather) is sensed by chemoreceptors in the body, which causes hyperventilation, an increase in breathing rate.
5. Pneumonia: The increase in respiratory rate and the respiratory difficulty experienced by people with pneumonia are due to inflammation and edema causing the alveoli to fill with fluid; this interferes with ventilation as it makes it harder for the patients to take breaths.
6. Paralysis of phrenic nerve: The main cause of the respiratory difficulty of patients experiencing paralysis of the phrenic nerve is the paralyzed diaphragm; as the phrenic nerve plays a key role in respiration due to causing the diaphragm to contract and relax, paralysis of the phrenic nerve may cause shortness of breath and sleeping problems.
7. Severe tuberculosis with resulting lung scar tissue: Severe tuberculosis, caused by bacteria, often induces inflammation in the lungs and pleura; with that, the main cause of respiratory difficulty in severe tuberculosis with resulting lung scar tissue (fibrosis) is the difficulty experienced by the body in transferring oxygen from the lungs into the bloodstream due to the thickened lung tissue.
8. Severe anemia: Increased respiratory rate or tachypnea in people with severe anemia is often caused by the deficiency of hemoglobin in the body; it increases the body’s respiratory rate in order to restore its oxygen levels to normal.
9. Advanced COPD (Chronic Obstructive Pulmonary Disease): The respiratory difficulties experienced by people with advanced COPD (e.g. frequent episodes of tachypnea or increased respiratory rate) are caused by the body’s need to compensate for the lack of sufficient oxygen due to the obstruction of airflow.
10. Advanced pregnancy: Due to the changes in a woman during advanced pregnancy, she is expected to breathe faster; this increase in minute ventilation is caused by the limited lung expansion due to the enlarging uterus.