N3 Anatomy and Physiology AY 2023-2024

1. Initiation of exercise

• The medullary rhythmicity is stimulated by proprioceptors  which are responsible for monitoring the movement of joints and muscles. These proprioceptors send nerve impulses to stimulate the DRG of the medulla, increasing the rate and depth of breathing even before exercise. 

2. Moderate exercise

• During exercise, the partial pressures of O2 in the blood of the pulmonary arteries and tissues decrease as more oxygen is used for ATP production. Because of this, diffusion occurs at a faster rate and the body recognizes the greater demand for inhalation and exhalation. 

3. Abrupt ascent into high altitudes

• At high altitudes, our peripheral chemoreceptors is stimulated by the lack of oxygen content. Hence the main response would be hyperventilation with the aim of increasing oxygen content and decreasing carbon dioxide content in the body. 

4. Paralysis of phrenic nerve

• The phrenic nerve is responsible for motor function of the diaphragm, therefore one of the main keyplayers for inhalation and exhalation. An impaired phrenic nerve would result in a paralyzed diaphragm and decreased rate/depth of breathing. 

5. Severe anemia

•  Anemia is caused by the deficient amount of healthy RBCs or hemoglobin to carry oxygen around, hence the chemoreceptors stimulate the medulla oblongata. The response would be hyperventilation or an increased rate and depth of breathing. 

6. Advanced pregnancy

• As the fetus increases the demand of oxygen and progesterone levels increases, the brain responds with increased breathing to satisfy these demands. Breathing is difficult, however, as the enlarging uterus puts pressure of the diaphragm's movements. 

Ben-Joseph, E. P. (2023, January). Why do some women feel short of breath during pregnancy? (for parents) - nemours kidshealth. KidsHealth. https://kidshealth.org/en/parents/breathing.html#:~:text=As%20a%20normal%20part%20of,working%20harder%20to%20get%20air. 

Professional, C. C. medical. (n.d.). Phrenic nerve: Anatomy & Function. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22270-phrenic-nerve