New York State Emergency Medical Technician (EMT) Practice Exam

How does an elevated level of carbon dioxide in the blood affect respiration?

1. It decreases the respiratory rate

2. It has no effect on respiration

3. It stimulates an increase in respiratory rate

4. It causes shallow breathing

The correct answer is: It stimulates an increase in respiratory rate

An elevated level of carbon dioxide in the blood, a condition known as hypercapnia, leads to an increase in the respiratory rate. This is because the body regulates breathing primarily based on the levels of carbon dioxide rather than oxygen. When carbon dioxide levels rise, it creates a condition of acidosis in the blood, which is detected by chemoreceptors located in the medulla oblongata and carotid bodies. These receptors trigger the respiratory control centers to increase the rate and depth of breathing, allowing the excess carbon dioxide to be expelled from the body more effectively. This physiological response is crucial for maintaining proper acid-base balance and ensuring that sufficient oxygen is delivered to the tissues. In summary, an increase in carbon dioxide levels stimulates the body to breathe more rapidly in order to regulate blood gas levels and maintain homeostasis.