POST-LECTURE ACTIVITY: RESPIRATORY SYSTEM
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)
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Initiation of exercise - The abrupt increase in breathing at the start of exercise is due to neural changes that send excitatory impulses to the dorsal respiratory group (DRG) of the medullary respiratory center in the medulla. The changes include (1) anticipation of the action that activates the limbic system, (2) sensory impulses from proprioceptors in muscles, tendons, and joints, and (3) motor impulses from the primary motor cortex or also called the precentral gyrus.
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Moderate exercise - The increase is mostly brought on by an increase in breathing depth rather than to increase in breathing rate. This is because of the chemical and physical changes in the bloodstream such as (1) the slightly decreased in PO2 due to increased O2 consumption, (2) an slightly increased in PCO2 from the increased CO2 production by contracting muscle fibers, and (3) an increase in temperature from the release of more heat as more O2 is used.
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Asthma attack - The possible causes of respiratory difficulties is due to airway obstruction including (1) smooth muscle spasms in the walls of smaller bronchi and bronchioles, (2) edema of the mucosa of the airways, (3) increased mucus secretion, and (4) damage to the epithelium of the airway. Where the excessive mucus production that occurs along with the smooth muscle spasm might clog the bronchi and bronchioles that restrict the airflow and worsen the attack.
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Abrupt ascent into high altitudes - When abruptly ascent into high altitudes, the partial pressure of oxygen (PO2) decreases, and oxygen (O2) diffuses into the blood more slowly which creates breathing difficulties. This implies that there is less oxygen available for breathing, which causes our respiratory rate to rise.
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Pneumonia - Alveoli that are inflamed or mucous-filled make it harder to breathe and raise the respiratory rate, which can be the cause of pneumonia infection. This is because when specific bacteria or viruses infiltrate our lungs, they release damaging toxins, stimulating inflammation and immune responses with harmful side effects.
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Paralysis of phrenic nerve - The phrenic nerve originates from C3, C4, and C5 and supplies the diaphragm wherein the paralysis of the said nerve may be due to the pressure from malignant tracheal or esophageal tumors in the mediastinum and complete severing the spinal cord at level C2 causes respiratory arrest and stops breathing since phrenic nerves no longer send nerve impulses to the diaphragm.
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Severe tuberculosis with resulting lung scar tissue - Since elastic fibers in our lungs' tissue are easily stretched and surfactant in alveolar fluid lessens surface tension, our lungs typically have high compliance and can expand without difficulty. As a result, severe tuberculosis with resulting lung scar tissue is caused by decreased compliance that resists expansion and makes pulmonary ventilation difficult.
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Severe anemia - Severe anemia has a low number of red blood cells or decreased amount of hemoglobin in the blood consequently which means people having this condition do not get enough oxygen-rich blood or basically the oxygen levels in their blood decrease that is needed for organs to function and causing them difficulty in breathing.
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Advanced COPD (Chronic Obstructive Pulmonary Disease) - The development of COPD, a condition in which the tissue that exchanges oxygen is injured, is smoking, smog, lung diseases, occupational dust and gas exposure, genetic factors, and airway inflammation. This indicates that as the airflow into and out of the lungs decreases, it becomes more difficult to breathe and eliminate the waste gas carbon dioxide, enabling oxygen to enter body tissues.
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Advanced pregnancy - When a woman is pregnant, her uterus begins to grow, move, and push other organs including the diaphragm and lungs, which causes them to be compressed and causes shallow breathing. Another mechanism is when the progesterone levels are high, it makes women breathe faster, which may result to shortness of breath.
Reference: Tortora, G. J., & Derrickson, B. (2014). Principles of Anatomy and Physiology (14th ed.). Wiley.