ACTIVITY
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
- There is an abrupt increase in breathing at the onset of exercise due to neural changes that send excitatory impulses to the dorsal respiratory group (DRG) of the medullary respiratory center in the medulla. These changes include anticipation of the activity, which stimulates the limbic system; sensory impulses from proprioceptors in muscles, tendons, and joints; and motor impulses from the primary motor cortex (pre-central gyrus).
2. Moderate Exercise
- There is a more gradual increase in breathing during moderate exercise due to chemical and physical changes in the bloodstream including slightly decreased partial pressure of oxygen due to increased oxygen consumption, slightly decreased partial pressure of carbon dioxide due to increased carbon dioxide production by contracting muscle fibers and increased temperature due to liberation of more heat as more oxygen is utilized.
3. Asthma Attack
- The muscle spasms in the bronchial tubes can close off the airways thus making it difficult to breathe.
4. Abrupt Ascent into High Altitudes
- The signs of high altitude sickness including shortness of breath, headache, fatigue, insomnia, nausea, and dizziness are due to a lower level of oxygen in the blood.
5. Pneumonia
- When certain microbes enter the lungs of susceptible individuals, they release damaging toxins, stimulating inflammation and immune responses that have damaging side effects. The toxins and immune response damage alveoli and bronchial mucous membranes; inflammation and edema cause the alveoli to fill with fluid, which interferes with ventilation and gas exchange.
6. Paralysis of Phrenic Nerve
- The breathing stops when the phrenic nerves are paralyzed because they can no longer send nerve impulses to the diaphragm. Complete severing of the spinal cord above the origin of the phrenic nerves can also cause respiratory arrest.
7. Severe Tuberculosis with Resulting Lung Scar Tissue
- Decreased compliance (low compliance means that they resist expansion of lungs and chest wall) can be the cause of severe tuberculosis with resulting lung tissue.
8. Severe Anemia
- In severe anemia, there is a decrease in the amount of functioning hemoglobin in the blood, resulting in reduced oxygen transport to tissue cells.
9. Advanced COPD (Chronic Obstructive Pulmonary Disease)
- The respiratory difficulties of patients with COPD are because of the increase in airway resistance due to obstruction of collapse of airways.
10. Advanced Pregnancy
- Advanced pregnancy can prevent complete descent of the diaphragm causing respiratory difficulties.