What physiological response does low oxygen levels trigger in the body?

When oxygen levels in the body drop, a physiological response is initiated to compensate for the reduced availability of oxygen—a condition known as hypoxia. To address the need for more oxygen, the body typically increases both the heart rate and the respiratory rate.

An elevated heart rate serves to pump blood more quickly through the circulatory system, facilitating a greater delivery of oxygen-rich blood to vital organs and tissues. Similarly, an increased respiratory rate enables the body to take in more oxygen from the environment, thus improving the oxygen saturation of the blood. This coordinated response helps to mitigate the effects of low oxygen levels, ensuring that essential functions continue and preventing damage to tissues.

The other choices reflect responses that do not align with the body's typical adaptations to low oxygen levels. For example, a decrease in heart rate and respiratory rate would not support the body's need for enhanced oxygen delivery and is contrary to the physiological responses observed in hypoxia. Similarly, increased appetite and sleepiness do not directly relate to compensatory mechanisms for low oxygen, nor do decreased blood pressure and breathing effort, which would further compromise oxygen delivery.