N3 Anatomy and Physiology AY 2023-2024

1. Initiation of exercise

• When muscles contract during exercise, they consume large amounts of oxygen and produce large amounts of carbon dioxide. With this, the body needs more oxygen and due to this supply of oxygen, the person starts breathing rapidly.

2. Moderate exercise 

• As the exercise prolongs, more oxygen is used up and levels of carbon dioxide rise. Breathing rate and the volume of air increases, meaning more gaseous exchange takes place which causes both the lungs (increases the respiration rate) and heart (increases the heart rate) to work harder for the supply.

3. Abrupt ascent into high altitudes 

• At altitude, the blood's lower oxygen content causes breathing instability, alternating between periods of deep and fast breathing with central apnea. The primary lung response to acute altitude exposure is hyperventilation, which works in conjunction with an increased heart rate to ensure that the tissues receive an appropriate amount of oxygen.

4 Paralysis of phrenic nerve

• The diaphragm may elevate and become paralyzed when the phrenic nerve is damaged. Since the diaphragm helps with respiration, paralysis may result in breathing problems since the lungs cannot take in and expel air from the outside, since the diaphragm is affected.

5. Severe anemia

• Anemia causes the blood's ability to carry oxygen to decline. The body compensates the drop of oxygen levels by speeding up breathing and heart rate.

10. Advanced pregnancy

• Ventilatory changes in respiratory function are primarily caused by physiological changes in hormone (progesterone) rhythms where a 20% increased consumption of oxygen and 40-50% increase in minute ventilation can be observed. The diaphragm and chest work together in increasing the amount of air breathed in and out.

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