Read the questions in each activity and post your answers in the forum assigned for each activity:
Briefly explain the main cause or mechanism of increase in respiratory rate or depth and/or respiratory difficulties in the following cases: (one to two sentences only)
1. 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. These changes include (1) anticipation of the activity, which stimulates the limbic system; (2) sensory impulses from proprioceptors in muscles, tendons, and joints; and (3) motor impulses from the primary motor cortex.
2. Moderate exercise - The more gradual increase in breathing during moderate exercise is due to chemical and physical changes in the bloodstream, including (1) slightly decreased PO2 ,due to increased O2 consumption; (2) slightly increased PCO2 , due to increased CO2 production by contracting muscle fibers; and (3) increased temperature, due to liberation of more heat as more O2 is utilized.
3. Abrupt ascent into high altitudes - The primary reason for an elevated respiratory rate and respiratory challenges upon sudden ascent to high altitudes is hypoxia, characterized by a shortage of oxygen. In elevated regions, the oxygen concentration in the atmosphere decreases, resulting in a decreased supply of oxygen to bodily tissues, including the brain and muscles.
4. Paralysis of phrenic nerve - Phrenic nerve paralysis may affect the diaphragm (unilateral or bilateral); a paralyzed diaphragm affects our lungs' ability to exchange air, which may cause an increase in respiratory rate and respiratory difficulties.
5. Severe anemia - Anemia results in a reduced number of red blood cells; hemoglobin is the protein in red blood cells that binds to oxygen, allowing it to be transported throughout the body. With less hemoglobin and fewer red blood cells, the ability to carry and deliver oxygen to tissues is reduced, which may cause our body to work harder, such as increasing breathing rate or heart rate.
6. Advanced pregnancy - Heightened progesterone levels in pregnancy activate the brain's respiratory center, intensifying the urge to breathe. Although this is crucial for ensuring sufficient oxygen supply to the developing fetus, it may result in an elevated respiratory rate and a sense of breathing discomfort for the expectant mother.
References:
LoMauro, A., & Aliverti, A. (2015). Respiratory physiology of pregnancy: Physiology masterclass. Breathe, 11(4), 297-301. https://doi.org/10.1183/20734735.008615
Tortora, G. J., & Derrickson, B. H. (2017). Principles of Anatomy and Physiology. (15th Ed.). John Wiley & Sons Inc.
Peacock, A. J. (1998). ABC of oxygen: Oxygen at high altitude. BMJ : British Medical Journal, 317(7165), 1063-1066. https://doi.org/10.1136/bmj.317.7165.1063
Cleveland Clinic. (2022, January 9). Phrenic Nerve: Anatomy & Function. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22270-phrenic-nerve
Department of Health & Human Services. (n.d.). Anaemia. Better Health Channel. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaemia