Initiation of exercise
- As you exercise, the sensory receptors in your muscles, joints, and cardiovascular system detect the increase in activity and metabolic demand. With this, the brain's motor cortex starts the exercise and signals the brainstem's medullary respiratory centers to activate the respiratory muscles.
Moderate Exercise
- The sympathetic nervous system stimulates the respiratory muscles to contract rapidly during moderate exercise, which results in more carbon dioxide being released. The peripheral chemoreceptors (carotid and aortic bodies), detect this change which send signals to the brainstem to increase the respiratory rate.
Abrupt ascent into high altitudes
- The atmospheric pressure decreases as you go to higher altitudes, which leads to lower oxygen partial pressure and oxygen availability. Peripheral chemoreceptors (carotid bodies and aortic bodies) detects this change which sends signals to the brainstem to increase the respiratory rate and depth.
Paralysis of phrenic nerve
- The diaphragm's strength decreases when the phrenic nerve becomes paralyzed and this leads to the thoracic cavity to not expand as much. This lessens the volume of air in the lungs, and it also lowers the ability to take in sufficient air.
Severe Anemia
- Severe anemia decreases the concentration of hemoglobin (an oxygen-carrying molecule), which causes the chemoreceptors to signal the brainstem (medullary respiratory centers). The medullary respiratory centers respond by increasing the respiratory rate and depth because there is a lack of oxygen-carrying molecules in the body.
Advanced pregnancy
- During pregnancy, especially in it's later stages, the uterus expands, which puts pressure on the diaphragm (hindering its contraction and downward movement), which results in a decrease in its expansion capacity. In addition, hormonal changes in the body can affect the brainstem (respiratory control centers) and its control over respiration, causing pregnant women to exhibit a rapid, shallower breathing pattern.