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 sudden increase in respiratory rate at the initiation of exercise is due to the neural changes that send excitatory impulses to the dorsal respiratory group (DRG) of the medullary respiratory center in the medulla.
2. Moderate exercise
As the muscles work harder in moderate exercise, there is an increase in oxygen consumption, carbon dioxide production, and body temperature, which contribute to the increase in breathing or respiratory rate and depth to cater to the needs of the body.
3. Asthma attack
Respiratory difficulties in asthma attacks are caused by airway obstruction, which may be due to smooth muscle spasms in the walls of smaller bronchi and bronchioles, edema of the mucosa of the airways, increased mucus secretion, and/or damage to the epithelium of the airway.
4. Abrupt ascent into high altitudes
In line with the low atmospheric pressure and oxygen levels in high altitudes, the peripheral chemoreceptors sense the abrupt change, leading to hyperventilation, or the increase in breathing and respiratory rate.
5. Pneumonia
As certain microbes enter the lungs and release damaging toxins, the alveoli and bronchial mucous membranes are affected. The inflammation and edema cause the alveoli to fill with fluid, which then interferes with ventilation and gas exchange.
6. Paralysis of phrenic nerve
With the phrenic nerve innervating the diaphragm, its paralysis also paralyzes the diaphragm—causing respiratory difficulties in patients. The contraction and relaxation of the diaphragm is its vital role, and the paralysis may cause shortness of breath and sleeping problems.
7. Severe tuberculosis with resulting lung scar tissue
Mycobacterium tuberculosis bacteria multiply and cause inflammation in the lungs and pleura. Herewith, as the tuberculosis advances and fibrosis occur, respiratory difficulties are caused by the difficulty in the transfer of oxygen from the lungs into the bloodstream due to the thickened lung tissue.
8. Severe anemia
Deficiency of hemoglobin, the component of the blood that carries oxygen, in the blood and the body is the main cause of the increased respiratory rate or tachypnea in individuals with severe anemia. The respiratory rate increases to accommodate the body's need for normal oxygen levels.
9. Advanced COPD (chronic obstructive pulmonary disease)
Chronic obstructive pulmonary disease (COPD) is characterized by chronic and recurrent obstruction of airflow. The resulting airway resistance contributes to the respiratory difficulties experienced by people with advanced COPD, as the body needs to get sufficient oxygen.
10. Advanced pregnancy
As the fetus grows and expands in the uterus, it affects its neighboring organs like the diaphragm and lungs. Hence, advanced pregnancy often causes shortness of breath and exhaustion, even in the simple day-to-day activities, which then requires pregnant women to breathe faster and inhale more oxygen.
References
Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.